Abstract

The protective effects of commensal, anaerobic,gut microbiota have been established in various acute diseases [1–3]. This raises the question whether antibiotics depleting these anaerobic bacteria come with unexpected side-effects. We, therefore, read with great interest the article by Chanderraj et al. [4], which identified associations between treatment with anti-anaerobic antibiotics and adverse clinical outcomes in 3032 mechanically ventilated patients. By characterising gut microbiota in 116 patients and through animal experiments, the authors found evidence of causal effects of anti-anaerobic antibiotics on infectious and non-infectious outcomes. These findings demonstrate the harmful effects of anaerobic microbiota depletion in intensive care unit (ICU) patients.