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J Antimicrob Chemother. 2011 Dec;66(12):2784-90. doi: 10.1093/jac/dkr363. Epub 2011 Sep 27.

CTX-M-15-producing Escherichia coli clone B2-O25b-ST131 and Klebsiella spp. isolates in municipal wastewater treatment plant effluents.

Author information

1
Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic. m.dolejska@centrum.cz

Abstract

OBJECTIVES:

The global occurrence of antibiotic resistance genes in bacteria in water environments is an increasing concern. Treated wastewater was sampled daily over a 45 day period from the outflow of a municipal wastewater treatment plant in Brno, Czech Republic, and examined for extended-spectrum β-lactamase (ESBL)-producing bacteria.

METHODS:

Water samples were cultivated on MacConkey agar with cefotaxime (2 mg/L) and individual colonies were examined for ESBL production. Phenotypic ESBL-positive bacteria identified as Escherichia coli or Klebsiella spp. were tested for the presence of antibiotic resistance genes, the virulence gene afa/dra and the bla(CTX-M) upstream region. Genetic relatedness was analysed by PFGE, multilocus sequence typing and plasmid analysis.

RESULTS:

A total of 68 ESBL-producing Enterobacteriaceae isolates were detected in 34 out of 45 wastewater samples. ESBL-producing isolates included 26 E. coli isolates, 4 Klebsiella pneumoniae isolates and 1 Klebsiella oxytoca isolate. The pandemic and multiresistant B2-O25b-ST131 clone was predominant, being detected among 19 E. coli isolates, and 17 of the B2-O25b-ST131 isolates were positive for the FIA replicon and the afa/dra operon and had an IS26 element flanking bla(CTX-M-15). Seventeen of the B2-O25b-ST131 isolates showed closely related PFGE profiles (defined by 84% band similarity) and belonged to identical clonal groups.

CONCLUSIONS:

The results highlight the inadequacy of the treatment process in removing multiresistant bacteria from municipal wastewater and point to a risk of transmission of clinically important multiresistant strains, such as the pandemic ST131 clone, to the environment. This is the first study demonstrating the pandemic ST131 clone in wastewater.

PMID:
21954457
DOI:
10.1093/jac/dkr363
[Indexed for MEDLINE]

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