One of my standard sermons in this column is the danger of overusing antibiotics for mild infections that don’t need them, because then the bacteria (germs) become resistant to the antibiotics and, when you get a really serious infection, the antibiotics don’t work any more.
I suspect that most physicians believe a couple of things about this risk of developing resistance. First, the real problem is the long-term use of antibiotics. A few days’ worth is probably no big deal. Second, if you did develop resistance after just a few days of antibiotics, it is unlikely that the resistance would last for long, anyway.
That these beliefs are overly optimistic was shown by a recent study in the British medical journal The Lancet, conducted by a team of physicians and scientists from Belgium and the Netherlands.
They took about 200 healthy volunteers and gave a third of them each a short course of one of two antibiotics, while the remaining third were given a placebo. The antibiotics were azithromycin (brand name, Zithromax) for three days, or clarithromycin (Biaxin) for seven days. Both antibiotics are in what’s technically called the macrolide family.
The volunteers, before taking any antibiotics, had about 30 percent of the strep bacteria in their throats resistant to macrolides. The group receiving the placebo stayed at 30 percent, while the group given either antibiotic quickly shot up to around 80 percent macrolide resistance. The proportion of resistant bacteria did come down, but not quickly. It was still in the 60 to 70 percent range after six weeks and, even after six months, it remained significantly increased.
Now, there are a number of reasons why I might not have told you about a research study like this. It was done on healthy volunteers in a laboratory setting, not on sick people in hospitals or clinics. So you could quibble how much this actually has to do with medical practice or with patients’ health.
The European authors reply that, when you measure antibiotic resistance in the real world, you often have a hard time figuring out what caused what. Maybe antibiotics prescribing was the culprit, but maybe the germs became resistant in some other way completely.
The value of their study, they claim, is that they were able to show a direct causal link between the drugs and the resistance.
And, in the process, they showed that the resistance happened faster and lasted longer than most docs would have guessed.
So next time you think you need an antibiotic, and your physician offers you reasons why not, don’t get angry. She could be doing you, and all the rest of us, a big favor.
Dr. Howard Brody, a family physician, is director of the Institute for Medical Humanities at the University of Texas Medical Branch.
