Abstract

To evaluate if risk factors for ventilation associated-pneumonia (VAP) by Pseudomonas aeruginosa differed among patients affected by P. aeruginosa producing metallo-β-lactamase (MBL-PA) or non-MBL-PA isolates. A 1-year retrospective case-control study was conducted in a surgical-clinical intensive care unit at a tertiary-care university hospital. Cases were patients with MBL-PA VAP and controls were those with non-MBL-PA VAP. Univariate and multivariate analysis were performed to identify risk factors. A total of 40 cases and 53 controls were included in the study. Univariate analysis showed that  a high-risk ASIS score, clinical category in hospital admission, prior hospitalization, length of ICU stay, length of mechanical ventilation, exposure to three or more antibiotics, exposure to carbapenems and fluoroquinolones were risk factors for VAP by MBL-PA. After logistic regression, the prior hospitalization and length of mechanical ventilation continued significant. The mortality was also independently associated with MBL-PA VAP. Hospitalization within the preceding year and length of mechanical ventilation were risk factors for MBL-PA VAP, deserving attention and further investigations.  MBL-PA VAP resulted in higher mortality rates most likely related to the commitment effective treatments of nosocomial infections by this organism. Early identification of patients with risk factors which could guide this initial appropriate empirical therapy and the development of strategies to prevent the dissemination of MBL-PA strains.

Key words: Metallo-β-lactamases, risk factors, P. aeruginosa, bacterial drug resistance, case-control studies.