Thread by @baym

Since it's World Antibiotic Awareness Week, let's revisit the recent article in which Llewelyn et al. convincingly argue that it's time to drop the message that not finishing a course of antibiotics contributes to resistance. Because it's incorrect

#WAAW
bmj.com/content/358/bm…

I once tried to track down the origins of this idea. I found dozens of papers claiming it, citing others, which cited others, and every chain went back to one source: Fleming's conjecture at his Nobel speech. Neither theory nor evidence support it.

From my reading of the sources, much of the original idea was the correct idea that marginally lethal doses of antibiotic could promote resistance (which is certainly true) but that this got conflated with the length of course at a fixed high dose, which is different

One thing that gets confused a lot in the literature on it is patient disease outcome vs antibiotic resistance. There are cases in which longer courses often do give better patient outcomes, but this is not the same as preventing resistance.

We certainly should not give antibiotics when they aren't needed. But we need to seriously question when that includes the latter part of a patient's course of antibiotics.

You wouldn't give abx to a healthy patient, why give them to a patient after the infection is cleared?

(Oh and the above article is behind a paywall, if that's an obstacle for you I strongly encourage searching for other sources that might let you read it anyway. It's worth it)

If we're serious about controlling antibiotic resistance (and we should be), we need evidence on what does and does not make resistance worse, not 75-year-old conjecture. Because only when we know what practices, if any, make a difference, can we change our ways for the better

This is the deeper question all of this raises: if not finishing antibiotic courses isn't meaningfully contributing to resistance, then what other assumptions about the drivers of resistance are we getting wrong? What human behaviors make a difference? Or even, do any?

Since it’s Twitter I want to be very clear I am not saying “ignore your doctor’s advice and freelance antibiotics.” That’s a terrible idea. I’m saying we, as a medical and scientific community, need to reassess guidance and tailor it based on evidence over tradition.