Objectives: The aim of this study was to identify and characterise probable extended-spectrum β-lactamase (ESBL)-, AmpC lactamase- and/or metallo-β-lactamase (MBL)-producing Escherichia coli variants circulating in the livestock and poultry environment to establish their epidemiological significance, genetic diversity, antimicrobial resistance (AMR) trends and virulence.
Methods: The culture method and E. coli-specific multiplex PCR identified 78 E. coli strains from faecal samples of healthy livestock and poultry. The antibiogram was determined by the disk diffusion and minimum inhibitory concentration (MIC) methods. Antimicrobial-resistant E. coli isolates were screened for the presence of ESBL, AmpC and MBL genes. Isolates were further characterised by plasmid replicon typing, integron assay and virulence gene analysis. Genetic diversity was assessed by random amplification of polymorphic DNA (RAPD) analysis and multilocus sequence typing (MLST).
Results: ESBL (CTX-M group 1, CTX-M group 4, TEM), AmpC (EBC, FOX, CMY, DHA) and MBL (IMP, SIM) resistance determinants were identified in 75%, 19% and 6% of isolates, respectively. Nine plasmid replicon types were distributed among resistant E. coli strains, with the most common plasmid replicon types being L/M and Y. Integrons were detected in 19% of E. coli isolates. RAPD analysis categorised the E. coli isolates into three clusters. MLST revealed seven different sequence types (STs), with ST10 being the most common.
Conclusions: This study demonstrated a high prevalence of animals carrying potential ESBL- and AmpC-producing E. coli and emphasises the need for rigorous surveillance in the animal sector to identify critical control points conducive to prevent the rapid dissemination of AMR.
Keywords: AmpC β-lactamase; Antimicrobial resistance; Escherichia coli; Extended-spectrum β-lactamase; India; Metallo-β-lactamase.
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