Finish your antibiotics course? Maybe not.

One of the most well-known concepts in medicine, to both doctors and patients, is that you absolutely must finish a course of antibiotics. The thinking goes that if you don’t kill every last bacterium, those that survive can pick up resistance and wreak further havoc.

The concern was voiced by the venerated Alexander Fleming himself, discoverer of penicillin, the first true antibiotic--which is probably why the idea is so enduring. Toward the end of his 1945 Nobel Prize acceptance speech, Fleming warned that “there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to nonlethal quantities of the drug make them resistant.”

However, this is only half true. If we truly want to slow the spread of antibiotic resistance, we also need to look at antibiotics overprescription.

Recently, a group of UK health professionals penned a compelling analysis in The BMJ, formerly called The British Medical Journal, advocating for shorter antibiotics courses--even going so far as to say that maybe patients should stop taking antibiotics once they feel better.

That’s because Fleming only described one version of resistance, where bad bugs get badder by surviving an underdosing of antibiotics. Researchers call that “target selection”.

However, there’s a flip side: overusing antibiotics can cause usually nice bugs with which we coexist to gain resistance, jumping at the opportunity to take over ecological niches like the gut of a patient on antibiotics. This form of resistance is called “collateral selection”.

The different mechanisms by which bacteria acquire antibiotic resistance.

The different mechanisms by which bacteria acquire antibiotic resistance.

In their analysis, Dr. Martin Llewelyn and colleagues found that “most of the bacterial species now posing the greatest problems do not develop resistance through target selection,” and that “collateral selection is the predominant driver of the important forms of antibiotic resistance affecting patients today.”

So, overdosing antibiotics is a bigger threat than underdosing.

Yet many health practitioners and patients are so worried about breeding superbugs through underdosing that antibiotics courses are often unnecessarily long. The researchers’ analysis showed that shorter courses of several quinolone-class antibiotics are just as effective as the longer courses that are currently prescribed, but they also conceded that there’s just not enough scientists doing these studies. “No such data exist for β-lactams, which are the main antibiotic class used,” Llewelyn and colleagues wrote. “Current international guidelines recommend 10-14 days’ treatment with β-lactams, based purely on absence of data for shorter courses.”

So worried are most health professionals about underdosing that most antibiotics prescriptions for adults are not calibrated to account for differences in patients. For example, “under current practices, a 200 lb., 6’2″ man diagnosed with pneumonia would receive the same dose of antibiotics as a 124 lb., 5′ woman with the same condition, despite their dramatically different body sizes.”

Antibiotic resistance is a growing problem due to people overusing antibiotics at home--in hospitals, however, where the concentration of antibiotics and at-risk people is high, it’s already a grave concern. That’s why hospital staff around the world are on the front lines of developing more appropriate protocols for using antibiotics in a collective effort called “antimicrobial stewardship”.

In our recent reporting for the PBS NewsHour series “Stopping Superbugs”, Miles met some of these antimicrobial stewards at Tufts Medical Center in Boston, Massachusetts.

Dr. Shira Doron suits up to protect Tufts Medical Center from superbugs.

Dr. Shira Doron suits up to protect Tufts Medical Center from superbugs.

“We’re facing a crisis,” said Dr. Shira Doron, Physician Director of the Antimicrobial Stewardship Program at Tufts. “What we need to be doing is treating until the person feels better and then stopping.”

This approach is not without its risks, acknowledges Doron: “Some of those people may have a recurrence of infection. But the number of antibiotic days that you’re saving the general population if you take that approach is so large and the impact is so large that it needs to be sort of the next phase of medicine.”

But carefully managing antibiotics courses is a tough ask for already overworked doctors. A multitude of factors pressure doctors to overprescribe antibiotics, chimed in Doron’s colleague Dr. Helen Boucher.

“I think that especially in America, patients come in with an agenda,” Boucher said. “They expect an antibiotic. It takes longer to not give an antibiotic. We have shorter and shorter times per interaction with patients. When I started, it was 30 to 60 minutes, now it’s 15 to 30 minutes. It’s harder to have that conversation to explain that we’re going to do this test, see how you do, and then decide about an antibiotic and I’ll call you tomorrow. That’s a lot of work.”

Dr. Helen Boucher says patients should ask doctors for shorter courses of antibiotics.

Dr. Helen Boucher says patients should ask doctors for shorter courses of antibiotics.

Patients should take to heart the lessons learned by antimicrobial stewards in hospitals and do their own part in preventing the overuse of antibiotics.

“We’ve learned for a very few infections, ear infections in two-year-olds, you need to treat for the whole course. But for many others, we’re learning that shorter is fine,” said Boucher. “So, I think if you’re a patient at a doctor you should ask, ‘Do I need to take it all or not?’ And oftentimes, the answer will be, ‘No.’”