Antibiotic use and resistance link demonstrated
A study demonstrating the direct link between antibiotic use and emergence of bacterial resistance has been published in The Lancet.
Belgian and Dutch researchers took pharyngeal swabs from 224 volunteers
before and after treatment with azithromycin (500mg once daily for three
days), clarithromycin (500mg twice daily for seven days) or placebo.
Over a period of 180 days, both antibiotics increased the proportion
of macrolide-resistant streptococci compared with placebo, peaking at
day 8 in the clarithromycin group and at day 4 in the azithromycin group.
The proportion of resistant strains was higher after azithromycin treatment
than after clarithromycin treatment. However, clarithromycin use was
associated with an increased chance of streptococci carrying the erm(B)
gene, which confers high-level macrolide resistance (2007;369:482).
The author of an accompanying comment piece (ibid, p442) warns that any
drive to reduce the use of macrolide antibiotics in the community and,
in turn, to reduce macrolide resistance will require more than a prescribing
campaign. “Indeed, if macrolide use was discouraged because of
concern over their resistance potential, patients might end up receiving
a drug that is more toxic, more expensive, and perhaps even better at
selecting for resistance.”
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