Genetic Features of the Widespread Plasmid Coding for the

Complete sequencing of plasmid pOXA-48a carrying the blaOXA-48 gene from a Klebsiella pneumoniae isolate was performed. Its backbone corresponded to that of an IncL/M-type plasmid, in which the blaOXA-48 gene had been integrated through the acquisi-tion of the Tn1999 composite transposon without any other antibiotic resistance gene. Molecular epidemiology using a collec-tion of international OXA-48 producers revealed the wide diffusion of pOXA-48a or closely related plasmids. Carbapenem-hydrolyzing -lactamases belonging to Amblerclasses A, B, and D have been found worldwide among the Enterobacteriaceae (24). Although carbapenem-hydrolyzing class D -lactamases (CHDLs) are identified mainly in Acinetobacter species (19, 23), OXA-48 has been identified only in the Entero-bacteriaceae. The blaOXA-48 gene was first identified in a Klebsiella pneumoniae isolate from Turkey (22). Since then, several other OXA-48-producing isolates of various enterobacterial species (in-cluding Citrobacter freundii and Escherichia coli) have been re