β-lactam and fluoroquinolone resistance in Enterobacteriaceae from imported and locally-produced chicken in Mozambique

Abstract

Introduction: Plasmid-mediated resistance to β-lactam and fluoroquinolone antibiotics was investigated in Enterobacteriaceae isolated from retailed frozen chickens from Brazil, South Africa and Mozambique.

Methodology: Carcass swabs and the liquid thaw of 33 chickens from each of the three countries constituted the total sample size of 198. Isolates were identified by biochemical tests, antibiotic susceptibility was ascertained by the disc diffusion assay and β-lactamases were detected using the double-disk synergy test. PCR was used to detect the presence of blaCTX-M, blaSHV, blaTEM, blaCMY, blaMOX, blaFOX, blaDHA, qnrB, qnrD, qnrS and qepA genes. A random selection of CTX-M genes was sequenced.

Results: The 198 samples yielded 27 (13.6%) putative extended-spectrum β-lactamase (ESBL)-positive isolates, 15 from carcass swabs and 12 from the liquid thaw from 22 chickens with 19, 5 and 3 isolates from South African, Mozambican and Brazilian chicken, respectively. Isolates exhibited the following resistance: ampicillin 100%, ceftriaxone 89%, trimethoprim-sulfamethoxazole 78%, cefotaxime 74%, ciprofloxacin 70%, ceftazidime 67%, cefoxitin 22% and gentamicin 8%. The predominant putative ESBL gene was blaSHV (85%), followed by blaCTX-M (62.9%) and blaTEM (44.4%) whilst blaMOX and blaDHA were the most common pAmpC genes at 33.3%. The predominant plasmid-mediated fluoroquinolone-resistance gene was qepA (22.2%). DNA sequencing identified blaCTX-M-55/-79/-101/-164. ERIC-PCR profiles did not show strong evidence of clonality.

Conclusion: The Mozambican population is exposed to a reservoir of plasmid-mediated, and hence mobile β-lactam and quinolone resistance genes via imported, and to a lesser extent, locally produced poultry. This presents a food safety concern.

Keywords: CTX-M; ESBL; Enterobacteriaceae; antibiotic resistance; chicken; pAmpC.