Comparative genetic characterisation of third-generation cephalosporin-resistant Escherichia coli isolated from integrated and conventional pig farm in Korea

초록

Objectives: Pig-farming systems consist of integrated or conventional farms, and many antimicrobials are used to treat bacterial infections. The objective of this study was to compare characteristics of third generation cephalosporin resistance and extended-spectrum fi-lactamase (ESBL)/pAmpC fi-lactamase-producing Escherichia coli between integrated and conventional farms.Methods: Third-generation cephalosporin-resistant E. coli was collected from integrated and conventional pig farms from 2021 to 2022. Polymerase chain reaction and DNA sequencing were performed for the detection of fi-lactamase-encoding genes, molecular analysis, and identification of genetic relationships. To determine the transferability of fi-lactamase genes, conjugation assays were conducted.Results: Antimicrobial resistance rates were higher in conventional farms than in integrated farms; ESBLand pAmpC-lactamase-producing E. coli rates were higher in conventional farms (9.8%) than in integrated farms (3.4%). Fifty-two (6.5%) isolates produced ESBL/pAmpC fi-lactamase genes. Isolates from integrated farms harboured CTX-15 (3 isolates), CTX-55 (9 isolates), CTX-229 (1 isolate), or CMY-2 (1 isolate) genes; isolates from conventional farms harboured CTX-1 (1 isolate), CTX-14 (6 isolates), CTX-15 (2 isolates), CTX-27 (3 isolates), CTX-55 (14 isolates), CTX-229 (1 isolate), and CMY-2 (11 isolates) genes. Of the 52 ESBL/pAmpC fi-lactamase-producing E. coli isolates, class 1 integrons with 11 different gene cassette arrangements were detected in 39 (75.0%) isolates, and class 2 integrons were detected in 3 isolates. The most common sequence type in both integrated and conventional farms was ST5229, followed by ST101, and then ST10.Conclusion: Third-generation cephalosporin-resistant patterns and molecular characteristics differed between integrated and conventional farms. Our findings suggest that continuous monitoring of third generation cephalosporin resistance on pig farms is necessary to prevent the dissemination of resistant isolates.& COPY; 2023 The Authors. Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

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