Impact of colonization with multidrug-resistant bacteria on the risk of ventilator-associated pneumonia in septic shock.

PURPOSE: The objective is to identify the risk markers of multi-drug resistant bacteria (MDRB) related ventilator-associated pneumonia (VAP) in septic shock patients with previous MDRB carriage. MATERIAL AND METHODS: This retrospective study was conducted in a medical ICU from 2010 to 2020. Consecutive patients with septic shock and still in the ICU after 48 h, were eligible. The following microorganisms were defined as MDRB: extended-spectrum beta-lactamase producing enterobacteriaceae, methicillin-resistant Staphylococcus aureus, multi-drug resistant Pseudomonas aeruginosa, imipenem-resistant Acinetobacter baumanii and Stenotrophomonas maltophilia. Screening for MDRB colonization was performed at ICU admission and during ICU stay. The determinants of MDRB-related VAP were assessed using a time-dependent cause-specific Cox model. RESULTS: 643 patients were analyzed and 122 (18.9%) had at least one episode of VAP. The overall ICU mortality was 32.5%. The incidence of MDRB carriage was 31%, distributed into MDRB carriage at admission (14.3%) and MDRB acquired during ICU stay (16.7%). In multivariate analysis, MDRB colonization in ICU was independently associated with an increased risk of VAP (CSH: 1.85; 95% CI: 1.05-3.23; p = 0.03) whereas carriage prior to admission was not. CONCLUSION: Imported and acquired MDRB carriage harbor different risks of subsequent MDRB-related VAP in patients with septic shock.