Blog | Monday, May 20, 2013

Is your doctor relying on bad information?

When I was a medical student, my friends and I wore white coats so stuffed with reference books we could barely move. When we were taking care of patients, a trip to the library simply wasn't practical, and that whole internet thing wasn't really up and running yet. Now my pocket contains only my smart phone.

Sure, I know more than I did then, but I also know that I am fallible. I like to look things up, and from my phone I can access a world of medical information. Certain resources have become more popular than others, but there is no way to gauge the quality of these resources other than relying on my opinions and those of my colleagues. Online references are a tempting but risky resource for doctors.

Two of the more widely-used resources are UpToDate and eMedicine. UpToDate is just that: a resource of practical medical knowledge that is updated frequently by experts. It's also very expensive (about $500/year last time I checked). eMedicine from Medscape is free, and usually quite reliable. Last week, though, I stumbled upon a something disturbing.

Moraxella catarrhalis is a common bacterium causing disease in humans. It causes sinus infections, bronchitis, ear infections, especially in children, but in adults it can be quite deadly. It's a serious bug. Thankfully, it's usually pretty responsive to antibiotics. But here's were eMedicine loses me:

Numerous different antimicrobials have been employed to treat M catarrhalis infection (see below). In addition, among the medicinal plants, garlic, cinnamon, and avocado leaves have all been found to be antagonistic to M catarrhalis.

This makes it seem as if antibiotics and medicinal plants are on equal footing here: They are not. M. catarrhalis can cause serious, life-threatening illness. There is no reason to think that avocado, garlic, or any other plant can be used in place of or even as an adjunct to antibiotics.

Most doctors know this. Many patients who stumble upon this information may not, leading to delay of therapy. I'm going to be keeping an eye on Medscape products looking for similar problems, but the real lesson here is that even with the entirety of medical knowledge in the palm of your hand, the guidance of a professional is important in interpreting and using this knowledge.


A reader pointed me to the study that was likely the source of the claims about treating M. cat with avocado, etc. As expected, it is an in vitro look at the effect of these substances on the bacteria. In my into to microbiology course, we would often grow out cultures of various bacteria, setting, for example, a slice of garlic on the medium to see if it would inhibit growth (we also did much more sophisticated versions of this experiment. While interesting, these studies say nothing about the clinical utility of these substances. The human body is very different from a Petri dish. For these plants to be used as treatments, they would have to be "weaponized," creating a way to deliver useful doses of the plant without, for example, having the putative active ingredients destroyed in the acidic environment of the stomach.

When researching antibiotics, candidate substances are identified either by computer modeling or good old-fashioned trial and error in the lab. After that comes years of testing to see if there is a way to make it useful in human beings. The study authors' conclude that (emphasis mine): "Garlic, cinnamon and avocado leaves extracts represents alternative source of natural antimicrobial substances for use in clinical practice for the treatment of cases of M. cattarhalis."

This is irresponsible and just plain wrong. The study doesn't lead us to conclude anything about clinical practice and to claim otherwise is bad science and bad medicine.

Peter A. Lipson, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. After graduating from Rush Medical College in Chicago, he completed his internal medicine residency at Northwestern Memorial Hospital. This post first appeared at his blog at Forbes. His blog, which has been around in various forms since 2007, offers "musings on the intersection of science, medicine, and culture." His writing focuses on the difference between science-based medicine and "everything else," but also speaks to the day-to-day practice of medicine, fatherhood, and whatever else migrates from his head to his keyboard.