Prior antimicrobial therapy duration influences causative pathogens identification in ventilator-associated pneumonia

•Proportion of multidrug-resistant pathogens depends on the timing of prior antimicrobial treatment•Current but not recent antibiotic use is associated with a lower rate of positive culture with a higher proportion of MDR pathogens, mostly MDR Pseudomonas aeruginosa.•Further studies should investigate the usefulness of periodic assessment of lung microbiota.