Antibiotics are important drugs, perhaps the most important. In a world beset with “an unprecedented wave of new and old infections,” as one expert recently wrote, it is critically important that antibiotics work well when people need them.
But antibiotics are frequently misused — overprescribed or incorrectly taken by patients, and recklessly fed to farm animals. As a result, lifesaving antibacterial drugs lose effectiveness faster than new ones are developed to replace them.
Each year, 100,000 people in the United States die from hospital-acquired infections that are resistant to antibiotics, according to the Infectious Diseases Society of America.
These concerns led Dr. Zelalem Temesgen, an infectious disease specialist at the Mayo Clinic in Rochester, Minn., to create a 15-part “Symposium on Antimicrobial Therapy,” published in February in The Mayo Clinic Proceedings. The series is intended in part to help practicing physicians know when and how antibiotics should be used — and, equally important, when they should not.
Improving how antibiotics are prescribed can do more than curb resistance. It can save lives and money by reducing adverse drug reactions and eliminating or shortening hospital stays, Dr. Temesgen said.
The first installment in the series, based on guidelines developed by the infectious diseases society and published with Dr. Temesgen’s introduction, was devoted to helping doctors practice better medicine. It also can help patients better understand how and when antibiotics work best, and it can arm them with the right questions when an antibiotic prescription is being considered.
Patient-Tailored Therapy
The report, prepared by three infectious disease specialists — Surbhi Leekha, now at the University of Maryland, and Drs. Christine L. Terrell and Randall S. Edson, both at the Mayo Clinic — urged doctors to avoid a “one size fits all” approach to antibiotics. Rather, they said, many individual factors must be taken into account to ensure the right drug and the right dose are prescribed for each patient.
It is often up to the patient to make sure the prescribing physician is aware of these influential factors. They include:
Kidney and liver function. The kidneys and liver eliminate drugs from the body. If the organs are not working well, toxic levels can accumulate in the bloodstream.
Age. Considering a new antibiotic? This is no time lie about your age. “Patients at both extremes of age handle drugs differently, primarily due to differences in body size and kidney function,” the experts wrote. A face-lift and hair coloring may disguise your geriatric status, but they will not help your kidneys process drugs as well as they did in your youth. In some cases, in young, otherwise healthy patients, higher drug doses may be needed to be sure that therapeutic levels are maintained.
Pregnancy and nursing. Some antibiotics given to a pregnant or lactating woman can adversely affect her baby, and it is critically important to tell the prescribing doctor if you are pregnant (or might be pregnant) or nursing. The risk of drug-induced birth defects is highest in the first three months of pregnancy; during the last three months, drugs are eliminated from the body more quickly, and higher doses may be needed to maintain a therapeutic blood level.
Drug allergy or intolerance. Make sure the doctor knows if you have ever had a bad reaction to an antibiotic. But — and this is important — neither you nor your doctor should assume you are allergic to, for example, penicillin because you once developed a rash while taking it. The rash could have been caused by the illness or something else entirely.
When an allergy is suspected, a skin test should be performed to confirm it so that the ideal antibiotic treatment is not mistakenly ruled out in the future.
“It has been shown that only 10 percent to 20 percent of patients reporting a history of penicillin allergy were truly allergic when assessed by skin testing,” the experts wrote.
In an interview, Dr. Edson said it is possible to rapidly desensitize a patient to a needed antibiotic by administering progressively larger oral doses of the drug.
Recent antibiotic use. Tell the doctor if you recently took an antibiotic. If you develop a bacterial illness within three months of antibiotic therapy, you may have a drug-resistant infection that requires use of an alternate class of medication.
Genetic characteristics. Some people are born with factors that make them especially vulnerable to bad reactions from certain antibiotics. For example, in those with a condition known as G6PD deficiency, which is most common among blacks, certain antibiotics can lead to the destruction of red blood cells. Patients who could be at risk should be tested for G6PD deficiency beforehand.
The Value of a Culture
When patients arrive at the doctor’s office with an inflamed throat, deep cough, high fever or unrelenting sinus pain, more often than not they are given prescriptions for antibiotics. The experts noted that it is sometimes reasonable to treat an infection without first getting a culture of the responsible organism — like when the patient’s symptoms are typical of a known bacterial infection.
“Doctors do have to exercise clinical judgment in many cases,” Dr. Edson said. For example, he and his co-authors wrote, “Cellulitis is most frequently assumed to be caused by streptococci or staphylococci, and antibacterial treatment can be administered in the absence of a positive culture.”
Likewise, they added, community-acquired pneumonia (that is, pneumonia that develops somewhere other than a hospital) can be treated with an antibiotic without patients first receiving a diagnostic test.
But all too often, the cause of a patient’s symptoms is not bacterial and may not even be an infection. In these cases, taking an antibiotic will do no good and may even be harmful. Possible nonbacterial causes include a viral infection (which will not respond to an antibiotic), a connective tissue disorder or an allergy, Dr. Edson said.
He and his co-authors emphasized the importance of getting a laboratory to identify the responsible organism when the likely cause of symptoms is not apparent or when patients have a serious or life-threatening infection, require long-term antibiotic therapy or fail to benefit from the drug chosen initially.
Sometimes a culture will indicate the need to administer two antibiotics simultaneously — for example, when the infectious organism produces an enzyme that inactivates what would otherwise be the most effective antibacterial drug.
The experts also urged that if patients were first treated with a broad-spectrum antibiotic (one that attacks a number of different bacteria), doctors should consider switching to a narrow-spectrum drug that targets the specific cause once it is identified through a laboratory culture. This could reduce the risk of other bacteria becoming resistant to the broad-spectrum drug.
