INTRODUCTION: Acinetobacter baumannii is a gram negative coccobacillus, opportunistic bacteria with low virulence. In recent years, it has become responsible for the increased incidence of infections in intensive care units (ICU), which are characterized by multi-resistance to broad-spectrum antibiotics. METHODS: Matched Case-Control Study, 1:4 ratio, in three cohorts of Acinetobacter baumannii outbreaks, from 2006 to 2010, at one university hospital. Odds Ratio was calculated with a confidence level of 95%, using conditional logistic regression. RESULTS: There were identified 3 outbreaks in the period 2006-2010, obtaining a sample of 14 cases and 56 controls. In multivariate analysis, statistically significant association was found between infection/colonization by A.baumannii and presenting a state of immunosuppression (OR = 15.45, 95% CI = 1.12-212.44) and having a central venous catheter for more than ten days (OR = 13.74, 95%CI=1.25-151.44). No statistically significant association was found between infection/colonization and mortality. In 14 cases, 13 had multi-resistant isolates, 9 were of respiratory origin, 2 blood cultures and 3 of abdominal origin. Mortality in cases was not associated with immunosuppression processes, bacteremia and infections /respiratory colonization. CONCLUSIONS: The infection/colonization by A.baumannii were associated with pacient immunosuppression status and having a central venous catheter for more than 10 days, which correlates with the invasive procedure, common in intensive care units. We were unable to clearly differentiate between infection and colonization, and its association with mortality.
