TomoTherapy Incorporated (NASDAQ: TOMO) announced that it will introduce the TomoDirect™ discrete-angle delivery mode1 for the TomoTherapy® Hi·Art® treatment system at two upcoming radiation oncology conferences. This innovative new technology allows Hi·Art system users to quickly plan and deliver advanced TomoTherapySM radiation treatments with a series of linear beam paths, rather than the existing helical path. With TomoDirect, clinicians can choose several discrete angles and the optimal modulation level required for delivery, based on specific patient therapy goals. TomoDirect will be unveiled at the annual meetings of the European Society for Therapeutic Radiology and Oncology (ESTRO) in Gothenburg, Sweden, Sept. 14-18, 2008, and the American Society for Therapeutic Radiology and Oncology (ASTRO) in Boston, Mass., Sept. 21-25, 2008.
"We are excited about TomoDirect because it will greatly increase the overall flexibility and efficiency of the Hi·Art treatment system," said Fred Robertson, CEO of TomoTherapy. "Along with helical TomoTherapy delivery, TomoDirect will enhance our customers' revenue-generating opportunities, and strengthen their ability to deliver the highest quality radiation therapy to the broadest patient population."
TomoDirect was developed as a complement to helical TomoTherapy, with both utilizing the same binary multi-leaf collimator and CT-style gantry technology. The choice of which modality to use for a given case will depend on the nature of the tumor volume and surrounding organs at risk. TomoDirect is expected to provide significant time savings in both the planning and delivery phases for several clinical scenarios, including whole breast irradiation and palliative treatments.
Said TomoDirect research partner Paul Read, M.D., Ph.D., assistant professor of Radiation Oncology, University of Virginia: "TomoDirect will expand the spectrum of external beam radiation therapy patients who can be optimally treated with TomoTherapy's unique image-guided, intensity-modulated radiation therapy (IG-IMRT). Now, we will have an option to deliver dose via two unique and complementary delivery modes, choosing whichever provides the optimal dose distribution. Clearly, breast cancer patients will benefit from TomoDirect, and other disease sites will likely be developed for which there is clinical benefit."
Added research partner Prof. Guy Storme, M.D., Ph.D., director of the Oncologic Center at UZ Brussel, Brussels, Belgium: "Certainly, with the combination of helical and direct deliveries, TomoTherapy should offer significant benefit for a majority of breast cancer treatments. It will provide the ability to choose and apply the right modality for the best treatment. Our research is focused on providing comprehensive usage guidelines as we study and validate this new mode combination."
The TomoDirect delivery mode leverages the Hi·Art treatment system's unique design, componentry and capabilities. According to TomoTherapy co-founder Thomas "Rock" Mackie, Ph.D., Hi·Art system integration facilitates a simple, consistent treatment planning and delivery process across both modes of delivery.
"TomoDirect will use all the power of the platform that makes helical TomoTherapy the gold standard in radiation therapy," said Mackie. "The difference is that we expect treatment planning times will be dramatically reduced due to the much smaller number of beam directions used. Furthermore, for certain geometries, the ability to use only the most beneficial angles will cut delivery times significantly. With TomoDirect, routine cases can now be planned in under 10 minutes. And, importantly, users can deliver from up to 12 discrete angles, with a single turn of the key."
In addition to the added capabilities offered by TomoDirect, the Hi·Art system's treatment modes are being expanded to include a 3D conformal option, thereby meeting the full range of options needed for all clinical cases.
Concluded Robertson: "TomoTherapy has already been embraced for its superior treatment quality, especially for complex cases. The introduction of TomoDirect will fully open the door for the Hi·Art system to have a significant presence in all settings, from large academic centers to single linac centers where high patient throughput is paramount. TomoDirect will effectively increase our access to a larger percentage of the radiation therapy market opportunities."
1 TomoTherapy is planning to make TomoDirect available to radiation clinics in summer 2009. As a product pending FDA 510(k) clearance, TomoDirect is not yet available for sale in the United States.
About TomoTherapy Incorporated
TomoTherapy Incorporated has developed, markets and sells the TomoTherapy® Hi·Art® treatment system, an advanced radiation therapy system for the treatment of a wide variety of cancers. The Hi·Art treatment system combines integrated CT imaging with conformal radiation therapy to deliver sophisticated radiation treatments with speed and precision while reducing radiation exposure to surrounding healthy tissue. The company's stock is traded on the NASDAQ Global Select Market under the symbol TOMO. To learn more about TomoTherapy, please visit TomoTherapy.com.
Forward-Looking Statements
Statements in this release regarding future products, events, expectations and other similar matters, including but not limited to statements using the terms "will", "can", "is expected to", or "should" constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements contained in this press release are subject to risks and uncertainties that could cause actual results to differ materially from those anticipated, including but not limited to factors such as our ability to integrate acquired assets, ability to protect intellectual property, risks of interruption due to events beyond the company's control, and the other risks listed from time to time in TomoTherapy's filings with the U.S. Securities and Exchange Commission, which by this reference are incorporated herein. These forward-looking statements represent TomoTherapy's judgments as of the date of this press release. TomoTherapy assumes no obligation to update or revise the forward-looking statements in this release because of new information, future events or otherwise.
©2008 TomoTherapy Incorporated. All rights reserved. TomoTherapy, TomoDirect, the TomoTherapy logo and Hi·Art are among trademarks, service marks or registered trademarks of TomoTherapy Incorporated.
Monday, August 11, 2008
antibiotic works
Antibiotics, sometimes known as antibacterials, are drugs used to treat infections caused by bacteria. These are tiny organisms, too small to see with the naked eye, that sometimes cause illness in humans. Well-known illnesses caused by bacteria include tuberculosis, salmonella, syphilis and some forms of meningitis. However many types of bacteria do not cause illness and live harmlessly on, and in, the human body.
Our immune systems, with their antibodies and special white blood cells, can usually kill harmful bacteria before they multiply enough to cause symptoms. And even when symptoms do occur, the body can often fight off the infection. But sometimes the body is overwhelmed by a bacterial infection and needs help to get rid of it. This is where antibiotics come in. The very first antibiotic was penicillin and along with a family of related antibiotics (such as ampicillin, amoxicllin and benzylpenicillin) it is still widely used to treat many common infections. Now there are several other different kinds of antibiotics. All of them are only available on prescription.
HOW DO ANTIBIOTICS WORK?
Some antibiotics, such as the penicillins, are 'bactericidal', meaning that they work by killing bacteria. They do this by interfering with the formation of the cell walls or cell contents of the bacteria. Other antibiotics are 'bacteriostatic', meaning that they work by stopping bacteria multiplying.
WHAT ARE ANTIBIOTICS FOR?
Antibiotics are usually used to treat infections caused by bacteria. They do not work against other organisms such as fungi or infectious agents such as viruses . It's important to bear this in mind if you think you have some sort of infection, because many common illnesses, particularly of the upper respiratory tract such as the common cold and sore throats, are usually caused by viruses. Overuse of antibiotics can lead to bacteria becoming resistant to them so it's important to only take them when necessary. (See this page).
Some antibiotics can be used to treat a wide range of infections and are known as 'broad-spectrum' antibiotics. Others are only effective against a few types of bacteria and are called 'narrow-spectrum' antibiotics. Some antibiotics work against aerobic bacteria, that is organisms that need oxygen to live, while others work against anaerobic bacteria, organisms that don't need oxygen. Sometimes antibiotics are given to prevent an infection occurring, for example, before certain operations. This is known as prophylactic use of antibiotics and is common before orthopaedic and bowel surgery.
SIDE EFFECTS OF ANTIBIOTICS
The most common side effects with antibiotic drugs are diarrhoea, feeling sick and being sick. Fungal infections of the mouth, digestive tract and vagina can also occur with antibiotics because they destroy the protective 'good' bacteria in the body (which help prevent overgrowth of any one organism), as well as the 'bad' ones, responsible for the infection being treated.
Rare, but more serious side effects, include the formation of kidney stones with the sulphonamides, abnormal blood clotting with some of the cephalosporins, increased sensitivity to the sun with the tetracyclines, blood disorders with trimethoprim, and deafness with erythromycin and the aminoglycosides.
Sometimes, particularly in older people, antibiotic treatment can cause a type of colitis (inflamed bowel) leading to severe diarrhoea. Penicillins, cephalosporins and erythromycin can all cause this problem but it is most common with clindamycin, an antibiotic usually reserved for serious infections. If you develop diarrhoea while taking an antibiotic, immediately contact your doctor.
Some people are allergic to antibiotics, particularly penicillins, and can develop Side effects such as a rash, swelling of the face and tongue, and difficulty breathing when they take them. Always tell your doctor or pharmacist if you have had an allergic reaction to an antibiotic; sometimes the reaction can be serious or even fatal. This is called an anaphylactic reaction.
USE ANTIBIOTICS WITH CARE IF ...
You should use an antibiotic with care if you have reduced liver or kidney function. You should avoid using any antibiotic to which you have previously had an allergic reaction.
TELL YOUR DOCTOR OR PHARMACIST IF YOU ARE PREGNANT OR BREASTFEEDING BEFORE TAKING ANY ANTIBIOTIC.
INTERACTIONS WITH OTHER MEDICINES
Do not take any other medicines or herbal remedies with an antibiotic, including those you have bought without a prescription, before talking to your doctor or pharmacist.
-- Certain antibiotics (e.g. penicillins, cephalosporins) can reduce the effectiveness of oral contraceptives. If you have diarrhoea or vomiting while taking an antibiotic, the absorption of the pill can be disrupted. In either case, you should take additional contraceptive precautions while you are taking the antibiotic.
-- There are a number of important interactions between antibiotics and other medicines so it's important to tell which your doctor or pharmacist about any other medicines you are taking.
HOW TO USE AN ANTIBIOTIC
Antibiotics are usually taken orally but can also be given by injection, or applied to the affected part of the body such as the skin, eyes or ears. The drugs begin to tackle most infections within a few hours. It is vital to take the whole course of treatment to prevent recurrence of the infection. Sometimes bacteria become 'resistant' to an antibiotic you have been taking, meaning that the drug will no longer work. Resistance tends to occur when the bacterial infection responsible for the symptoms is not completely cured, even if the symptoms have cleared up. Some of the residual bacteria, having been exposed to, but not killed by, the antibiotic are more likely to grow into an infection that can survive that particular antibiotic. This explains why finishing the course of antibiotics, even if you feel better, is important.
Certain antibiotics should not be taken with certain foods and drinks. Some antibiotics are best taken when there is no food in your stomach, usually an hour before meals or two hours after - make sure you follow the instructions on the dispensing label. Do not drink alcohol if you are taking metronidazole. Do not take tetracyclines with dairy products, as these can reduce the absorption of this type of antibiotic.
COMMON ANTIBIOTICS
Our immune systems, with their antibodies and special white blood cells, can usually kill harmful bacteria before they multiply enough to cause symptoms. And even when symptoms do occur, the body can often fight off the infection. But sometimes the body is overwhelmed by a bacterial infection and needs help to get rid of it. This is where antibiotics come in. The very first antibiotic was penicillin and along with a family of related antibiotics (such as ampicillin, amoxicllin and benzylpenicillin) it is still widely used to treat many common infections. Now there are several other different kinds of antibiotics. All of them are only available on prescription.
HOW DO ANTIBIOTICS WORK?
Some antibiotics, such as the penicillins, are 'bactericidal', meaning that they work by killing bacteria. They do this by interfering with the formation of the cell walls or cell contents of the bacteria. Other antibiotics are 'bacteriostatic', meaning that they work by stopping bacteria multiplying.
WHAT ARE ANTIBIOTICS FOR?
Antibiotics are usually used to treat infections caused by bacteria. They do not work against other organisms such as fungi or infectious agents such as viruses . It's important to bear this in mind if you think you have some sort of infection, because many common illnesses, particularly of the upper respiratory tract such as the common cold and sore throats, are usually caused by viruses. Overuse of antibiotics can lead to bacteria becoming resistant to them so it's important to only take them when necessary. (See this page).
Some antibiotics can be used to treat a wide range of infections and are known as 'broad-spectrum' antibiotics. Others are only effective against a few types of bacteria and are called 'narrow-spectrum' antibiotics. Some antibiotics work against aerobic bacteria, that is organisms that need oxygen to live, while others work against anaerobic bacteria, organisms that don't need oxygen. Sometimes antibiotics are given to prevent an infection occurring, for example, before certain operations. This is known as prophylactic use of antibiotics and is common before orthopaedic and bowel surgery.
SIDE EFFECTS OF ANTIBIOTICS
The most common side effects with antibiotic drugs are diarrhoea, feeling sick and being sick. Fungal infections of the mouth, digestive tract and vagina can also occur with antibiotics because they destroy the protective 'good' bacteria in the body (which help prevent overgrowth of any one organism), as well as the 'bad' ones, responsible for the infection being treated.
Rare, but more serious side effects, include the formation of kidney stones with the sulphonamides, abnormal blood clotting with some of the cephalosporins, increased sensitivity to the sun with the tetracyclines, blood disorders with trimethoprim, and deafness with erythromycin and the aminoglycosides.
Sometimes, particularly in older people, antibiotic treatment can cause a type of colitis (inflamed bowel) leading to severe diarrhoea. Penicillins, cephalosporins and erythromycin can all cause this problem but it is most common with clindamycin, an antibiotic usually reserved for serious infections. If you develop diarrhoea while taking an antibiotic, immediately contact your doctor.
Some people are allergic to antibiotics, particularly penicillins, and can develop Side effects such as a rash, swelling of the face and tongue, and difficulty breathing when they take them. Always tell your doctor or pharmacist if you have had an allergic reaction to an antibiotic; sometimes the reaction can be serious or even fatal. This is called an anaphylactic reaction.
USE ANTIBIOTICS WITH CARE IF ...
You should use an antibiotic with care if you have reduced liver or kidney function. You should avoid using any antibiotic to which you have previously had an allergic reaction.
TELL YOUR DOCTOR OR PHARMACIST IF YOU ARE PREGNANT OR BREASTFEEDING BEFORE TAKING ANY ANTIBIOTIC.
INTERACTIONS WITH OTHER MEDICINES
Do not take any other medicines or herbal remedies with an antibiotic, including those you have bought without a prescription, before talking to your doctor or pharmacist.
-- Certain antibiotics (e.g. penicillins, cephalosporins) can reduce the effectiveness of oral contraceptives. If you have diarrhoea or vomiting while taking an antibiotic, the absorption of the pill can be disrupted. In either case, you should take additional contraceptive precautions while you are taking the antibiotic.
-- There are a number of important interactions between antibiotics and other medicines so it's important to tell which your doctor or pharmacist about any other medicines you are taking.
HOW TO USE AN ANTIBIOTIC
Antibiotics are usually taken orally but can also be given by injection, or applied to the affected part of the body such as the skin, eyes or ears. The drugs begin to tackle most infections within a few hours. It is vital to take the whole course of treatment to prevent recurrence of the infection. Sometimes bacteria become 'resistant' to an antibiotic you have been taking, meaning that the drug will no longer work. Resistance tends to occur when the bacterial infection responsible for the symptoms is not completely cured, even if the symptoms have cleared up. Some of the residual bacteria, having been exposed to, but not killed by, the antibiotic are more likely to grow into an infection that can survive that particular antibiotic. This explains why finishing the course of antibiotics, even if you feel better, is important.
Certain antibiotics should not be taken with certain foods and drinks. Some antibiotics are best taken when there is no food in your stomach, usually an hour before meals or two hours after - make sure you follow the instructions on the dispensing label. Do not drink alcohol if you are taking metronidazole. Do not take tetracyclines with dairy products, as these can reduce the absorption of this type of antibiotic.
COMMON ANTIBIOTICS
Friday, July 18, 2008
the doctor
By meeting yearly with your teen, the doctor can keep track of changes in his or her physical, mental, and social development and offer advice against unhealthy behaviors, such as smoking and drinking. The doctor can also help your child understand the importance of choosing a healthy lifestyle that includes good nutrition, proper exercise, and safety measures. The more teens understand about their physical growth and sexual development, the more they will recognize the importance of active involvement in their own health care.
What Happens at the Doctor's Office?
Teens should visit their doctors annually. At least three of these visits should include a complete physical examination: one performed during early adolescence (ages 11 to 14), one during middle adolescence (ages 15 to 17), and one during late adolescence (ages 18 to 21). If your child has a chronic medical condition or if certain clinical signs or symptoms are present, more frequent examinations may be indicated.
Medical care should include screenings for high blood pressure, obesity, and other eating disorders, and, if indicated, hyperlipidemia (an excess of cholesterol and/or other fats in the blood). A tuberculin (PPD) test may be administered if your teen is at risk for tuberculosis.
Your teen's doctor will also check his or her teeth for tooth decay, abnormal tooth development, malocclusion (abnormal bite), dental injuries, and other problems. Your teen should also continue to have regular checkups with her dentist.
Vision and hearing will be checked.
Teens will also be checked for scoliosis (curvature of the spine).
Teens should receive a diphtheria and tetanus booster (Td) 10 years after their last childhood booster (usually at age 4 to 6 years) and every 10 years thereafter. They should have already completed their other immunizations, including varicella (if they have not had chickenpox); measles, mumps, and rubella (MMR); and the hepatitis B series (Hep B). If your teen will be living in an institutional setting, such as a college dormitory, speak with his or her doctor about receiving the meningococcal meningitis vaccine.
As your child goes through puberty, issues of sexual health will be addressed. Your child's doctor will teach your daughter how to perform a monthly breast exam. The doctor may also perform (or refer her to a gynecologist for) a gynecologic exam and a Pap smear to check for cervical cancer. Males will be checked for hernias and testicular cancer and taught to perform a testicular self-examination.
Teens should be asked about behaviors or emotional problems that may indicate depression or the risk of suicide. The doctor should also provide counseling about risky behaviors and other issues, including:
* sexual activities that may result in unintended pregnancy and sexually transmitted diseases (STDs), including HIV
* emotional, physical, and sexual abuse
* use of alcohol and other substances, including anabolic steroids
* use of tobacco products, including cigarettes and smokeless tobacco
* use of alcohol while driving
* use of safety devices, including bicycle helmets, seat belts, and protective sports gear
* how to resolve conflicts without violence, including how to avoid the use of weapons
* learning problems or difficulties at school
* appropriate warm-ups before exercise and importance of regular physical activity
What Should I Do if I Suspect a Medical Problem?
Parents or other caregivers should receive health guidance at least once during early, middle, and late adolescence from their teen's doctor. During these sessions, the doctor will provide information about normal development, including signs and symptoms of illness or emotional distress and methods to monitor and manage potentially harmful behaviors.
If you suspect that your teen has a physical disorder, a psychological problem, or a problem with drugs or alcohol, contact your child's doctor immediately.
Typical Medical Problems
Issues involving puberty and sexual development are typical concerns for this age group. Doctors who establish a policy of confidentiality can serve as a valuable resource for a teen by answering questions and providing guidance during this period of physical and emotional changes. Teens should be reassured that anything they discuss with their doctor will be kept confidential, unless their health or the health of others is endangered by the situation.
Sports injuries are common concerns. Osgood-Schlatter disease, a painful inflammation of the area just below the front of the knee, is particularly common in the early teen years. Knee pain is also a frequent complaint. Your teen's doctor should evaluate any severe or persistent pain of the joints, muscles, or other areas of the body.
What Happens at the Doctor's Office?
Teens should visit their doctors annually. At least three of these visits should include a complete physical examination: one performed during early adolescence (ages 11 to 14), one during middle adolescence (ages 15 to 17), and one during late adolescence (ages 18 to 21). If your child has a chronic medical condition or if certain clinical signs or symptoms are present, more frequent examinations may be indicated.
Medical care should include screenings for high blood pressure, obesity, and other eating disorders, and, if indicated, hyperlipidemia (an excess of cholesterol and/or other fats in the blood). A tuberculin (PPD) test may be administered if your teen is at risk for tuberculosis.
Your teen's doctor will also check his or her teeth for tooth decay, abnormal tooth development, malocclusion (abnormal bite), dental injuries, and other problems. Your teen should also continue to have regular checkups with her dentist.
Vision and hearing will be checked.
Teens will also be checked for scoliosis (curvature of the spine).
Teens should receive a diphtheria and tetanus booster (Td) 10 years after their last childhood booster (usually at age 4 to 6 years) and every 10 years thereafter. They should have already completed their other immunizations, including varicella (if they have not had chickenpox); measles, mumps, and rubella (MMR); and the hepatitis B series (Hep B). If your teen will be living in an institutional setting, such as a college dormitory, speak with his or her doctor about receiving the meningococcal meningitis vaccine.
As your child goes through puberty, issues of sexual health will be addressed. Your child's doctor will teach your daughter how to perform a monthly breast exam. The doctor may also perform (or refer her to a gynecologist for) a gynecologic exam and a Pap smear to check for cervical cancer. Males will be checked for hernias and testicular cancer and taught to perform a testicular self-examination.
Teens should be asked about behaviors or emotional problems that may indicate depression or the risk of suicide. The doctor should also provide counseling about risky behaviors and other issues, including:
* sexual activities that may result in unintended pregnancy and sexually transmitted diseases (STDs), including HIV
* emotional, physical, and sexual abuse
* use of alcohol and other substances, including anabolic steroids
* use of tobacco products, including cigarettes and smokeless tobacco
* use of alcohol while driving
* use of safety devices, including bicycle helmets, seat belts, and protective sports gear
* how to resolve conflicts without violence, including how to avoid the use of weapons
* learning problems or difficulties at school
* appropriate warm-ups before exercise and importance of regular physical activity
What Should I Do if I Suspect a Medical Problem?
Parents or other caregivers should receive health guidance at least once during early, middle, and late adolescence from their teen's doctor. During these sessions, the doctor will provide information about normal development, including signs and symptoms of illness or emotional distress and methods to monitor and manage potentially harmful behaviors.
If you suspect that your teen has a physical disorder, a psychological problem, or a problem with drugs or alcohol, contact your child's doctor immediately.
Typical Medical Problems
Issues involving puberty and sexual development are typical concerns for this age group. Doctors who establish a policy of confidentiality can serve as a valuable resource for a teen by answering questions and providing guidance during this period of physical and emotional changes. Teens should be reassured that anything they discuss with their doctor will be kept confidential, unless their health or the health of others is endangered by the situation.
Sports injuries are common concerns. Osgood-Schlatter disease, a painful inflammation of the area just below the front of the knee, is particularly common in the early teen years. Knee pain is also a frequent complaint. Your teen's doctor should evaluate any severe or persistent pain of the joints, muscles, or other areas of the body.
Antibiotics Questioned in Care at Life’s End
A yearlong study is raising questions about the widespread use of antibiotics in nursing homes to treat infections in patients with terminal dementia — a treatment that the authors suggest is of dubious value to the patients and may be dangerous in the long run.
Skip to next paragraph
Related
Times Health Guide: Dementia »
Web Link
Patterns of Antimicrobial Use Among Nursing Home Residents With Advanced Dementia (Archives of Internal Medicine)
The study found that two-thirds of the patients received antibiotics and that 40 percent of that group received them in the last two weeks of life.
Antibiotics are often prescribed for illnesses against which they are ineffective, the authors say, but even when they are properly used, the elderly and frail can be particularly susceptible to their side effects. Intravenous administration of the drugs, common in the people in this study, can be extremely uncomfortable.
And there is the risk that widespread antibiotic use can lead to the emergence of drug-resistant germs, a significant and growing public health problem. Previous studies have found that as many as 40 percent of patients in nursing homes harbor drug-resistant bacteria.
For the study, published Feb. 25 in The Archives of Internal Medicine, researchers tracked antibiotic use among 214 patients in 21 nursing homes near Boston. Seventy percent had advanced Alzheimer’s disease, and the rest had other kinds of severe dementia.
Almost half of the prescriptions were for respiratory diseases, and more than a third were for urinary tract infections. Of the 99 patients who died during the course of the study, 52 had received antibiotics in their last eight weeks of life. An editorial accompanying the report says this finding suggests that doctors did not regularly consider whether treatment might be futile.
“It’s important for physicians to address these issues with family members or patient surrogates to determine whether or not they want their loved one to receive antibiotics, knowing that it may cause unnecessary burdens and that we’re not sure it will improve their quality of life or prolong life,” said the lead author, Dr. Erika D’Agata, an assistant professor of medicine at Beth Israel Deaconess Hospital in Boston.
There are two reasons to administer antibiotics, the authors say: to prolong life and to control unpleasant symptoms. There have been no randomized trials, but observational studies suggest that in this population, prescribing antibiotics achieves neither goal. Infections can be painful, but it is not clear that antibiotics provide relief any greater than more conservative treatments like oxygen and pain relievers.
Dr. Paul S. Appelbaum, a professor of psychiatry at Columbia who has published widely on medical ethics and the law, questioned the conclusions. “The apparent suggestion that we should not be treating persons with dementia when they develop infections rests on a normative judgment — that does not flow from these data — that their lives are worth less than the unknown degree of risk of contributing to antibiotic resistance,” Dr. Appelbaum wrote in an e-mail message.
“Although one cannot ask the patients themselves how they feel about this judgment,” he said, “many of their family members and caregivers would disagree, and our society — fortunately, in my view — has not yet reached the point where it is willing to embrace it.”
The authors acknowledge that they had tracked only days of use, and not specific dosages, and that the study of demented patients did not include a comparison group of other long-term-care residents. And, they write, it is yet to be proved that demented patients are more likely than other groups to be reservoirs of resistant organisms.
Still, they continue, infections and fevers are common in end-stage dementia, and the widespread use of antibiotics for these patients poses significant problems given the lack of demonstrable benefits. While the researchers do not suggest that antibiotic treatment be abandoned in patients with advanced dementia, they say programs and guidelines should be established to limit their use.
Skip to next paragraph
Related
Times Health Guide: Dementia »
Web Link
Patterns of Antimicrobial Use Among Nursing Home Residents With Advanced Dementia (Archives of Internal Medicine)
The study found that two-thirds of the patients received antibiotics and that 40 percent of that group received them in the last two weeks of life.
Antibiotics are often prescribed for illnesses against which they are ineffective, the authors say, but even when they are properly used, the elderly and frail can be particularly susceptible to their side effects. Intravenous administration of the drugs, common in the people in this study, can be extremely uncomfortable.
And there is the risk that widespread antibiotic use can lead to the emergence of drug-resistant germs, a significant and growing public health problem. Previous studies have found that as many as 40 percent of patients in nursing homes harbor drug-resistant bacteria.
For the study, published Feb. 25 in The Archives of Internal Medicine, researchers tracked antibiotic use among 214 patients in 21 nursing homes near Boston. Seventy percent had advanced Alzheimer’s disease, and the rest had other kinds of severe dementia.
Almost half of the prescriptions were for respiratory diseases, and more than a third were for urinary tract infections. Of the 99 patients who died during the course of the study, 52 had received antibiotics in their last eight weeks of life. An editorial accompanying the report says this finding suggests that doctors did not regularly consider whether treatment might be futile.
“It’s important for physicians to address these issues with family members or patient surrogates to determine whether or not they want their loved one to receive antibiotics, knowing that it may cause unnecessary burdens and that we’re not sure it will improve their quality of life or prolong life,” said the lead author, Dr. Erika D’Agata, an assistant professor of medicine at Beth Israel Deaconess Hospital in Boston.
There are two reasons to administer antibiotics, the authors say: to prolong life and to control unpleasant symptoms. There have been no randomized trials, but observational studies suggest that in this population, prescribing antibiotics achieves neither goal. Infections can be painful, but it is not clear that antibiotics provide relief any greater than more conservative treatments like oxygen and pain relievers.
Dr. Paul S. Appelbaum, a professor of psychiatry at Columbia who has published widely on medical ethics and the law, questioned the conclusions. “The apparent suggestion that we should not be treating persons with dementia when they develop infections rests on a normative judgment — that does not flow from these data — that their lives are worth less than the unknown degree of risk of contributing to antibiotic resistance,” Dr. Appelbaum wrote in an e-mail message.
“Although one cannot ask the patients themselves how they feel about this judgment,” he said, “many of their family members and caregivers would disagree, and our society — fortunately, in my view — has not yet reached the point where it is willing to embrace it.”
The authors acknowledge that they had tracked only days of use, and not specific dosages, and that the study of demented patients did not include a comparison group of other long-term-care residents. And, they write, it is yet to be proved that demented patients are more likely than other groups to be reservoirs of resistant organisms.
Still, they continue, infections and fevers are common in end-stage dementia, and the widespread use of antibiotics for these patients poses significant problems given the lack of demonstrable benefits. While the researchers do not suggest that antibiotic treatment be abandoned in patients with advanced dementia, they say programs and guidelines should be established to limit their use.
the danger of antibotic
Every year, your family probably faces its share of colds, sore throats, and viruses. When you bring your child to the doctor for these illnesses, do you automatically expect a prescription for antibiotics?
Many parents do. And they're surprised, maybe even angry, if they leave the doctor's office empty-handed — after all, what parent doesn't want their kid to get well as quickly as possible? But your doctor could be doing you and your child a favor by not reaching for the prescription pad.
How Antibiotics Work
Antibiotics, first used in the 1940s, are certainly one of the great advances in medicine. But overprescribing them has resulted in the development of bacteria that don't respond to antibiotics that may have worked in the past. Plus, kids who take antibiotics when they aren't necessary run the risk of adverse reactions, such as stomach upset and diarrhea.
To understand how antibiotics work, it helps to know about the two types of germs that can make people sick: bacteria and viruses. Although certain bacteria and viruses cause diseases with similar symptoms, the ways these two organisms multiply and spread illness are different:
* Bacteria are living organisms existing as single cells. Bacteria are everywhere and most don't cause any harm, and in some cases may be beneficial. Lactobacillus, for example, live in the intestine and help digest food. But some bacteria are harmful and can cause illness by invading the human body, multiplying, and interfering with normal bodily processes. Antibiotics are effective against bacteria because they work to kill these living organisms by stopping their growth and reproduction.
* Viruses, on the other hand, are not alive and cannot exist on their own — they are particles containing genetic material wrapped in a protein coat. Viruses "live," grow, and reproduce only after they've invaded other living cells. Some viruses may be fought off by the body's immune system before they cause illness, but others (colds, flu, and chickenpox, for example) must simply run their course. Viruses do not respond to antibiotics at all.
Why It's Harmful to Overuse Them
Taking antibiotics for colds and other viral illnesses not only won't work, but also has a dangerous side effect: over time, this practice helps create bacteria that have become more of a challenge to kill. Frequent and inappropriate use of antibiotics selects for strains of bacteria that can resist treatment. This is called bacterial resistance. These resistant bacteria require higher doses of medicine or stronger antibiotics to treat. Doctors have even found bacteria that are resistant to some of the most powerful antibiotics available today.
Antibiotic resistance is a widespread problem, and one that the U.S. Centers for Disease Control and Prevention calls "one of the world's most pressing public health problems." Bacteria that were once highly responsive to antibiotics have become increasingly resistant. Among those that are becoming harder to treat are pneumococcal infections (which cause pneumonia, ear infections, sinus infections, and meningitis), skin infections, and tuberculosis.
Taking Antibiotics Safely
So what should you do when your child gets sick? To minimize the risk of bacterial resistance, keep these tips in mind:
* Treat only bacterial infections. Seek advice and ask questions.
Letting milder illnesses (especially those thought to be caused by viruses) run their course to avoid the development of drug-resistant germs may be a good idea — but it's still best to leave what constitutes a "mild illness" up to your doctor. Even if the symptoms don't worsen but linger, take your child to the doctor. At the office, ask questions about whether your child's illness is bacterial or viral, and discuss the risks and benefits of antibiotics. If it's a virus, don't pressure your doctor to prescribe antibiotics, but ask about ways to treat symptoms.
* Use antibiotics as prescribed.
* Don't save antibiotics for next time.
* Never use another person's prescription.
Ask your doctor about ways to treat the symptoms that are making your child uncomfortable, such as a stuffy nose or scratchy throat, without the use of antibiotics. The key to building a good relationship with your doctor is open communication, so work together toward that goal.
Use the medication properly. Antibiotics are only effective if taken for the full amount of time prescribed by the doctor — and they take time to kick in, too, so don't expect your child to feel better after taking the first dose. Most kids take 1 to 2 days to feel a lot better. Similarly, don't let your child take antibiotics longer than prescribed.
And most important, never use antibiotics that have been lying around your home. Never take antibiotics that were prescribed for another family member, either — doses for kids vary, and if your child did have an illness requiring antibiotics, you'd want to make sure you were treating it correctly. Saving antibiotics "for the next time" is a bad idea, too. Any remaining antibiotic should be thrown out as soon as your child has taken the full course of medication.
Help fight antibiotic resistance by taking simple steps to prevent the spread of infections. Encourage hand washing, make sure your kids are up to date on immunizations, and keep kids out of school when sick.
Doctors are aware of increasing antibiotic resistance and are trying to solve the problem. New antibiotics may be on the horizon, but for now antibiotics need to be prescribed and used appropriately.
Many parents do. And they're surprised, maybe even angry, if they leave the doctor's office empty-handed — after all, what parent doesn't want their kid to get well as quickly as possible? But your doctor could be doing you and your child a favor by not reaching for the prescription pad.
How Antibiotics Work
Antibiotics, first used in the 1940s, are certainly one of the great advances in medicine. But overprescribing them has resulted in the development of bacteria that don't respond to antibiotics that may have worked in the past. Plus, kids who take antibiotics when they aren't necessary run the risk of adverse reactions, such as stomach upset and diarrhea.
To understand how antibiotics work, it helps to know about the two types of germs that can make people sick: bacteria and viruses. Although certain bacteria and viruses cause diseases with similar symptoms, the ways these two organisms multiply and spread illness are different:
* Bacteria are living organisms existing as single cells. Bacteria are everywhere and most don't cause any harm, and in some cases may be beneficial. Lactobacillus, for example, live in the intestine and help digest food. But some bacteria are harmful and can cause illness by invading the human body, multiplying, and interfering with normal bodily processes. Antibiotics are effective against bacteria because they work to kill these living organisms by stopping their growth and reproduction.
* Viruses, on the other hand, are not alive and cannot exist on their own — they are particles containing genetic material wrapped in a protein coat. Viruses "live," grow, and reproduce only after they've invaded other living cells. Some viruses may be fought off by the body's immune system before they cause illness, but others (colds, flu, and chickenpox, for example) must simply run their course. Viruses do not respond to antibiotics at all.
Why It's Harmful to Overuse Them
Taking antibiotics for colds and other viral illnesses not only won't work, but also has a dangerous side effect: over time, this practice helps create bacteria that have become more of a challenge to kill. Frequent and inappropriate use of antibiotics selects for strains of bacteria that can resist treatment. This is called bacterial resistance. These resistant bacteria require higher doses of medicine or stronger antibiotics to treat. Doctors have even found bacteria that are resistant to some of the most powerful antibiotics available today.
Antibiotic resistance is a widespread problem, and one that the U.S. Centers for Disease Control and Prevention calls "one of the world's most pressing public health problems." Bacteria that were once highly responsive to antibiotics have become increasingly resistant. Among those that are becoming harder to treat are pneumococcal infections (which cause pneumonia, ear infections, sinus infections, and meningitis), skin infections, and tuberculosis.
Taking Antibiotics Safely
So what should you do when your child gets sick? To minimize the risk of bacterial resistance, keep these tips in mind:
* Treat only bacterial infections. Seek advice and ask questions.
Letting milder illnesses (especially those thought to be caused by viruses) run their course to avoid the development of drug-resistant germs may be a good idea — but it's still best to leave what constitutes a "mild illness" up to your doctor. Even if the symptoms don't worsen but linger, take your child to the doctor. At the office, ask questions about whether your child's illness is bacterial or viral, and discuss the risks and benefits of antibiotics. If it's a virus, don't pressure your doctor to prescribe antibiotics, but ask about ways to treat symptoms.
* Use antibiotics as prescribed.
* Don't save antibiotics for next time.
* Never use another person's prescription.
Ask your doctor about ways to treat the symptoms that are making your child uncomfortable, such as a stuffy nose or scratchy throat, without the use of antibiotics. The key to building a good relationship with your doctor is open communication, so work together toward that goal.
Use the medication properly. Antibiotics are only effective if taken for the full amount of time prescribed by the doctor — and they take time to kick in, too, so don't expect your child to feel better after taking the first dose. Most kids take 1 to 2 days to feel a lot better. Similarly, don't let your child take antibiotics longer than prescribed.
And most important, never use antibiotics that have been lying around your home. Never take antibiotics that were prescribed for another family member, either — doses for kids vary, and if your child did have an illness requiring antibiotics, you'd want to make sure you were treating it correctly. Saving antibiotics "for the next time" is a bad idea, too. Any remaining antibiotic should be thrown out as soon as your child has taken the full course of medication.
Help fight antibiotic resistance by taking simple steps to prevent the spread of infections. Encourage hand washing, make sure your kids are up to date on immunizations, and keep kids out of school when sick.
Doctors are aware of increasing antibiotic resistance and are trying to solve the problem. New antibiotics may be on the horizon, but for now antibiotics need to be prescribed and used appropriately.
Wednesday, July 16, 2008
Side effects
Possible side effects are varied, depend on the antibiotics used and the microbial organisms targeted. Adverse effects can range from fever and nausea to major allergic reactions including photodermatitis.[citation needed] One of the more common side effects is diarrhea, sometimes caused by the anaerobic bacterium Clostridium difficile, which results from the antibiotic disrupting the normal balance of the intestinal flora,[4] Such overgrowth of pathogenic bacteria may be alleviated by ingesting probiotics during a course of antibiotics. [citation needed]. An antibiotic-induced disruption of the population of the bacteria normally present as constituents of the normal vaginal flora may also occur, and may lead to overgrowth of yeast species of the genus Candida in the vulvo-vaginal area. [5] Other side effects can result from interaction with other drugs, such as elevated risk of tendon damage from administration of a quinolone antibiotic with a systemic corticosteroid.
It is a common assertion that some antibiotics can interfere with the efficiency of birth control pills. Although there remain few known cases of complication, the majority of antibiotics do not interfere with contraception, despite widespread misinformation to the contrary.[6]
Antibiotic misuse
Common forms of antibiotic misuse include failure to take the entire prescribed course of the antibiotic, or failure to rest for sufficient recovery allowing clearance from the infecting organism. These practices may cause the development of bacterial populations with antibiotic resistance. Inappropriate antibiotic treatment is another common form of antibiotic misuse. A common example is the use of antibacterial antibiotics to treat viral infections such as the common cold.
Animals
It is estimated that greater than 50% of the antibiotics used in U.S. are given to feed animals (e.g. chickens, pigs and cattle) in the absence of disease.[7] Antibiotic use in food animal production has been associated with the emergence of antibiotic-resistant strains of bacteria including Salmonella spp., Campylobacter spp., Escherichia coli, and Enterococcus spp. Evidence from some US and European studies suggest that these resistant bacteria cause infections in humans that do not respond to commonly prescribed antibiotics. In response to these practices and attendant problems, several organizations (e.g. The American Society for Microbiology (ASM), American Public Health Association (APHA) and the American Medical Association (AMA)) have called for restrictions on antibiotic use in food animal production and an end to all non-therapeutic uses. [citation needed] However, delays in regulatory and legislative actions to limit the use of antibiotics are common, and may include resistance to these changes by industries using or selling antibiotics, as well as time spend on research to establish causal links between antibiotic use and emergence of untreatable bacterial diseases. Today, there are two federal bills (S.742 and H.R. 2562) aimed at phasing out non-therapeutic antibiotics in US food animal production. These bills are endorsed by public health and medical organizations including the American Nurses Association (ANA), the American Academy of Pediatrics (AAP), and the American Public Health Association (APHA). [citation needed]
Humans
One study on respiratory tract infections found "physicians were more likely to prescribe antibiotics to patients who they believed expected them, although they correctly identified only about 1 in 4 of those patients".[8] Multifactorial interventions aimed at both physicians and patients can reduce inappropriate prescribing of antibiotics. [9] Delaying antibiotics for 48 hours while observing for spontaneous resolution of respiratory tract infections may reduce antibiotic usage; however, this strategy may reduce patient satisfaction.[10]
Excessive use of prophylactic antibiotics in travelers may also be classified as misuse.
Antibiotic resistance
Use or misuse of antibiotics may result in the development of antibiotic resistance by the infecting organisms, similar to the development of pesticide resistance in insects. Evolutionary theory of genetic selection requires that as close as possible to 100% of the infecting organisms be killed off to avoid selection of resistance; if a small subset of the population survives the treatment and is allowed to multiply, the average susceptibility of this new population to the compound will be much less than that of the original population, since they have descended from those few organisms which survived the original treatment. This survival often results from an inheritable resistance to the compound which was infrequent in the original population but is now much more frequent in the descendants thus selected entirely from those originally infrequent resistant organisms.
Antibiotic resistance has become a serious problem in both the developed and underdeveloped nations. By 1984 half of the people with active tuberculosis in the United States had a strain that resisted at least one antibiotic. In certain settings, such as hospitals and some child-care locations, the rate of antibiotic resistance is so high that the normal, low cost antibiotics are virtually useless for treatment of frequently seen infections. This leads to more frequent use of newer and more expensive compounds, which in turn leads inexorably to the rise of resistance to those drugs, and a race to discover new and different antibiotics ensues, just to keep us from losing ground in the battle against infection. The fear is that we will eventually fail to keep up in this race, and the time when people did not fear life-threatening bacterial infections will be just a memory of a golden era.
Another example of selection is Staphylococcus aureus, which could be treated successfully with penicillin in the 1940s and 1950s. At present, nearly all strains are resistant to penicillin, and many are resistant to nafcillin, leaving only a narrow selection of drugs such as vancomycin useful for treatment. The situation is worsened by the fact that genes coding for antibiotic resistance can be transferred between bacteria via plasmids, making it possible for bacteria never exposed to an antibiotic to acquire resistance from those which have. The problem of antibiotic resistance is worsened when antibiotics are used to treat disorders in which they have no efficacy, such as the common cold or other viral complaints, and when they are used widely as prophylaxis rather than treatment (as in, for example, animal feeds), because this exposes more bacteria to selection for resistance.
Resistance Modifying Agents
One solution to combat resistance currently being researched is the development of pharmaceutical compounds that would revert multiple antibiotic resistance. These so called resistance modifying agents may target and inhibit MDR mechanisms rendering the bacteria suceptible to antibiotics they were previously resistant to. These compounds targets include among others
- Efflux inhibition(Phe-Arg-β-naphthylamide)[11]
- Beta Lactamase inhibition Augmentin® [12]
Beyond antibiotics
The comparative ease of identifying compounds which safely cured bacterial infections was more difficult to duplicate in treatments of fungal and viral infections. Antibiotic research led to great strides in the knowledge of biochemistry, establishing large differences between the cellular and molecular physiology of the bacterial cell and that of the mammalian cell. This explained the observation that many compounds that are toxic to bacteria are non-toxic to human cells. In contrast, the basic biochemistries of the fungal cell and the mammalian cell are much more similar. This restricts the development and use of therapeutic compounds that attack a fungal cell, while not harming mammalian cells. Similar problems exist in antibiotic treatments of viral diseases. Human viral metabolic biochemistry is very closely similar to human biochemistry, and the possible targets of antiviral compounds are restricted to very few components unique to a mammalian virus.
Research into bacteriophages for use as antibiotics is presently ongoing. Several types of bacteriophage appear to exist that are specific for each bacterial taxonomic group or species.[citation needed] Research into bacteriophages for medicinal use is just beginning, but has led to advances in microscopic imaging.[13] While bacteriophages provide a possible solution to the problem of antibiotic resistance, there is no clinical evidence yet that they can be deployed as therapeutic agents to cure disease.
Phage therapy has been used in the past on humans in the US and Europe during the 1920s and 1930s, but these treatments had mixed results. With the discovery of penicillin in the 1940s, Europe and the US changed therapeutic strategies to using antibiotics. However, in the former Soviet Union phage therapies continued to be studied. In the Republic of Georgia, the Eliava Institute of Bacteriophage, Microbiology & Virology continues to research the use of phage therapy. Various companies and foundations in North America and Europe are currently researching phage therapies. [citation needed] However, phage are living and reproducing; concerns about genetic engineering in freely released viruses currently limits certain aspects of phage therapy.
Bacteriocins are also a growing alternative to the classic small-molecule antibiotics. Different classes of bacteriocins have different potential as therapeutic agents. Small molecule bacteriocins (microcins, for example, and lantibiotics) may be similar to the classic antibiotics; colicin-like bacteriocins are more likely to be narrow-spectrum, demanding new molecular diagnostics prior to therapy but also not raising the specter of resistance to the same degree.
Probiotics are another alternative that goes beyond traditional antibiotics by employing a live culture which may establish itself as a symbiont, competing, inhibiting, or simply interfering with colonization by pathogens. It may produce antibiotics or bacteriocins, essentially providing the drug in vivo and in situ, potentially avoiding the side effects of systemic administration.
References
- ^ How Products Are Made: Antibiotics
- ^ Pelczar, M.J., Chan, E.C.S. and Krieg, N.R. (1999) “Host-Parasite Interaction; Nonspecific Host Resistance”, In: Microbiology Conceptsand Applications, 6th ed., McGraw-Hill Inc., New York, U.S.A. pp. 478-479.
- ^ Robert Berkow (ed.) The Merck Manual of Medical Information - Home Edition. Pocket (September 1999), ISBN 0-671-02727-1.
- ^ University of Michigan Health System: Antibiotic-Associated Diarrhea, November 26, 2006
- ^ Pirotta MV, Garland SM (2006). "Genital Candida species detected in samples from women in Melbourne, Australia, before and after treatment with antibiotics". J Clin Microbiol. 44: 3213-3217. PMID 16954250.
- ^ Planned Parenthood: Does taking antibiotics make the pill less effective?, July 15, 2004
- ^ Mellon, M et al. (2001) Hogging It!: Estimates of Antimicrobial Abuse in Livestock, 1st ed. Cambridge, MA: Union of Concerned Scientists.
- ^ Ong S, Nakase J, Moran GJ, Karras DJ, Kuehnert MJ, Talan DA (2007). "Antibiotic use for emergency department patients with upper respiratory infections: prescribing practices, patient expectations, and patient satisfaction". Annals of emergency medicine 50 (3): 213-20. DOI:10.1016/j.annemergmed.2007.03.026. PMID 17467120.
- ^ Metlay JP, Camargo CA, MacKenzie T, et al (2007). "Cluster-randomized trial to improve antibiotic use for adults with acute respiratory infections treated in emergency departments". Annals of emergency medicine 50 (3): 221-30. DOI:10.1016/j.annemergmed.2007.03.022. PMID 17509729.
- ^ Spurling G, Del Mar C, Dooley L, Foxlee R (2007). "Delayed antibiotics for respiratory infections". Cochrane database of systematic reviews (Online) (3): CD004417. DOI:10.1002/14651858.CD004417.pub3. PMID 17636757.
- ^ B. Marquez. (2005). Bacterial efflux systems and efflux pumps inhibitors. Biochimie87 1137–1147
- ^ S. Gibbons (2004) Anti-staphylococcal plant natural products Nat. Prod. Rep., 21, 263-277
- ^ Purdue University "Biologists build better software, beat path to viral knowledge", see Imaging of Epsilon 15, a virus that infects the bacterium Salmonella News report
See also
External links
Wikimedia Commons has media related to:
- Antibiotic News from Genome News Network (GNN)
- Are Antibiotics Killing Us? -Discover Magazine
- JAAPA: New antibiotics useful in primary care
- A new method for controlling bacterial activity without antibiotics - Research conducted at the Hebrew University
- BURDEN of Resistance and Disease in European Nations
- Antibiogram technique video
Resources
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
antibiotics that are used during cancer treatment
Description
The common antibiotics that are used during cancer treatment include:
* Atovaquone (Mapren): antiprotozoal drug used to prevent and treat a very serious type of pneumonia called Pneumocystis carinii pneumonia (PCP), in individuals who experience serious side effects with SMZ-TMP (Sulfamethoxazole/Trimethoprim, brand name Bactrim).
* Aztreonam (Azactam): monobactam antibiotic used to treat gram-negative bacterial infections of the urinary and lower respiratory tracts and the female organs, and infections that are present throughout the body (systemic infections or septicemia).
* Cefepime (Maxipime), ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime), and ceftriaxone sodium (Rocephin): members of a group of antibiotics called cephalosporins used to treat bacterial infections of the urinary and lower respiratory tracts, and infections of the skin, bones, joints, pelvis, and abdomen.
* Ciprofloxacin (Cipro): fluoroquinolone antibiotic used to treat certain gram-negative and gram-positive bacteria and some mycobacteria.
* Clindamycin phosphate (Cleocin): used to treat gram-positive and gram-negative bacterial infections and, in individuals who are allergic to sulfadiazine, toxoplasmosis caused by a parasitic protozoa.
* Gentamicin (gentamycin) sulfate (generic name product, Garamycin, G-Mycin, Jenamicin): aminoglycoside antibiotic used to treat serious infections by many gram-negative bacteria that cannot be treated with other medicines.
* Metronidazole hydrochloride (Flagyl, Metric 21, Metro I.V., Protostat): used for anaerobic bacteria and protozoa.
* Pentamidine (generic name product, Pentam 300): used to treat PCP if serious side effects develop with SMZ-TMP.
* Pyrimethamine (Daraprim): antiprotozoal medicine used together with sulfadiazine to treat toxoplasmosis; or in combination with other medicines for treating mild to moderate PCP, in individuals who cannot tolerate the standard treatment.
* Sulfadiazine (generic name product): sulfonamide antibiotic used with pyrimethamine to treat toxoplasmosis.
* Sulfamethoxazole-Trimethoprim (SMZ-TMP) (generic name product, Bactrim, Cofatrim Forte, Cotrim, Septra, Sulfatrim): the sulfonamide antibiotic, sulfamethoxazole, used in combination with trimethoprim, to prevent and treat PCP and bacterial infections, such as bronchitis and middle ear and urinary tract infections.
* Trimethoprim (generic name product, Proloprim, Trimpex): primarily used to prevent or treat urinary tract infections.
* Vancomycin hydrochloride (generic name product, Vancocin): glycopeptide antibiotic used to treat a variety of serious gram-positive bacterial infections for which other medicines are ineffective, including strains of Staphylococcus that are resistant to most oral antibiotics.
Most of these antibiotics kill bacteria by preventing them from making protein for their cell walls. Ciprofloxacin and metronidazole prevent bacteria from reproducing by interfering with their ability to make new DNA. All of these drugs are approved for prescription by the U.S. Food and Drug Administration.
Recommended Dosage
Dosages of antibiotics depend on the individual, the infection that is being treated, and the presence of other medical conditions. For children, the dosage usually is based on body weight and is lower than the adult dosage. To be effective, an entire treatment with antibiotics must be completed, even if the symptoms of infection have disappeared. Furthermore, it is important to keep the level of antibiotic in the body at a constant level during treatment. Therefore, the drug should be taken on a regular schedule. If a dose is missed, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped. Doubling up doses is generally not recommended.
Average adult dosages of common antibiotics for cancer patients are as follows:
* Atovaquone: for PCP treatment, 750 mg oral suspension twice a day, or tablets three times per day, for 21 days; for PCP prevention, 1,500 mg oral suspension, once a day; must be taken with balanced meals.
* Aztreonam: 1–2 gm every 6–12 hours, injected into a vein, over a 20–60 minute-period.
* Cefepime: 500 mg to 2 gm, injected into a vein or muscle, every 8–12 hours for 7–10 days.
* Ceftazidime: 250 mg to 2 gm, injected into a vein or muscle, every 8–12 hours.
* Ceftriaxone: 1–2 gm, injected into a vein or muscle, every 24 hours.
* Ciprofloxacin: 500–750 mg of the tablet or suspension, every 12 hours, for 3–28 days, taken two hours after meals with 8 oz of water; bone and joint infections usually are treated for at least 4–6 weeks; 200–400 mg injected every 8–12 hours.
* Clindamycin: 150–300 mg of capsule or solution, every six hours; 300–600 mg every six to eight hours or 900 mg every eight hours, injected into a vein or muscle.
* Gentamicin: dosage determined by body weight, every 8–24 hours for at least 7–10 days, injected into a vein or muscle.
* Metronidazole: for bacterial infections, 7.5 mg per kg (3.4 mg per lb) of body weight up to a maximum of 1 gm, every six hours for at least seven days (capsules or tablets); 15 mg per kg (6.8 mg per lb) for the first dose, followed by half that dosage every six hours for at least seven days (injected into a vein); for protozoal infections caused by amebas, 500–750 mg of oral medicine, three times per day for 5–10 days; for trichomoniasis, 2 gm for one day or 250 mg three times per day for seven days (oral medicine); extended-release tablets for vaginal bacterial infections, 750 mg once a day for seven days.
* Pentamidine: for treating PCP, 4 mg per kg (1.8 mg per lb) of body weight, once per day for 14–21 days, injected into a vein over one to two hours, while lying down.
* Pyrimethamine: for toxoplasmosis, 25–200 mg tablets, taken with other medicine, for several weeks.
* Sulfadiazine: for bacterial and protozoal infections, 2–4 gm for the first dose, followed by 1 gm every four to six hours (tablets).
* SMZ-TMP: 800 mg of sulfamethoxazole and 160 mg of trimethoprim, (tablet or oral suspension), every 12 hours for bacterial infections and every 24 hours for prevention of PCP; dosage based on body weight for PCP treatment; injections based on body weight, every six, eight or 12 hours for bacterial infections and every six hours for PCP treatment.
* Trimethoprim: 100 mg tablet every 12 hours for 10 days; for prevention of urinary tract infections, once a day for a long period.
* Vancomycin: 7.5 mg per kg (3.4 mg per lb) of body weight, or 500 mg–1 gram, injected or taken orally, every 6–12 hours.
Precautions
Stomach or intestinal problems or colitis (inflammation of the colon) may affect the use of:
* Atovaquone
* Cephalosporins
* Clindamycin
Kidney or liver disease may affect the use of:
* Aztreonam
* Cefepime
* Ceftazidime
* Ciprofloxacin
* Clindamycin
* Gentamicin
* Metronidazole
* Pentamidine
* Pyrimethamine
* Sulfadiazine
* SMZ-TMP
* Trimethoprim
* Vancomycin
Central nervous system or seizure disorders may affect the use of:
* Ciprofloxacin
* Metronidazole
* Pyrimethamine
Anemia (low red blood cell count) or other blood disorders may affect the use of:
* Metronidazole
* Pentamidine
* Pyrimethamine
* Sulfadiazine
* SMZ-TMP
* Trimethoprim
Ciprofloxacin may not be suitable for individuals with tendinitis or with skin sensitivities to sunlight. Gentamicin may not be suitable for people with hearing problems, myasthenia gravis, or Parkinson's disease. Metronidazole may not be suitable for individuals with heart disease, oral or vaginal yeast infections, or a history of alcoholism. Pentamidine may not be suitable for individuals with heart disease, bleeding disorders, or low blood pressure. Pentamidine may affect blood sugar levels, making control of diabetes mellitus or hypoglycemia (low blood sugar) difficult. Vancomycin may not be appropriate for individuals with hearing problems.
Many antibiotics should not be taken during pregnancy or while breast-feeding. Older individuals may be more susceptible to the side effects of sulfadiazine, SMZ-TMP, or trimethoprim.
Side Effects
Some individuals may have allergic reactions to antibiotics. If symptoms of an allergic reaction (such as rash, shortness of breath, swelling of the face and neck), severe diarrhea, or abdominal cramping occur, the antibiotic should be stopped and the individual should seek medical advice.
Because antibiotics can affect bacteria that are beneficial, as well as those that are harmful, women may become susceptible to infections by fungi when taking antibiotics. Vaginal itching or discharge may be symptoms of such infections. All patients may develop oral fungal infections of the mouth, indicated by white plaques in the mouth.
Injected antibiotics may result in irritation, pain, tenderness, or swelling in the vein used for injection. Antibiotics used in cancer patients may have numerous side effects, both minor and severe; however, most side effects are uncommon or rare.
The more common side effects of atovaquone, aztreonam, cephalosporins, ciprofloxacin, clindamycin, gentamicin, metronidazole, and SMZ-TMP include:
* nausea and vomiting
* diarrhea
* loss of appetite Eating active cultured yogurt may help counteract diarrhea, but if a patient has low white blood cells, this remedy is not recommended. For mild diarrhea with cephalosporins, only diarrhea medicines containing kaolin or attapulgite should be taken. With clindamycin, diarrhea medicines containing attapulgite should be taken several hours before or after the oral antibiotic. Diarrhea following antibiotics like clindamycin may indicate a bacterial infection that needs additional therapy, and a physicians hould be consulted.
Other side effects of atovaquone may include:
* fever
* skin rash
* cough
* headache
* insomnia
Other side effects of ciprofloxacin may include:
* abdominal pain
* increase in blood tests for kidney function
* dizziness or light-headedness
* inflammation or tearing of a tendon
* drowsiness
* insomnia
Other common side effects of clindamycin include abdominal pain and fever. Side effects may occur up to several weeks after treatment with this medicine.
Gentamicin and vancomycin may cause serious side effects, particularly in elderly individuals and newborn infants. These include kidney damage and damage to the auditory nerve that controls hearing. Other, more common side effects of gentamicin may include:
* changes in urination
* increased thirst
* muscle twitching or seizures
* headache
* lethargy
When gentamicin is injected into a muscle, vein, or the spinal fluid, the following side effects may occur:
* leg cramps
* skin rash
* fever
* seizures Side effects from gentamicin may develop up to several weeks after the medicine is stopped.
More common side effects of metronidazole include:
* mouth dryness
* unpleasant or metallic taste
* dizziness or light-headedness
* headache
* stomach pain Sugarless candy or gum, bits of ice, or a saliva substitute may relieve symptoms of dry mouth.
Pentamidine, pyrimethamine, sulfonamides, SMZTMP, and trimethoprim can lower the number of white blood cells, resulting in an increased risk of infection. These drugs also can lower the number of blood platelets that are important for blood clotting. Thus, there is an increased risk of bleeding or bruising while taking these drugs.
Serious side effects of pentamidine may include:
* heart problems
* low blood pressure
* high or low blood sugar
* other blood problems
* decrease in urination
* sore throat and fever
* sharp pain in upper abdomen Some of these symptoms may not occur until several months after treatment with pentamidine.
Pyrimethamine and trimethoprim may lower the red blood cell count, causing anemia. Leucovorin or the vitamin folic acid may be prescribed for anemia.
Some individuals become more sensitive to sunlight when taking sulfonamides, SMZ-TMP, or trimethoprim. Other common side effects of sulfonamides and SMZTMP include:
* dizziness
* itching
* skin rash
* headache
* mouth sores or swelling of the tongue
* fatigue
If vancomycin is injected into a vein too quickly, it can cause flushing and a rash over the neck, face, and chest, wheezing or difficulty breathing, and a dangerous decrease in blood pressure.
Interactions
Many prescription and non-prescription medicines can interact with these antibiotics. Therefore, it is important to consult a complete list of known drug interactions. Among the more common or dangerous interactions:
* Antibiotics that lower the number of blood platelets, with blood thinners (anticoagulants), such as warfarin
* Aztreonam and metronidazole with alcohol; it is important not to consume alcohol until at least three days after treatment with these antibiotics
* Ciprofloxacin with antacids, iron supplements, or caffeine
* Pentamidine or pyrimethamine with previous treatments with x rays or cancer medicines (increased risk of blood cell damage)
* Trimethoprim with diuretics to remove excess fluid in the elderly
Many medicines can increase the risk of hearing or kidney damage from gentamicin. These include:
* cisplatin
* combination pain medicine with acetaminophen and aspirin or other salicylates (taken regularly in large amounts)
* cyclosporine
* inflammation or pain medicine, except narcotics
* lithium
* methotrexate
* other medicines for infection
The following drugs may increase the risk of liver effects with sulfadiazine or SMZ-TMP:
* acetaminophen, long-term, high-dose (eg Tylenol)
* birth control pills containing estrogens
* disulfiram (Antabuse)
* other medicines for infection
Resources
Books
American Cancer Society. Consumers Guide to Cancer Drugs. Atlanta: Jones and Bartlett, 2000.
Other
American Cancer Society. Cancer Drugs. Cancer Resource Center. 2000. [cited May 27, 2001]. .
American Cancer Society. Infections in Individuals with Cancer. Cancer Resource Center. 30 Sep. 1999. [cited May 27, 2001]. .
MEDLINEplus Drug Information. U.S. National Library of Medicine. 24 Jan. 2001. [cited May 22, 2001]. .
The common antibiotics that are used during cancer treatment include:
* Atovaquone (Mapren): antiprotozoal drug used to prevent and treat a very serious type of pneumonia called Pneumocystis carinii pneumonia (PCP), in individuals who experience serious side effects with SMZ-TMP (Sulfamethoxazole/Trimethoprim, brand name Bactrim).
* Aztreonam (Azactam): monobactam antibiotic used to treat gram-negative bacterial infections of the urinary and lower respiratory tracts and the female organs, and infections that are present throughout the body (systemic infections or septicemia).
* Cefepime (Maxipime), ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime), and ceftriaxone sodium (Rocephin): members of a group of antibiotics called cephalosporins used to treat bacterial infections of the urinary and lower respiratory tracts, and infections of the skin, bones, joints, pelvis, and abdomen.
* Ciprofloxacin (Cipro): fluoroquinolone antibiotic used to treat certain gram-negative and gram-positive bacteria and some mycobacteria.
* Clindamycin phosphate (Cleocin): used to treat gram-positive and gram-negative bacterial infections and, in individuals who are allergic to sulfadiazine, toxoplasmosis caused by a parasitic protozoa.
* Gentamicin (gentamycin) sulfate (generic name product, Garamycin, G-Mycin, Jenamicin): aminoglycoside antibiotic used to treat serious infections by many gram-negative bacteria that cannot be treated with other medicines.
* Metronidazole hydrochloride (Flagyl, Metric 21, Metro I.V., Protostat): used for anaerobic bacteria and protozoa.
* Pentamidine (generic name product, Pentam 300): used to treat PCP if serious side effects develop with SMZ-TMP.
* Pyrimethamine (Daraprim): antiprotozoal medicine used together with sulfadiazine to treat toxoplasmosis; or in combination with other medicines for treating mild to moderate PCP, in individuals who cannot tolerate the standard treatment.
* Sulfadiazine (generic name product): sulfonamide antibiotic used with pyrimethamine to treat toxoplasmosis.
* Sulfamethoxazole-Trimethoprim (SMZ-TMP) (generic name product, Bactrim, Cofatrim Forte, Cotrim, Septra, Sulfatrim): the sulfonamide antibiotic, sulfamethoxazole, used in combination with trimethoprim, to prevent and treat PCP and bacterial infections, such as bronchitis and middle ear and urinary tract infections.
* Trimethoprim (generic name product, Proloprim, Trimpex): primarily used to prevent or treat urinary tract infections.
* Vancomycin hydrochloride (generic name product, Vancocin): glycopeptide antibiotic used to treat a variety of serious gram-positive bacterial infections for which other medicines are ineffective, including strains of Staphylococcus that are resistant to most oral antibiotics.
Most of these antibiotics kill bacteria by preventing them from making protein for their cell walls. Ciprofloxacin and metronidazole prevent bacteria from reproducing by interfering with their ability to make new DNA. All of these drugs are approved for prescription by the U.S. Food and Drug Administration.
Recommended Dosage
Dosages of antibiotics depend on the individual, the infection that is being treated, and the presence of other medical conditions. For children, the dosage usually is based on body weight and is lower than the adult dosage. To be effective, an entire treatment with antibiotics must be completed, even if the symptoms of infection have disappeared. Furthermore, it is important to keep the level of antibiotic in the body at a constant level during treatment. Therefore, the drug should be taken on a regular schedule. If a dose is missed, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped. Doubling up doses is generally not recommended.
Average adult dosages of common antibiotics for cancer patients are as follows:
* Atovaquone: for PCP treatment, 750 mg oral suspension twice a day, or tablets three times per day, for 21 days; for PCP prevention, 1,500 mg oral suspension, once a day; must be taken with balanced meals.
* Aztreonam: 1–2 gm every 6–12 hours, injected into a vein, over a 20–60 minute-period.
* Cefepime: 500 mg to 2 gm, injected into a vein or muscle, every 8–12 hours for 7–10 days.
* Ceftazidime: 250 mg to 2 gm, injected into a vein or muscle, every 8–12 hours.
* Ceftriaxone: 1–2 gm, injected into a vein or muscle, every 24 hours.
* Ciprofloxacin: 500–750 mg of the tablet or suspension, every 12 hours, for 3–28 days, taken two hours after meals with 8 oz of water; bone and joint infections usually are treated for at least 4–6 weeks; 200–400 mg injected every 8–12 hours.
* Clindamycin: 150–300 mg of capsule or solution, every six hours; 300–600 mg every six to eight hours or 900 mg every eight hours, injected into a vein or muscle.
* Gentamicin: dosage determined by body weight, every 8–24 hours for at least 7–10 days, injected into a vein or muscle.
* Metronidazole: for bacterial infections, 7.5 mg per kg (3.4 mg per lb) of body weight up to a maximum of 1 gm, every six hours for at least seven days (capsules or tablets); 15 mg per kg (6.8 mg per lb) for the first dose, followed by half that dosage every six hours for at least seven days (injected into a vein); for protozoal infections caused by amebas, 500–750 mg of oral medicine, three times per day for 5–10 days; for trichomoniasis, 2 gm for one day or 250 mg three times per day for seven days (oral medicine); extended-release tablets for vaginal bacterial infections, 750 mg once a day for seven days.
* Pentamidine: for treating PCP, 4 mg per kg (1.8 mg per lb) of body weight, once per day for 14–21 days, injected into a vein over one to two hours, while lying down.
* Pyrimethamine: for toxoplasmosis, 25–200 mg tablets, taken with other medicine, for several weeks.
* Sulfadiazine: for bacterial and protozoal infections, 2–4 gm for the first dose, followed by 1 gm every four to six hours (tablets).
* SMZ-TMP: 800 mg of sulfamethoxazole and 160 mg of trimethoprim, (tablet or oral suspension), every 12 hours for bacterial infections and every 24 hours for prevention of PCP; dosage based on body weight for PCP treatment; injections based on body weight, every six, eight or 12 hours for bacterial infections and every six hours for PCP treatment.
* Trimethoprim: 100 mg tablet every 12 hours for 10 days; for prevention of urinary tract infections, once a day for a long period.
* Vancomycin: 7.5 mg per kg (3.4 mg per lb) of body weight, or 500 mg–1 gram, injected or taken orally, every 6–12 hours.
Precautions
Stomach or intestinal problems or colitis (inflammation of the colon) may affect the use of:
* Atovaquone
* Cephalosporins
* Clindamycin
Kidney or liver disease may affect the use of:
* Aztreonam
* Cefepime
* Ceftazidime
* Ciprofloxacin
* Clindamycin
* Gentamicin
* Metronidazole
* Pentamidine
* Pyrimethamine
* Sulfadiazine
* SMZ-TMP
* Trimethoprim
* Vancomycin
Central nervous system or seizure disorders may affect the use of:
* Ciprofloxacin
* Metronidazole
* Pyrimethamine
Anemia (low red blood cell count) or other blood disorders may affect the use of:
* Metronidazole
* Pentamidine
* Pyrimethamine
* Sulfadiazine
* SMZ-TMP
* Trimethoprim
Ciprofloxacin may not be suitable for individuals with tendinitis or with skin sensitivities to sunlight. Gentamicin may not be suitable for people with hearing problems, myasthenia gravis, or Parkinson's disease. Metronidazole may not be suitable for individuals with heart disease, oral or vaginal yeast infections, or a history of alcoholism. Pentamidine may not be suitable for individuals with heart disease, bleeding disorders, or low blood pressure. Pentamidine may affect blood sugar levels, making control of diabetes mellitus or hypoglycemia (low blood sugar) difficult. Vancomycin may not be appropriate for individuals with hearing problems.
Many antibiotics should not be taken during pregnancy or while breast-feeding. Older individuals may be more susceptible to the side effects of sulfadiazine, SMZ-TMP, or trimethoprim.
Side Effects
Some individuals may have allergic reactions to antibiotics. If symptoms of an allergic reaction (such as rash, shortness of breath, swelling of the face and neck), severe diarrhea, or abdominal cramping occur, the antibiotic should be stopped and the individual should seek medical advice.
Because antibiotics can affect bacteria that are beneficial, as well as those that are harmful, women may become susceptible to infections by fungi when taking antibiotics. Vaginal itching or discharge may be symptoms of such infections. All patients may develop oral fungal infections of the mouth, indicated by white plaques in the mouth.
Injected antibiotics may result in irritation, pain, tenderness, or swelling in the vein used for injection. Antibiotics used in cancer patients may have numerous side effects, both minor and severe; however, most side effects are uncommon or rare.
The more common side effects of atovaquone, aztreonam, cephalosporins, ciprofloxacin, clindamycin, gentamicin, metronidazole, and SMZ-TMP include:
* nausea and vomiting
* diarrhea
* loss of appetite Eating active cultured yogurt may help counteract diarrhea, but if a patient has low white blood cells, this remedy is not recommended. For mild diarrhea with cephalosporins, only diarrhea medicines containing kaolin or attapulgite should be taken. With clindamycin, diarrhea medicines containing attapulgite should be taken several hours before or after the oral antibiotic. Diarrhea following antibiotics like clindamycin may indicate a bacterial infection that needs additional therapy, and a physicians hould be consulted.
Other side effects of atovaquone may include:
* fever
* skin rash
* cough
* headache
* insomnia
Other side effects of ciprofloxacin may include:
* abdominal pain
* increase in blood tests for kidney function
* dizziness or light-headedness
* inflammation or tearing of a tendon
* drowsiness
* insomnia
Other common side effects of clindamycin include abdominal pain and fever. Side effects may occur up to several weeks after treatment with this medicine.
Gentamicin and vancomycin may cause serious side effects, particularly in elderly individuals and newborn infants. These include kidney damage and damage to the auditory nerve that controls hearing. Other, more common side effects of gentamicin may include:
* changes in urination
* increased thirst
* muscle twitching or seizures
* headache
* lethargy
When gentamicin is injected into a muscle, vein, or the spinal fluid, the following side effects may occur:
* leg cramps
* skin rash
* fever
* seizures Side effects from gentamicin may develop up to several weeks after the medicine is stopped.
More common side effects of metronidazole include:
* mouth dryness
* unpleasant or metallic taste
* dizziness or light-headedness
* headache
* stomach pain Sugarless candy or gum, bits of ice, or a saliva substitute may relieve symptoms of dry mouth.
Pentamidine, pyrimethamine, sulfonamides, SMZTMP, and trimethoprim can lower the number of white blood cells, resulting in an increased risk of infection. These drugs also can lower the number of blood platelets that are important for blood clotting. Thus, there is an increased risk of bleeding or bruising while taking these drugs.
Serious side effects of pentamidine may include:
* heart problems
* low blood pressure
* high or low blood sugar
* other blood problems
* decrease in urination
* sore throat and fever
* sharp pain in upper abdomen Some of these symptoms may not occur until several months after treatment with pentamidine.
Pyrimethamine and trimethoprim may lower the red blood cell count, causing anemia. Leucovorin or the vitamin folic acid may be prescribed for anemia.
Some individuals become more sensitive to sunlight when taking sulfonamides, SMZ-TMP, or trimethoprim. Other common side effects of sulfonamides and SMZTMP include:
* dizziness
* itching
* skin rash
* headache
* mouth sores or swelling of the tongue
* fatigue
If vancomycin is injected into a vein too quickly, it can cause flushing and a rash over the neck, face, and chest, wheezing or difficulty breathing, and a dangerous decrease in blood pressure.
Interactions
Many prescription and non-prescription medicines can interact with these antibiotics. Therefore, it is important to consult a complete list of known drug interactions. Among the more common or dangerous interactions:
* Antibiotics that lower the number of blood platelets, with blood thinners (anticoagulants), such as warfarin
* Aztreonam and metronidazole with alcohol; it is important not to consume alcohol until at least three days after treatment with these antibiotics
* Ciprofloxacin with antacids, iron supplements, or caffeine
* Pentamidine or pyrimethamine with previous treatments with x rays or cancer medicines (increased risk of blood cell damage)
* Trimethoprim with diuretics to remove excess fluid in the elderly
Many medicines can increase the risk of hearing or kidney damage from gentamicin. These include:
* cisplatin
* combination pain medicine with acetaminophen and aspirin or other salicylates (taken regularly in large amounts)
* cyclosporine
* inflammation or pain medicine, except narcotics
* lithium
* methotrexate
* other medicines for infection
The following drugs may increase the risk of liver effects with sulfadiazine or SMZ-TMP:
* acetaminophen, long-term, high-dose (eg Tylenol)
* birth control pills containing estrogens
* disulfiram (Antabuse)
* other medicines for infection
Resources
Books
American Cancer Society. Consumers Guide to Cancer Drugs. Atlanta: Jones and Bartlett, 2000.
Other
American Cancer Society. Cancer Drugs. Cancer Resource Center. 2000. [cited May 27, 2001]. .
American Cancer Society. Infections in Individuals with Cancer. Cancer Resource Center. 30 Sep. 1999. [cited May 27, 2001]. .
MEDLINEplus Drug Information. U.S. National Library of Medicine. 24 Jan. 2001. [cited May 22, 2001]. .
anti-infectives
Antibiotics may be informally defined as the subgroup of anti-infectives derived from bacterial sources and used to treat bacterial infections.
Purpose
Antibiotics are used for treatment or prevention of bacterial infection. Other classes of drugs, most notably the sulfonamides, may be effective antibacterials. Similarly, some antibiotics may have secondary uses, such as the use of demeclocycline (Declomycin, a tetracycline derivative) to treat the syndrome of inappropriate antidiuretic hormone (SIADH) secretion. Other antibiotics may be useful in treating protozoal infections.
Description
Although there are several classification schemes for antibiotics, based on bacterial spectrum (broad versus narrow), route of administration (injectable versus oral versus topical), or type of activity (bactericidal versus bacteriostatic), the most useful is based on chemical structure. Antibiotics within a structural class will generally show similar patterns of effectiveness, toxicity, and allergic potential.
Penicillins
The penicillins are the oldest class of antibiotics and have a common chemical structure that they share with the cephalosporins. The two groups are classed as the beta-lactam antibiotics, and are generally bacteriocidal—that is, they kill bacteria rather than inhibit growth. The penicillins can be further subdivided. The natural penicillins are based on the original penicillin G structure; penicillinase-resistant penicillins, notably methicillin and oxacillin, are active even in the presence of the bacterial enzyme that inactivates most natural penicillins. Aminopenicillins such as ampicillin and amoxicillin have an extended spectrum of action compared with the natural penicillins; extended spectrum penicillins are effective against a wider range of bacteria. These generally include coverage for Pseudomonas aeruginosa and may provide the penicillin in combination with a penicillinase inhibitor.
Cephalosporins
Cephalosporins and the closely related cephamycins and carbapenems, like the penicillins, contain a beta-lactam chemical structure. Consequently, there are patterns of cross-resistance and cross-allergenicity among the drugs in these classes. The "cepha" drugs are among the most diverse classes of antibiotics, and are themselves subgrouped into first, second, and third generations. Each generation has a broader spectrum of activity than the one before. In addition, cefoxitin (Mefoxin), a cephamycin, is highly active against anaerobic bacteria, which makes it useful in prevention and treatment of infections of the intestines. The third generation drugs, cefotaxime, ceftizoxime, ceftriaxone, and others, cross the blood-brain barrier and may be used to treat meningitis and encephalitis. Cephalosporins are the usually preferred agents for prevention of infection during surgery.
Fluroquinolones
The fluroquinolones are synthetic antibacterial agents, and are not derived from bacteria. They are included here because they can be readily interchanged with traditional antibiotics. An earlier, related class of antibacterial agents, the quinolones, were not well absorbed, and could be used only to treat urinary tract infections. The fluroquinolones, which are based on the older group, are broad-spectrum bactericidal drugs that are chemically unrelated to the penicillins or the cephalosporins. They are well distributed into bone tissue, and so well absorbed that in general they are as effective by the oral route as by intravenous infusion.
Tetracyclines
Tetracyclines got their name because they share a chemical structure having four rings. They are derived from a species of Streptomyces bacteria. Broad-spectrum bacteriostatic agents, the tetracyclines may be effective against a wide variety of microorganisms, including rickettsia and amebic parasites.
Macrolides
The macrolide antibiotics are derived from Streptomyces bacteria, and got their name because they all have a macrocyclic lactone chemical structure. Erythromycin, the prototype of this class, has a spectrum and use similar to penicillin. Newer members of the group, azithromycin and clarithyromycin, are particularly useful for their high level of lung penetration. Clarithromycin has been widely used to treat Helicobacter pylori infections, the cause of stomach ulcers. For people who are allergic to penicillin, erythromycin is a valuable alternative. But, unlike penicillin, erythromycin can be very irritating
Different antibiotics destroy bacteria in different ways. Some short-circuit the processes by which bacteria receive energy. Others disturb the structure of the bacterial cell wall, as shown in the illustration above. Still others interfere with the production of essential proteins. (
both to the stomach when given by mouth, or to veins when given by injection.
Other Classes
Other classes of antibiotics include the aminoglycosides, which are particularly useful for their effectiveness in treating Pseudomonas aeruginosa infections, and the lincosamindes, clindamycin and lincomycin, which are highly active against anaerobic pathogens. In addition, other individual drugs are available that may have utility in specific infections.
Recommended Dosage
Dosage varies with drug, route of administration, pathogen, site of infection, and severity. Additional considerations include renal (kidney) function, age of patient, and other factors. Patients should consult manufac turers' recommendations or ask their doctors.
Side Effects
All antibiotics cause risk of overgrowth by non-susceptible bacteria. Manufacturers list other major hazards by class; however, the health care provider should review each drug individually to assess the degree of risk. Generally, breastfeeding is not recommended while taking antibiotics because of risk of alteration to infant's intestinal flora, and risk of masking infection in the infant. Excessive or inappropriate use may promote growth of resistant pathogens.
- Penicillins. Hypersensitivity may be common, and cross allergenicity with cephalosporins has been reported. Penicillins are classed as category B during pregnancy.
- Cephalosporins. Several cephalosporins and related compounds have been associated with seizures. Cefmetazole, cefoperazone, cefotetan and ceftriaxone may be associated with a fall in prothrombin activity and coagulation abnormalities. Pseudomembranous colitis (inflammation of the colon) has been reported with cephalosporins and other broad spectrum antibiotics. Some drugs in this class may cause renal toxicity. Pregnancy category B.
- Fluoroquinolones. Lomefloxacin has been associated with increased photosensitivity. All drugs in this class have been associated with convulsions. Pregnancy category C.
- Tetracyclines. Demeclocycline may cause increased photosensitivity. Minocycline may cause dizziness. Children under the age of eight should not use tetracyclines, and specifically during periods of tooth development. Oral tetracyclines bind to anions such as calcium and iron. Although doxycycline and minocycline may be taken with meals, patients are advised to take other tetracycline antibiotics on an empty stomach, and not to take the drugs with milk or other calcium-rich foods. Expired tetracycline should never be administered. Pregnancy category D; use during pregnancy may cause alterations in bone development.
- Macrolides. Erythromycin may aggravate the weakness of patients with myasthenia gravis. Azithromycin has, rarely, been associated with allergic reactions, including angioedema, anaphylaxis, and dermatologic reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Oral erythromycin may be highly irritating to the stomach and may cause severe phlebitis (inflammation of the vein) when given by injection. These drugs should be used with caution in patients with liver dysfunction. Pregnancy category B: Azithromycin, erythromycin. Pregnancy category C: Clarithromycin, dirithromycin, troleandomycin.
- Aminoglycosides. This class of drugs causes kidney and hearing problems. These problems can occur even with normal doses. Dosing should be based on renal function, with periodic testing of both kidney function and hearing. Pregnancy category D.
Interactions
Use of all antibiotics may temporarily reduce the effectiveness of birth control pills; alternative birth control methods should be used while taking these medications. Antacids should be avoided while on tetracyclines as the calcium can impair absorption of this antibiotic class. For this reason, tetracyclines should not be taken just before or after consuming foods rich in calcium or iron. Consult specialized references for additional interactions to specific antibiotics.
Recommended Usage
To minimize risk of adverse reactions and development of resistant strains of bacteria, antibiotics should be restricted to use in cases where there is either known or a reasonable presumption of bacterial infection. The use of antibiotics in viral infections is to be avoided. Avoid use of fluroquinolones for trivial infections.
In severe infections, presumptive therapy with a broad-spectrum antibiotic such as a third generation cephalosporin may be appropriate. Treatment should be changed to a narrow spectrum agent as soon as the pathogen has been identified. After 48 hours of treatment, if there is clinical improvement, an oral antibiotic should be considered.
When the pathogen is known or suspected to be Pseudomonas, a suitable beta-lactam drug is often prescribed in combination with an aminoglycoside. A single agent cannot be relied upon for treatment of Pseudomonas. When the patient has renal insufficiency, azactam should be considered in place of the aminoglycoside.
In treatment of children with antibiotic suspensions, caregivers should be instructed in use of oral syringes or measuring teaspoons. Household teaspoons are not standardized and will give unreliable doses.
Resources
Periodicals
Moellering, R. C., Jr. "Linezolid." Summaries for Patients. Annals of Internal Medicine 138 (January 21, 2003): I-44.
Other
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