Early Anti-Anaerobic Antibiotics May Worsen Outcomes in Critically Ill

TUESDAY, Oct. 18, 2022 (HealthDay News) -- Early administration of anti-anaerobic antibiotics is associated with an increased risk for mortality among critically ill patients, according to a study published online Oct. 13 in the European Respiratory Journal.

Rishi Chanderraj, M.D., from the University of Michigan Medical School in Ann Arbor, and colleagues examined the effects of anti-anaerobic antibiotics on the risk for adverse clinical outcomes in a retrospective single-center cohort study of 3,032 critically ill patients. Intensive care unit outcomes were compared in all patients, and changes in gut microbiota were compared in a subcohort of 116 patients.

The researchers found that early administration of anti-anaerobic antibiotics correlated with reductions in ventilator-associated pneumonia-free survival, infection-free survival, and overall survival (hazard ratios, 1.24, 1.22, and 1.14, respectively). Decreased initial gut bacterial density was seen in patients who received anti-anaerobic antibiotics, and they had increased microbiome expansion during hospitalization and domination by Enterobacteriaceae spp. In anti-anaerobic antibiotic-treated patients, Enterobacteriaceae were also enriched among respiratory pathogens. Treatment with anti-anaerobic antibiotics increased susceptibility to Enterobacteriaceae pneumonia in murine models and increased the lethality of hyperoxia.

"Both observational clinical data and animal modeling suggest that this mortality risk is not solely attributable to increased rates of infection. Further inquiry is needed to interrogate the mechanisms underlying this mortality risk," the authors write.

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