PURPOSE: Invasive carbapenem-resistant Acinetobacter baumannii (CRAB) infection is associated with high morbidity and mortality rates in critically ill patients and neonates. We aimed to determine the risk factors of invasive infection in neonates with CRAB colonization, and differences in clinical outcomes between CRAB colonization and infection groups during the CRAB outbreak. METHODS: We retrospectively collected data from 45 patients with CRAB during the outbreak at the Neonatal Intensive Care Unit of Seoul National University Children's Hospital from May 2011 until April 2012. RESULTS: CRAB infection developed in 7 neonates (15.5%). Clinically significant patent ductus arteriosus (colonization group, 57.9% vs. infection group, 100%; P=0.04) and intubation state at initial CRAB isolation (44.7% vs. 100%, respectively; P=0.01) were more prevalent in the infection group. Univariate analysis results showed that a 1-min Apgar score of < or =3 and a CRIB II score of >14 had odds ratios of 9.9 (P=0.04) and 24.0 (P=0.02), respectively, for invasive CRAB infection. Total lengths of intubation, central venous catheterization, and CRAB isolation were significantly longer in the invasive infection group than colonization group. As a clinical outcome, incidence of bacteremia other than CRAB (26.3% vs. 71.4%, P=0.03) was higher in the infection group, but there was no differences in the mortality rates between groups (15.8% vs. 42.9%, respectively; P=0.13). CONCLUSION: A 1-min Apgar score of < or =3, a CRIB II score of >14, clinically significant patent ductus arteriosus, and intubation state at initial isolation were found to be risk factors for invasive CRAB infection during the outbreak. During CRAB outbreak, early and appropriate antimicrobial treatment should be administered to high-risk patients.