engleski

First report of TEM-52 beta-lactamase in Proteus mirabilis strains from Croatia

ABSTRACT Background and aim Recently an increased frequency of extended spectrum β -lactamase (ESBL) positive P. mirabilis isolates was observed in University Hospital Split. The aim of this study was the molecular characterization of ESBLs in P. mirabilis strains from University Hospital Split in Croatia. Material and methods Seven P. mirabilis strains with reduced susceptibility to ceftazidime were isolated from different clinical samples during 2007 and 2008 in University Hospital Split. Minimum inhibitory concentrations (MICs) of wide range of antibiotics were determined by a twofold microdilution technique according to CLSI. Conjugation experiments were set up employing E. coli A15 R- strain free of plasmids and resistant to rifampicin. The presence of blaESBL, genes was determined by polymerase chain reaction (PCR) with primers specific for TEM. SHV, CTX-M and PER-1 β -lactamases. Plasmids were extracted by alkaline lysis methods. Genotyping of P. mirabilis strains was performed by pulsed-field gel electrophoresis (PFGE). Results ESBLs were detected in all strains by double-disk synergy test and confirmed by at least eightfold reduction of ceftazidime MIC in the presence of clavulanate. All strains were resistant to amoxycillin, gentamicin and ciprofloxacin, but susceptible to combination of ceftazidime with clavulanic acid, piperacillin/tazobactam, aztreonam, cefoxitin, imipenem and meropenem. Cephalosporins showed variable degrees of resistance ; ceftazidime and ceftriaxone MICs varied between 8 and 256 mg/L, while cefotaxime MICs were slightly lower (8-128 mg/L). Cefepime showed better activity with MICs varying between 4 and 64 mg/L. According to the disk-diffusion test all strains were resistant to tetracycline, chloramphenicol and all except one to sulphametoxazole/trimethoprim. Three strains transferred resistance to E. coli recipient. The resistance to chloramphenicol, gentamicin and tetracycline was cotransferred alongside with ceftazidime resistance from two strains whereas sulphametoxazole/trimethoprim resistance was transferable from one strain. A plasmid of approximately 70 kb was isolated from three representative strains All seven strains yielded an amplicon of 853 bp with primers specific for TEM β -lactamases. Sequencing of blaTEM genes revealed TEM-52 β -lactamase. All strains have shown to possess identical PFGE patterns. Conclusions This is the first report of TEM-52 β -lactamase from Croatia. TEM-52 β -lactamase with similar properties was previously described in Salmonella enterica serovar enteritidis strains from Scotland, Hungary, Korea, France, Belgium and Greece and in P. mirabilis from Italy and France. The fact that the strains were clonally related and showed similar resistance phenotypes points out that there is endemic and epidemic spread of TEM-52 producing P. mirabilis causing nosocomial infections in University hospital Split. Key words: TEM-52 β -lactamase, Proteus mirabilis, extended spectrum β -lactamases

Proteus mirabilis; extended-spectrum beta-lactamases; TEM-52 beta-lactamase

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