Impact of the adequacy of antibiotic therapy on the outcome of ventilator-associated pneumonia

Introduction

The aim was to assess the impact of empiric antibiotic adequacy on ICU outcome of patients with ventilator-associated pneumonia (VAP), the reasons for inadequacy and risk factors for potential multidrug-resistant organisms.

Methods

During a 24-month period a multiple-centre observational study was conducted in five ICUs. Adult patients with documented VAP were segregated for analysis. Empiric antibiotic therapy was classified as adequate or inadequate according to in vitro efficacy against all isolated bacteria. The day of ICU discharge or death was recorded. Comparison between survivors and nonsurvivors was performed. Infection with potential multidrug-resistant organisms (methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumanii or Stenotrophomonas maltophilia) was evaluated for therapeutic inadequacy, ICU length of stay before diagnosis and previous use of antibiotics.

Results

One hundred and twenty-three patients with VAP (age 62.7 ± 16.9 years, 65.9% men, and SAPS II 49.5 ± 15.5) were identified. Empiric antibiotic therapy was adequate in 65.9%. These patients' ICU mortality was significantly lower in comparison with those with inadequate therapy (28.4% vs. 45.2%, P = 0.049). Patients infected with a potential multidrug-resistant organism were more likely to receive inadequate antibiotic therapy (80.1%, P = 0.001), and to have had longer previous ICU stay (11.5 days vs. 7.2 days, P = 0.005), but there was no difference in the previous use of antibiotics (65.2% vs. 50%, P = 0.102).

Conclusions

An empiric adequate antibiotic therapy was associated with a lower mortality rate in VAP. Multidrug-resistant organisms were significantly associated with therapeutic inadequacy and longer ICU length of stay.