It’s not always a good idea to finish your prescription

Prescription drugs could be making harmless bacteria in the body resistant to antibiotics, which could then spread the resistance to more threatening bugs.

Contrary to conventional wisdom, it may not always be best to finish your prescriptions, according to British researchers.

Doctors have traditionally told their patients to “complete the course,” meaning that even if their symptoms have gone away, they should keep taking antibiotics until they finish their prescription. The thinking was, that a patient should keep taking the medication to ensure that all of the bacteria have been destroyed so that remaining bugs won’t become drug-resistant. It’s been fairly standard medical practice for decades. But some experts are starting to question it.

A new analysis published in BMJ found that there’s a risk that prescription drugs could make other bacteria in the body resistant, which could then spread the resistance to more threatening bugs.

“It is very unlikely that all bacterial of a particular species are killed, even after a prolonged course of treatment, unless the host immune system finishes them off. However, it is also likely that other bacteria, ‘colonizers’ in the body which are normally harmless will get resistance and then be able, in the future, to pass on the resistant genes to other more harmful bacteria,” said Oxford University disease and epidemiology expert, Tim Peto, who co-authored the study.

For example, Peto said, “patients who are prescribed repeated doses of antibiotics for recurrent urinary tract infections are more at risk of developing resistant bacteria.”

Prolonged antibiotic use doesn’t just affect the target bacteria, it affects the whole body and all the other, usually harmless, bacteria in it. Once the target bacteria is gone or, at least, no longer a problem, the continued antibiotic use changes all the other bacteria in the body. Prolonged use of antibiotics selects for the strongest strains of all that bodily bacteria. The study found some of that bacteria can come out of it resistant to antibiotics.

Down the road, that could turn into a problem for everyone.

The big resistance threats, the report noted, are Escherichia coli, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter app, Pseudomonas app, Enterobacter app and others. Normally, these live in our bodies without harming us, but they can also act as carriers for drug-resistant genes. That resistance can then swap between other strains or species of bacteria.

But “it is unclear whether the duration of each treatment course makes a difference,” Peto said.

Peto said patients obviously shouldn’t ignore their prescriptions, but insisted the whole process should be rethought so the dosage ends early if the problem is resolved.

“Our work is designed to facilitate a proper debate and further clinical research to obtain good evidence as to how to treat patients. In the short term, the clinician and patient together can probably easily work out a sensible treatment regimen which includes an early stop if the patient has a good response to treatment,” he said.

Doing that, the report said, should minimize bacterial exposure and adaptation to antibiotics.

This patient-centred approach can better adapt to the fact that some people recover from illnesses more quickly than others.

“Dr. Peto is absolutely correct that we need to continue to work hard at reducing the duration of antibiotic use” Dr. Allison McGeer, microbiologist at Mount Sinai hospital said, noting “the duration of antibiotics we use has decreased substantially in the last decade, as we have recognized the risk and worked hard at reducing duration.” However, McGeer said more research is needed and “it is difficult, expensive, and boring to do the studies that will demonstrate that five days of antibiotics are as good as seven or 10.”

Author: Mitchell Thompson

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Photo credit: Janice Carr / CDC

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