Characteristics of extended-spectrum β-lactamase (ESBL)- and pAmpC beta-lactamase-producing Enterobacteriaceae of water samples in Tunisia

Sci Total Environ. 2016 Apr 15:550:1103-1109. doi: 10.1016/j.scitotenv.2016.01.042. Epub 2016 Feb 9.

Abstract

The presence of extended-spectrum beta-lactamase and plasmid-mediated AmpC beta-lactamase producing Enterobacteriaceae (ESBL-Eb and pAmpC-Eb, respectively) was analyzed in 57 wastewater and 57 surface-water samples in Tunisia. Twenty-four of the 57 wastewater samples (42.1%) and one of the 57 surface-water samples (1.7%, a river that received effluents of a wastewater-treatment-plant) contained ESBL-Eb or pAmpC-Eb; one ESBL/pAmpC-Eb per positive sample was further characterized. Beta-lactamase genes detected were as follows: blaCTX-M-1 (10 Escherichia coli),blaCTX-M-15 (eight E. coli, one Klebsiella pneumoniae, one Citrobacter freundii), blaCTX-M-14 (one E. coli) and blaCMY-2 (four E. coli). The blaTEM-1, blaOXA-1 or blaSHV-1 genes were also found in 72% of these isolates. The ISEcp1, orf477 or IS903 sequences were found upstream or downstream of blaCTX-M genes. Class 1 integrons were present in 16 of the 25 ESBL-Eb/pAmpC-Eb strains (64%), and contained five different gene-cassette arrays. Most of the strains (76%) showed a multiresistant phenotype and qnr genes were identified in four strains. Molecular typing of ESBL/CMY-2-producing E. coli isolates showed 23 different PFGE-patterns and 15 different sequence-types (ST10, ST46, ST48, ST58, ST69, ST101, ST117, ST131, ST141, ST288, ST359, ST399, ST405, ST617, and the new ST4530); these strains were ascribed to phylogroups A (11 isolates), B1 (3 isolates), D (6 isolates) and B2 (3 isolates). From one to five plasmids were detected in each strain (size from 30kb to >240kb) and ESBL or pAmpC genes were transferred by conjugation in 69.5% of the E. coli strains. In conclusion, ESBL-Eb and pAmpC-Eb strains are frequently detected in wastewater samples and they might be a source for dissemination in other environments with repercussion in public health.

Keywords: CTX-M; ESBL; Tunisia; Wastewater; pAmpC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / analysis
  • Bacterial Proteins / metabolism*
  • Drug Resistance, Bacterial
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / growth & development*
  • Enterobacteriaceae / metabolism
  • Environmental Monitoring*
  • Genes, Bacterial
  • Tunisia
  • Water Microbiology*
  • Water Pollutants, Chemical / analysis*
  • beta-Lactamases / analysis
  • beta-Lactamases / metabolism*

Substances

  • Bacterial Proteins
  • Water Pollutants, Chemical
  • AmpC beta-lactamases
  • beta-Lactamases