The impact of antimicrobial resistance and aging in VAP outcomes: experience from a large tertiary care center.

BACKGROUND: Ventilator associated pneumonia (VAP) is a serious infection among patients in the intensive care unit (ICU). METHODS: We reviewed the medical charts of all patients admitted to the adult intensive care units of the Massachusetts General Hospital that went on to develop VAP during a five year period. RESULTS: 200 patients were included in the study of which 50 (25%) were infected with a multidrug resistant pathogen. Increased age, dialysis and late onset (≥ 5 days from admission) VAP were associated with increased incidence of resistance. Multidrug resistant bacteria (MDRB) isolation was associated with a significant increase in median length of ICU stay (19 vs. 16 days, p=0.02) and prolonged duration of mechanical ventilation (18 vs. 14 days, p=0.03), but did not impact overall mortality (HR 1.12, 95% CI 0.51-2.46, p=0.77). However, age (HR 1.04 95% CI 1.01-1.07, p=0.003) was an independent risk factor for mortality and age ≥ 65 years was associated with increased incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections (OR 2.83, 95% CI 1.27-6.32, p=0.01). CONCLUSIONS: MDRB-related VAP is associated with prolonged ICU stay and mechanical ventilation. Interestingly, age ≥ 65 years is associated with MRSA VAP