A growing body of research finds that telling patients to finish a full course of antibiotics even if they’re already feeling better not only fails to prevent drug-resistant “superbugs” from forming, but also might make those pathogens stronger.

The latest evidence comes from a study published this week in the journal BMJ by a group of British scientists. That team joins an expanding chorus of experts who said there’s no scientific support for the conventional wisdom, first adopted in the mid-1940s, that long courses of antibiotics help prevent bacteria from developing immunity to many or most of the weapons in the antibiotic arsenal.

In reality, these researchers said, the longer antibiotics are used, the more collateral damage is done to the body’s community of helpful bacteria — and that in turn gives resistant strains of bacteria, always present in the human body in small numbers, room to flourish and share their defenses with other pathogens, gradually leading to the superbug strains now estimated to kill 23,000 Americans per year and sicken more than 2 million.

Though the BMJ report is getting a lot of attention, other researchers in past years had also raised questions about the full-course antibiotic mantra.


One of them was Dr. Brad Spellberg, currently chief medical officer at the LAC+USC Medical Center and associate dean for clinical affairs at the Keck School of Medicine at the University of Southern California. Last year, he published a piece in the journal JAMA Internal Medicine that arrived at the same conclusions as the BMJ group’s findings.

Spellberg said Dr. Louis Rice, a specialist in infectious diseases who’s now at Brown University in Rhode Island, nearly a decade ago began bringing up the belief that completing full antibiotic courses may actually help build resistance in bacteria.

“We’ve been saying this for a long time. The message we are shifting to is that we need to be using short-course antibiotic regimens,” Spellberg said.

Today the standard practice is to prescribe courses of antibiotics for one or two weeks. Spellberg argues in his 2016 study that this approach has occurred for no other reason than that humans have thought in week-long blocks of time ever since the Roman Emperor Constantine the Great established the seven-day week in AD 321.


“Had Constantine decided there should be four days in a week, we would be prescribing antibiotics for four or eight days instead of seven or 14,” Spellberg said.

He said many of USC’s hospital programs and clinics are moving toward shorter-duration antibiotic prescriptions based on the latest evidence, but that many other medical organizations still insist on one- and two-week courses.

Dr. Julie Roth, chair of the family medicine department for Sharp Rees-Stealy Medical Group in San Diego, said while she and others at the organization may prescribe antibiotics for periods as short as one day, patients should not take articles like the one in BMJ as indications that they should stop their regimen when they think they’re feeling better.

“Some patients are sent home from the hospital on oral or (intravenous) antibiotics and need to work closely with their physician. They should not stop antibiotics unless they are directed to,” Roth said.


Andrei Osterman, a professor of bioinformatics who studies the specific mechanisms of bacterial resistance at the Sanford Burnham Prebys Medical Discovery Institute in La Jolla, said he agrees that administering antibiotics for longer than necessary does, indeed, cause collateral damage to the body’s microbiome — which can provide a home for drug-resistant bacteria to grow.

But he also noted that most antibiotics are only effective against bacteria that are actively multiplying, so the number of days in an antibiotic course needs to be long enough to catch those cells that were not yet dividing when the first few doses were administered.

“The primary driver of the number of days was not only preventing resistance, but also making sure there is enough exposure to make sure the infection is held at bay long enough for the body’s immune system to take over and finish the job,” Osterman said.

Human metabolic systems, he added, are highly variable in terms of how they process antibiotics, so a short course may work better for some people than others, depending on each patient’s specific genetics.


As is the case for the British researchers, Osterman said he believes more in-depth research is needed to understand just how long antibiotic courses should last. He said until those analyses are completed, caution is always the best idea, especially when the consequences could be death.

But Spellberg, the USC medical director, said the evidence really is there for anyone who chooses to look.

Multiple rigorous studies have shown that, for example, a five-day course is very effective in treating community-acquired pneumonia, a three-day regimen is adequate for simple bladder infections, five to seven days for kidney infections and four days for standard inter-abdominal infections such as appendicitis. While his organization and others in the Los Angeles area are increasingly prescribing shorter antibiotic courses, he insists they’re not neglecting their patients’ safety.

“Nobody’s talking about throwing their patients out the window. We’re talking about having an informed discussion between the provider and the patient about when the evidence shows it may be appropriate to stop a course of antibiotics ,” Spellberg said.


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paul.sisson@sduniontribune.com

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