Investigation and Control of an Outbreak of Imipenem-resistant Acinetobacter baumannii Infection in a Pediatric Intensive Care Unit

BACKGROUND:This study investigated the clinical details and epidemiology of the imipenem-resistant Acinetobacter baumannii (IRAB) outbreak that occurred at a pediatric intensive care unit (PICU), and describes successful outcome of the implemented infection control measures. METHODS:With the recognition of 3 clustered cases with IRAB bacteremia at the PICU of Seoul National University Children’s Hospital, Korea, from August to September 2010, the following outbreak control strategies were implementedreinforcement of hand hygiene and contact precautions, investigation of environmental contamination, disinfection of the contaminated environment and medical equipment, active surveillance culture upon PICU admission and isolation of IRAB-positive patients. The clinical and microbiological data were reviewed for A. baumannii positive cases in the PICU from April 2001 to June 2011. Multilocus sequence typing was also performed. RESULTS:Twenty IRAB-positive cases (bacteremia in 10, pneumonia in 3 and colonizers in 7) were detected from January 2010 to February 2011. Thirteen IRAB-infected patients were all placed on a mechanical ventilator, had central venous catheters, received broad-spectrum antimicrobial treatment and had underlying diseases. Eleven (85%) IRAB-infected patients died probably due to IRAB infection. IRAB grew in 4 samples obtained from sinks and water taps from 38 environmental samples. Multilocus sequence typing analysis revealed 2 sequence typesST138 (n = 16) and its single-locus variant ST92 (n = 4). Eleven weeks after the initiation of active surveillance, no further IRAB isolates were identified. CONCLUSIONS:This study identifies the environmental source of an IRAB outbreak in a PICU and describes successful control of the outbreak with a multicomponent intervention program.