Risk-Factors And Impact On Clinical Outcome Of Multidrug-Resistant Acinetobacter Baumannii Acquisition In Cardiac Surgery Patients

Objectives Acinetobacter baumannii has recently 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 microbiological characteristics, epidemiological spread of this pathogen and the relative containment measures. Design Single-center, retrospective cohort study of prospectively collected data Setting Cardiac surgery tertiary-care centre Participants Patients with Positive MDR-AB culture from 1st September 2009 to 31 December 2011. Interventions Bivariate and multivariate analyses were performed to individuate 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 analysis preoperative use of inotropic drugs (OR 18.2, 95%CI 4.6-71.9) and logistic Euroscore (OR1.09, 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 significant decreased incidence of infection/colonization (0.3 per 1000 days of stay compared with 0.03/1000 days of stay, p = 0.0001) after the containment measures became effective. Conclusions Sicker patients are more subjected 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.