Investigation of a nosocomial outbreak of Acinetobacter baumannii producing PER-1 extended-spectrum β-lactamase in an intensive care unit

We investigated an outbreak of Acinetobacter baumannii in an adult intensive care unit of Kosin University Gospel Hospital in Busan, Republic of Korea. The outbreak involved 10 cases of infection by A. baumannii producing PER-1 extended -spectrum beta-actamase over a seven-month period, and was caused by a single pulsed-field get electrophoresis clone. The epidemic isolates were characterized by slight synergy between clavulanic acid and cefepime. Isoelectric focusing of crude bacteria[ extracts detected two nitrocefin-positive bands with pi values of 8.0 and 5.3. Polymerase chain reaction amplification and characterization of the amplicons by restriction analysis and direct sequencing indicated that the epidemic isolates carried a bla(PER-1) determinant. The epidemic isolates were characterized by a multidrug-resistant phenotype that remained unchanged over the outbreak, including penicillins, beta-lactam/ P-lactamase inhibitor, extended -spectrum cephalosporins and monobactams. Isolation of infected patients and appropriate carbapenem therapy were successful in ending the outbreak. Our report indicates that the blaPER-1 resistance determinant may become an emerging therapeutic problem. (C) 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.