Objectives: The present study was designed to provide a snapshot on carbapenemase-producing Pseudomonas aeruginosa (n=11) and Acinetobacter baumannii (n=7) isolates in hospitalized patients (November 2011, January-March 2012) from two main hospitals in Bucharest, south Romania.
Methods: Clonality among isolates was established by PFGE, MLST and Fourier transform infrared spectroscopy. Carbapenemases were screened by the Blue-Carba test, PCR and sequencing. Transferability of blaOXA-23 was tested by conjugation and plasmid typing (number, size and identity) was assessed by S1-PFGE, replicon typing, hybridization and PCR mapping.
Results: All P. aeruginosa isolates carried chromosomally located blaVIM-2, associated with a common class 1 integron (aacA7-blaVIM-2) or an atypical configuration (aacA7-blaVIM-2-dfrB5-tniC). These isolates belonged to unusual lineages; mostly ST233 disseminated in one hospital unit, with ST364 and ST1074 also being detected. A. baumannii isolates carried blaOXA-23 in Tn2008, which was found truncating a TnaphA6 transposon located in a common 60 kb GR6 (aci6) pABKp1-like conjugative plasmid in highly related CC92 clones (ST437, ST764 and ST765), where CC stands for clonal complex.
Conclusions: Our results show the spread of VIM-2-producing P. aeruginosa and OXA-23-producing A. baumannii clinical isolates in two hospitals from Bucharest and highlight a peculiar population structure in this Eastern European country. Also, we demonstrate the dissemination of a common and conjugative aci6 pABKp1-like plasmid scaffold in different A. baumannii clones and we report the first known identification of Tnaph6-carrying pACICU2-like plasmids in Europe.
Keywords: OXA-23; ST233; ST437; Tn2008; TnaphA6; VIM-2; pACICU2 plasmid.
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