Clonal spread of carbapenem-resistant OXA-23-positive Acinetobacter baumannii in a Bulgarian university hospital

ABSTRACTFrom October 1999 to September 2006, 29 carbapenem-resistant isolates of Acinetobacter baumannii were collected consecutively from patients hospitalized in different wards of the University Hospital in Pleven, Bulgaria. The blaOXA-23 gene, associated with the upstream-located ISAba1, was identified as the mechanism responsible for carbapenem resistance in all isolates. The isolates belonged to two different clonal groups, indicating a sustained hospital outbreak. This study demonstrates both the epidemic potential of carbapenem-resistant A. baumannii and its longevity in the hospital environment.