Colistin Alone or with Meropenem: Is More Better?

Infection with extensively drug-resistant (XDR) gram-negative pathogens is associated with high mortality from both the infection and host comorbidities. Such infections have traditionally been treated with colistin/polymyxin therapy, with some evidence pointing to benefit of adding a carbapenem. Kaye and colleagues performed an international clinical trial from October 2012 to August 2020 to address whether colistin plus a carbapenem offers benefit over colistin monotherapy. Patients with pneumonia or bloodstream infection (BSI) caused by XDR Acinetobacter baumannii, XDR Pseudomonas aeruginosa, or carbapenem-resistant Enterobacterales were randomized to receive colistin (5 mg/kg once, followed by 1.67 mg/kg hourly) with placebo or with mer…