Genomic traits of multidrug resistant enterotoxigenic Escherichia coli isolates from diarrheic pigs

Jiameng Hu; Junlin Li; Xiaobo Huang; Jing Xia; Min Cui; Yong Huang; Yiping Wen; Yue Xie; Qin Zhao; Sanjie Cao; Likou Zou; Xinfeng Han

doi:10.3389/fmicb.2023.1244026

Genomic traits of multidrug resistant enterotoxigenic Escherichia coli isolates from diarrheic pigs

Front Microbiol. 2023 Aug 3:14:1244026. doi: 10.3389/fmicb.2023.1244026. eCollection 2023.

Authors

Jiameng Hu¹, Junlin Li¹, Xiaobo Huang^{1

2

3}, Jing Xia^{1

2

3}, Min Cui^{1

2

3}, Yong Huang^{1

2

3}, Yiping Wen^{1

2

3}, Yue Xie^{1

2

3}, Qin Zhao^{1

2

3}, Sanjie Cao^{1

2

3}, Likou Zou⁴, Xinfeng Han^{1

2

3}

Affiliations

¹ College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.
² Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of China, Chengdu, China.
³ Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.
⁴ College of Resources, Sichuan Agricultural University, Chengdu, China.

Abstract

Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) infections poses a significant challenge in global pig farming. To address this issue, the study was conducted to identify and characterize 19 ETEC isolates from fecal samples of diarrheic pigs sourced from large-scale farms in Sichuan Province, China. Whole-genome sequencing and bioinformatic analysis were utilized for identification and characterization. The isolates exhibited substantial resistance to cefotaxime, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, ampicillin, tetracycline, florfenicol, and sulfadiazine, but were highly susceptible to amikacin, imipenem, and cefoxitin. Genetic diversity among the isolates was observed, with serotypes O22:H10, O163orOX21:H4, and O105:H8 being dominant. Further analysis revealed 53 resistance genes and 13 categories of 195 virulence factors. Of concern was the presence of tet(X4) in some isolates, indicating potential public health risks. The ETEC isolates demonstrated the ability to produce either heat-stable enterotoxin (ST) alone or both heat-labile enterotoxin (LT) and ST simultaneously, involving various virulence genes. Notably, STa were linked to human disease. Additionally, the presence of 4 hybrid ETEC/STEC isolates harboring Shiga-like toxin-related virulence factors, namely stx2a, stx2b, and stx2e-ONT-2771, was identified. IncF plasmids carrying multiple antimicrobial resistance genes were prevalent, and a hybrid ETEC/STEC plasmid was detected, highlighting the role of plasmids in hybrid pathotype emergence. These findings emphasized the multidrug resistance and pathogenicity of porcine-origin ETEC strains and the potential risk of epidemics through horizontal transmission of drug resistance, which is crucial for effective control strategies and interventions to mitigate the impact on animal and human health.

Keywords: Enterotoxigenic Escherichia coli; antimicrobial resistance; genomic characterization; pig; virulence factor; whole-genome sequencing.