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Taking full course of antibiotics is not always necessary — and may sometimes be harmful, say experts

REUTERS/Lucy Nicholson
Researchers say that taking antibiotics for longer than necessary increases the risk of antibiotic-resistance.

When we’re prescribed antibiotics for an infection, we’re almost always told by our doctor to “complete the course”— that is, to take all the pills, even after we feel better.

That instruction comes with a stern warning: Stopping treatment early might promote the growth of antibiotic-resistant bacteria.

Such advice is deeply ingrained in medical policy and practice. But is it correct?

Not according to a British team of microbiologists and infectious disease experts. In a commentary published Wednesday in the BMJ, they argue that the complete-the-course” message for antibiotics is not backed by the evidence and should be dropped.

In fact, the researchers, led by Martin Llewelyn of Brighton and Sussex Medical School, say that taking the drugs for longer than necessary increases the risk of antibiotic-resistance.

The rise of such resistance has become one of the most urgent global threats to human health — “the health crisis of our generation.” 

Currently, more than 2 million people in the United States become ill with antibiotic-resistant infections each year, according to the Centers for Disease Control and Prevention (CDC). And at least 23,000 Americans die each year as a direct result of the infections. 

Those numbers are expected to increase significantly in the coming years.

Where the idea started

The origins of the complete-the-course message regarding antibiotics “can be traced back to the dawn of the antibiotic era,” when the first patient was treated with penicillin, write the authors of the new commentary. They explain:

When [Australian pharmacologist] Howard Florey’s team treated [British police constable] Albert Alexander’s staphylococcal sepsis with penicillin in 1941 they eked out all the penicillin they had (around 4 [grams], less than one day’s worth with modern dosing) over four days by repeatedly recovering the drug from his urine. When the drug ran out, the clinical improvement they had noted reversed and he subsequently succumbed to his infection.

There was no evidence that this was because of resistance, but the experience may have planted the idea that prolonged therapy was needed to avoid treatment failure.

Indeed, in his acceptance speech for the 1945 Nobel Prize in Physiology or Medicine (which he shared with Florey), the Scottish biologist and discoverer of penicillin, Alexander Fleming warned, “If you use penicillin, use enough!” 

But that idea is outdated, say Llewelyn and his colleagues in the BMJ commentary. They describe growing evidence that has shown that shorter courses of antibiotics may be just as effective for treating many infections.

One course does not fit all

The researchers also make clear that there are some important exceptions — when a patient has a compromised immune system, for example, or if the bacterium behind the infection is a type that is slow growing or that lies dormant for long periods, as is the case with tuberculosis.

Some hospitals now test individual patients daily to determine when to stop antibiotic treatment. Although repeated testing would not be economically feasible outside of the hospital setting, primary care doctors — who write 85 percent of antibiotic prescriptions — could advise patients to stop taking the antibiotics when they feel better, the commentary authors propose.

Such action is needed, they say, because evidence is also building that the longstanding complete-the-course antibiotic message is contributing to drug-resistance bacteria.

“When a patient takes antibiotics for any reason, antibiotic sensitive species and strains among [microorganisms] on their skin or gut or in the environment are replaced by resistant species and strains ready to cause infection in the future,” the researchers explain. “This collateral selection is the predominant driver of the important forms of antibiotic resistance affecting patients today.”

“The longer the antibiotic exposure these opportunist bacteria are subjected to, the greater the pressure to select for antibiotic resistance,” they add. 

Needed: a tailored approach

Because “antibiotics are a precious and finite natural resource which should be conserved by tailoring treatment duration for individual patients,” the authors call at the end of their commentary for more clinical trials “to determine the most effective strategies for optimizing duration of antibiotic treatment.”

Michael Osterholm, director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota and co-author of the recently published book “Deadliest Enemy: Our War Against Killer Germs,” agrees. In an interview with MinnPost on Wednesday, Osterholm noted that the prescribing of antibiotics has been, at best, “a guestimate kind of treatment.”

Michael Osterholm
Michael Osterholm

“Today, as we recognize antibiotics for the very precious commodity that they are, we really need to go back and rethink what it means to be treated with antibiotics and how we can most effectively use them,” he said.

Overprescribing antibiotics to a patient raises concerns not only about antibiotic resistance, Osterholm explained, but also about disrupting the patient’s microbiome — the normal, healthy and protective organisms that live on and within each of us.

But Osterholm stresses that patients should not, on their own, alter the prescribed course of their antibiotics.

“We don’t want, in some instances, to cause patients to have a relapse in their infection,” he said. As the authors of the commentary also point out, the effects of antibiotics vary by pathogen, and some are much more likely to result in a relapse than others if the drugs are halted too soon.

“What this paper really calls for is a full-fledged effort in our research studies to understand when is it necessary to complete a certain course of antibiotics and when is it not — in fact, when it might even be advisable to do a short course,” Osterholm said.

So, continue to follow your doctor’s orders regarding antibiotics, but know that the idea that everyone needs to “complete the course” is just another in a long line of medical dogmas that is based on weak evidence and is likely to change.

“One of the beautiful aspects of science is the self-correcting theory of knowledge,” said Osterholm. “We always need to be asking, ‘What do we know?’ ‘How do we know it?’ and ‘Why do we know it?’”

FMI: You can read the full commentary online at the BMJ website.

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Comments (1)

  1. Submitted by Lawrence Lockman on 07/27/2017 - 12:02 pm.


    Many infections—for example due to viruses—are treated with antibiotics when they have no benefit. Some infections can be treated with narrow spectrum antibiotics rather than the broad spectrum drugs that are easier to prescribe but harder to think about. Both practices promote drug resistant bacteria.

    Most important, true strep throat SHOULD be treated with simple penicillin for the full 10 days, not to make the patient feel better but to prevent rheumatic fever, a late complication. I think the evidence for this recommendation, while old, was pretty solid.

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