Analysis of antibiotic resistance phenotypes and genes of Escherichia coli from healthy swine in Guizhou, China.

Bo Yu,Jinge Xu,Shijin Bu,Yanan Zhang,Li Yang

doi:10.4102/ojvr.v88i1.1880

Abstract

This study was carried out to investigate the resistance phenotypes and resistance genes of Escherichia coli from swine in Guizhou, China. A total of 47 E. coli strains isolated between 2013 and 2018 were tested using the Kirby–Bauer (K–B) method to verify their resistance to 19 common clinical antimicrobials. Five classes consisting of 29 resistance genes were detected using polymerase chain reaction. The status regarding extended-spectrum β-lactamase (ESBL) and the relationship between ESBL CTX-M-type β-lactamase genes and plasmid-mediated quinolone resistance (PMQR) genes were analysed. A total of 46 strains (97.9%) were found to be multidrug resistant. Amongst them, 27 strains (57.4%) were resistant to more than eight antimicrobials, and the maximum number of resistant antimicrobial agents was 16. Twenty antibiotic resistance genes were detected, including six β-lactamase genes blaTEM (74.5%), blaCTX-M-9G (29.8%), blaDHA (17.0%), blaCTX-M-1G (10.6%), blaSHV (8.5%), blaOXA (2.1%), five aminoglycoside-modifying enzyme genes aac(3′)-IV (93.6%), aadA1 (78.7%), aadA2 (76.6%), aac(3′)-II c (55.3%), aac(6′)-Ib (2.1%) and five amphenicol resistance genes floR (70.2%), cmlA (53.2%), cat2 (10.6%), cat1 (6.4%), cmlB (2.1%), three PMQR genes qnrS (55.3%), oqxA (53.2%), qepA (27.7%) and polypeptide resistance gene mcr-1 (40.4%). The detection rate of ESBL-positive strains was 80.9% (38/47) and ESBL TEM-type was the most abundant ESBLs. The percentage of the PMQR gene in blaCTX-M-positive strains was high, and the detection rate of blaCTX-M-9G was the highest in CTX-M type. It is clear that multiple drug resistant E. coli is common in healthy swine in this study. Extended-spectrum β-lactamase is very abundant in the E. coli strains isolated from swine and most of them are multiple compound genotypes.

Highlights

Colibacillosis is a common infectious disease in swine caused by pathogenic Escherichia coli, and the main manifestations are sepsis, yellow scour and white scour in piglets
Antibiotic resistance genes (ARGs) carried by E. coli of food animal origin would spread along the food chain and eventually cause harm to the public and human health (Gao, Han & Guan 2017; Yin, Chen & Cao 2018)
This study investigated the prevalence of resistance phenotypes and resistance genes of E. coli isolated from swine in Guizhou in recent years, analysed ESBL status and the relationship between CTX-M-type β-lactamase genes and plasmid-mediated quinolone resistance (PMQR) genes

Summary

Introduction

Colibacillosis is a common infectious disease in swine caused by pathogenic Escherichia coli, and the main manifestations are sepsis, yellow scour and white scour in piglets. The infection caused by extended-spectrum β-lactamase (ESBL) producing bacteria increases the difficulty to control and represents a major global public health concern. CTX-M-15 (forming part of the CTX-M-1 subfamily first described in E. coli in 2001 from India [Karim et al 2001]) is the most frequent CTX-M worldwide. Antibiotic resistance genes (ARGs) carried by E. coli of food animal origin would spread along the food chain and eventually cause harm to the public and human health (Gao, Han & Guan 2017; Yin, Chen & Cao 2018). It is necessary to monitor the prevalence of drug resistance and ARGs in animals, in swine

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