engleski

Extended-spectrum-β-lactamases-producing Stenotrophomonas maltophilia in the coastal marine environment

Stenotrophomonas maltophilia is an emerging multidrug resistant global opportunistic pathogen. The treatment of nosocomial infections by S. maltophilia is difficult, as this pathogen shows high levels of intrinsic or acquired resistance. The aim of this study was to investigate the antibiotic susceptibility profiles and the presence of extended-spectrum- β-lactamases (ESBLs) in S. maltophilia isolates from the marine waters at five sites along the coastal areas of the Split, Croatia. Sampling was performed in the period between May and October 2008 and between June 2009 and June 2010. The isolates were identified biochemically and then tested for susceptibility to 12 antimicrobial agents by disk diffusion method and Etest. Molecular characterization of ESBLs was performed by PCR with primers specific for TEM, SHV and CTX-M β- lactamases. Genetic relatedness of ESBL- producing isolates was determined by random amplified polymorphic DNA (RAPD) analysis. Out of 102 S. maltophilia isolates recovered, 87 (85.2%) were resistant to five or more drugs and demonstrated multiresistance phenotype with highest rates of resistance to ampicillin (100%) meropenem (92.5%) imipenem (92.5%) piperacilline (81.4%), tetracycline (81.4%), ceftazidime (48.1%) cefotaxime (25.9 %). Moreover, these isolates were also resistant to tobramicin, gentamicin, ciprofloxacin and trimethoprim-sulfamethoxazole. Among those 71 cephalosporin-resistant S. maltophilia, 19 (26.2 %) displayed an ESBL phenotype as evidenced by double-disk synergy test. Seventeen isolates (16.6 %) ESBL producing S. maltophilia isolates were identified by PCR. The blaCTX-M gene was present in 14 of 17 ESBL- producing isolates, with all belonging to CTX- M-1 group genes. The blaTEM gene was detected in 3 isolates and confirmed as blaTEM-116 by sequence analysis. No clonal relatedness was found between S. maltophilia isolates of marine water. This study illustrated that multidrug resistant bacteria and their resistance genes are widely distributed in coastal water and they pose a risk for transmitting these bacteria directly to humans through recreation or consummation seafood.

Stenotrophomonas maltophilia; extended-spectrum-β-lactamases (ESBLs); coastal water

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