Risk Factors and Impact on Clinical Outcome of Multidrug-Resistant Acinetobacter Baumannii Acquisition in Cardiac Surgery Patients.

Objectives: Acinetobacter baumannii recently has emerged as an important nosocomial pathogen. The aim of this study was to assess the impact on mortality of multidrug-resistant A. baumannii (MDR-AB) infection/colonization in patients undergoing cardiac surgery and to investigate microbiologic characteristics, epidemiologic spread of this pathogen, and the relative containment measures.

Design: Single-center, retrospective cohort study of prospectively collected data.

Setting: Cardiac surgery tertiary-care center.

Participants: Patients with positive MDR-AB cultures from September 1, 2009 to December 31, 2011.

Interventions: Bivariate and multivariate analyses were performed to individualize the risk factors for MDR-AB-infections in cardiac surgery patients. To evaluate the MDR-AB attributable mortality, a retrospective matched cohort study was performed. Incidence density ratio (IDR) was calculated to compare the MDR-AB infection/colonization before and after the introduction of preventive measures adopted following the first cases.

Measurements And Main Results: MDR-AB acquisition occurred in 14 patients (0,6%) of 2385 patients. At the multivariate analyses, preoperative use of inotropic drugs (OR 18.2, 95% CI 4.6-71.9) and logistic EuroSCORE (OR 1.09, 95% CI 1.06-1.13) were found as independent risk factors. Patients with MDR-AB had 57% cumulative in-hospital mortality; no statistical differences in mortality were observed in the matched group. IDR revealed a significantly decreased incidence of infection/colonization (0.3 per 1,000 days of stay compared with 0.03/1,000 days of stay, p = 0.0001) after the containment measures became effective.

Conclusions: Sicker patients are more susceptible to be infected by A. baumannii, but mortality is not significantly higher compared with other patients with similar characteristics. Adequate measures are fundamental to control the spread of the infection.