A Retrospective Closed Cohort Study on Distribution of Multidrug-Resistant Bacteria in Ventilator-Associated Pneumonia and its Impact on Patient Outcome

Objectives: Ventilator-associated pneumonia (VAP) is a common and serious nosocomial infection affecting critically ill patients undergoing mechanical ventilation. This study investigated the prevalence of multidrug-resistant (MDR) organisms in VAP, the VAP rate, and the outcomes associated with MDR-VAP. Methods: This retrospective single-center study, conducted in 2022, included adult ICU cases from April 2021 to March 2022, receiving mechanical ventilation for more than 48 h. Patient data were analyzed for demographics, comorbidities, empirical antibiotic use, and outcomes. MDR organisms were identified in respiratory cultures. Results: Among 447 patients, 133 developed VAP, with 96 cases being MDR-VAP. The mean age of the overall VAP population was 52 years, 70% of which were males. The incidence of VAP was 30.0% (95% CI: 25.7%-34.5%), while that of MDR-VAP was 21.6% (95% CI: 17.9%-25.8%). The most prevalent MDR organisms were Acinetobacter species (50%) and Klebsiella pneumoniae (46.9%). Empirical antibiotics were administered in 96% of VAP cases. The overall VAP rate was 38.03/1000 ventilator days. No single antimicrobial agent seemed to offer an empirical cover, as the susceptibility rate for most tested antimicrobials was less than 85%. Patients with MDR-VAP had a low survival rate (64.6%) and were less likely to be extubated at 13.5% compared to non-MDR-VAP (survival rate of 62.2%). COVID-19 patients had a high incidence of MDR VAP, especially with Acinetobacter. Overall, VAP mortality was 57.1%. The median ventilator days were 16 for VAP and only four for non-VAP. Conclusion: Gram-negative organisms, particularly Klebsiella and Acinetobacter, were the main MDR VAP culprits. MDR-VAP exhibited higher morbidity and mortality. A study focused on developing resistance by microorganisms is warranted for further understanding.