Risk factors for relapse of ventilator-associated pneumonia related to nonfermenting Gram negative bacilli: a case-control study.

BACKGROUND: The aim of this study was to determine risk factors for relapse of ventilator-associated pneumonia (VAP) related to nonfermenting Gram negative bacilli (NF-GNB).

METHODS: This is a retrospective case-control study based on prospectively collected data. Two hundred and seventy six patients with monobacterial VAP related to NF-GNB were eligible. Patients with subsequent superinfection or persistent pulmonary infection were excluded. Patients with relapse of NF-GNB VAP were matched (1:2) with patients without relapse. Matching criteria included the duration of mechanical ventilation before VAP relapse, age+/-5 years, SAPS II at ICU admission+/-5, and the date of admission. Univariate and multivariate analyses were used to determine risk factors for relapse of NF-GNB VAP in cases and controls.

RESULTS: Thirty (10%) patients developed a relapse of NF-GNB VAP, 27 (90%) patients were successfully matched with 54 controls. Inappropriate initial antibiotic treatment was the only variable independently associated with relapse of VAP related to NF-GNB (OR [95% CI]=8.1 [2-33], p=0.003). Although ICU-mortality rate was similar in cases and controls (55% vs 72%, p=0.132), the duration of mechanical ventilation and ICU stay were significantly higher in cases than in controls.

CONCLUSION: Inappropriate initial antibiotic treatment is independently associated with relapse of VAP related to NF-GNB.