Ventilator-associated pneumonia caused by multidrug-resistant organisms or Pseudomonas aeruginosa: Prevalence, incidence, risk factors, and outcomes

PurposeThe aim of this study was to clarify the prevalence and incidence of, risk factors for, and outcomes from suspected ventilator-associated pneumonia (VAP) associated with the isolation of either Pseudomonas or multidrug-resistant (MDR) bacteria (“high risk” pathogens) from respiratory secretions.Materials and MethodsData were collected as part of a large, multicentered trial of diagnostic and therapeutic strategies for patients (n = 739) with suspected VAP.ResultsAt enrollment, 6.4% of patients had Pseudomonas species, and 5.1% of patients had at least 1 MDR organism isolated from respiratory secretions. Over the study period, the incidence of Pseudomonas and MDR organisms was 13.4% and 9.2%, respectively. Independent risk factors for the presence of these pathogens at enrollment were duration of hospital stay ≥48 hours before intensive care unit (ICU) admission (odds ratio, 2.37 [95% CI, 1.40-4.02]; P = .001] and prolonged duration of ICU stay before enrollment (odds ratio, 1.50 [95% CI, 1.17-1.93]; P = .002] per week. Fewer patients whose specimens grew either Pseudomonas or MDR organisms received appropriate empirical antibiotic therapy compared to those without these pathogens (68.5% vs 93.9%, P < .001). The isolation of high risk pathogens from respiratory secretions was associated with higher 28-day (relative risk, 1.59 [95% CI, 1.07-2.37]; P = .04] and hospital mortality (relative risk, 1.48 [95% CI, 1.05-2.07]; P = .05), and longer median duration of mechanical ventilation (12.6 vs 8.7 days, P = .05), ICU length of stay (16.2 vs 12.0 days, P = .05), and hospital length of stay (55.0 vs 41.8 days, P = .05).ConclusionsIn this patient population, the incidence of high-risk organisms newly acquired during an ICU stay is low. However, the presence of high risk pathogens is associated with worse clinical outcomes.