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.