Yet another reason to avoid unnecessary antibiotics

Z pack

The commonly prescribed medications azithromycin and levofloxacin are probably killing people. A recently study by Rao and colleagues in the Annals of Family Medicine had a pretty eye-popping result:

“Compared with amoxicillin, azithromycin resulted in a statistically significant increase in mortality and arrhythmia risks on days 1 to 5, but not 6 to 10. Levofloxacin, which was predominantly dispensed for a minimum of 10 days, resulted in an increased risk throughout the 10-day period.”

I have prescribed a fair amount of azithromycin and levofloxacin over the years, the former more than the latter. No more. The excess deaths appear to be due to cardiac causes.

Read the study here: Azithromycin and Levofloxacin Use and Increased Risk of Cardiac Arrhythmia and Death

Of course, Miriam Barlow showed us years ago that amoxicillin was preferable to other antibiotics (for an entirely different reason – avoiding antibiotic resistance). E. coli harbor a plasmid that can only accommodate one resistance allele at a time. The ancestral beta lactamase (blaTEM) that confers resistance to only to penicillin has a selective advantage over more recently evolved multi-drug resistant beta lactamases, especially when penicillin is given. As a result, a penicillin like amoxicillin selects for E. coli sensitivity to antibiotics in other classes. This is a largely unexplored avenue of preserving drug sensitivity. Perhaps there is a connection between these two findings (probably not!).

Either way, the Rao et al result will give more ammunition to physicians trying to talk their patients out of antibiotics for self-limiting conditions. If an antibiotic is absolutely necessary, perhaps the old standby amoxicillin will do.

Much credit is due to Yosuf Leibman of the EMU Monthly blog for alerting me to this study. The EMU Monthly is a highly, highly recommended site. Check it out.

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