Researchers urge tracking anaerobic activity of antibiotics to protect microbiomes

Dr. Tessa Andermann, associate professor of infectious diseases at the University of North Carolina at Chapel Hill, urged antibiotic stewardship programs to consider anaerobic activity when choosing agents for vulnerable patients. "We tested this score in a burn ICU cohort, and we found that the highest AAI quartile demonstrated an association with increased 90-day infection or death versus the lowest AAI quartile," she said, describing how antibiotics with stronger anaerobic activity correlate with increased antimicrobial-resistance gene diversity and abundance in the gut.

Andermann recommended three concrete actions: (1) integrate anaerobic-activity metrics such as the AAI into stewardship tracking rather than relying solely on spectrum or duration, (2) make colonization (not only clinical infection) a surveillance endpoint, and (3) fund and prioritize development of microbiome-sparing therapeutics and repletion strategies. She noted randomized trials are difficult in very sick patients and that confounding by indication remains a challenge for observational studies of antibiotic impacts.