Risk factors and attributable mortality of carbapenem-resistant acinetobacter baumannii infections

Background: The incidence density, the risk factors and the attributable mortality of carbapenem-resistant Acinetobacter baumannii (CR-AB) infections are rarely investigated. Aim: The aim of the present study was to determine the risk factors for CR-AB infection and to investigate whether CR-AB infection significantly increases the 28-day ICU mortality rate. Methods: A matched case-control study was conducted at the Medical/Surgical intensive care unit (ICU) of “SOTIRIA” general hospital in Athens, Greece from January 2009 to March 2010. Out of 156 ICU-admitted patients, 50 case-control pairs were selected. Cases were patients who acquired microbiologically documented CR-AB infection, while control patients without A. baumannii infection and were matched to the cases on APACHE II score, age, and length of ICU stay. Results: The incidence density of CR-AB infections was 16.8 /1000 ICU days. Multivariate conditional logistic regression analysis showed that the previous exposure to more than three different antibiotic classes was the only independent risk factor for the development of CR-AB (OR=34.0, 95% CI=2.22-522, P=0.01). The 28-day ICU mortality rates for cases and controls were 54% and 52%, respectively. Thus, the crude attributable mortality for CR-AB infections was 0.02 (95% CI=-0.18-0.22, P=0.84). Multivariate logistic regression analysis showed that CR-AB infection was not an independent predictor for 28-day ICU mortality rate (OR=1.40, 95% CI=0.46-4.22,P=0.55). Conclusions: Previous exposure to more than three different antibiotic classes was independently and significantly associated with the development of CR-AB. CR-AB infection was not associated with 28-day ICU mortality.

Author(s): Apostolopoulou Eleni

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