Impact of an Acinetobacter baumannii outbreak on kidney events in a burn unit: A targeted machine learning analysis

Background Multidrug-resistant (MDR) bacteria outbreaksrepresent a major threat in intensive care units. Patients may then be exposed to drug-related direct toxicity during such outbreaks. The objective of this study was to explore the impact of an outbreakof imipenem-resistant Acinetobacter baumannii(IR-AB) on renal outcomes. Methods We performed a before-and-after observational study in a French burn intensive care unit during an IR-AB outbreak: a 13-month period before (period A, October 2013-October 2014) and a 13-month period after outbreakcontrol (period B, December 2014-December 2015). A total of 409 patients were included, 195 during period A and 214 during period B. The main endpoint was major adverse kidney events at day 90 (MAKE 90). Secondary endpoints were acute kidney injury (AKI) and persistent renal dysfunction. Results Incidence of MAKE 90 was 15.9% during period A versus 11.2% during period B ( P  = .166) and AKI 28.2% versus 18.7% ( P  = .023). The use of colistinwas associated with renal outcomes in univariate analysis. After adjustment of potential confounding factors using a targeted Machine Learning Analysis (ie, IR-AB-related infection, septic shock, severity scores, other nephrotoxics, chronic kidney disease, serum creatinine at admission, Staphylococcus aureus ), colistinremained associated with the risk of MAKE and AKI (relative risk = 2.909, 95% confidence interval [CI] [1.364, 6.204], P  = .006 for MAKE 90, and relative risk = 2.14, 95% CI [1.52, 3.02], P Conclusions The episode of IR-AB outbreakwas associated with an increased risk of kidney events, which appears to be driven by the use of colistin.