Bacterial epidemiology and attributable mortality of Ventilator-associated pneumonia before and after COVID-19 pandemic (2018-2021)

Background Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in mechanically ventilated patients. The COVID-19 pandemic has profoundly modified VAP epidemiology and microbial ecology. Methods We conducted a prospective multicenter cohort study within the REA-REZO network (≈20% of French ICU beds), 1 January 2018–31 December 2021. All adults receiving invasive mechanical ventilation were included. VAP was defined according to ECDC criteria. Primary endpoints were VAP incidence density (per 1000 ventilation-days) and 30-day attributable mortality. Secondary endpoints included resistance patterns and pre-pandemic versus pandemic trends. Results Among 98,047 patients, 12,251 patients developed VAP, with an incidence of 18.9/1000 ventilation-days. Peak incidence occurred at day 10 (29/1000 ventilation-days). Thirty-day attributable mortality was 4.9% [95% CI 3.7;6.2], rising to 7.2% [6.0;8.5] at 60 days. Gram-negative bacteria accounted for 78.0% of isolates, predominantly Enterobacterales (46%) and Pseudomonas aeruginosa (20%). Third-generation cephalosporin resistance reached 27% in Enterobacterales and 25% in P. aeruginosa . The COVID-19 patients had a higher VAP rate (19.5% vs 9.7%, p<0.001) and mortality (36.9% vs 31.0%, p<0.001). Conclusions VAP remains highly prevalent in French ICUs with substantial attributable mortality. The COVID-19 pandemic nearly doubled VAP incidence and worsened resistance profiles. Intensified prevention bundles during the first 10 days of ventilation and reinforced antimicrobial stewardship are critical.