Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Rd, Taipei, 10617, Taiwan.
Sustainable Swine Research Center, National Pingtung University of Science and Technology, Pingtung, Taiwan.
BMC Vet Res. 2024 Oct 21;20(1):480. doi: 10.1186/s12917-024-04317-z.
Porcine pathogenic Escherichia coli (E. coli), the globally recognized important pathogen, causes significant economic loss in the field. Enterotoxigenic E. coli (ETEC) causes porcine neonatal and post-weaning diarrhea (PWD), frequently carrying F4 adhesin, F18 adhesin, Heat-Stable toxin (ST), and Heat-Labile toxin (LT). Shiga Toxin-Producing E. coli (STEC) produces F18 adhesin and Shiga toxin type 2e (stx2e), majorly leading to systemic endothelial cell damage and edema disease. In this study, hemolytic pathogenic hybrid STEC/ETEC strains carrying ST and LT genes of ETEC and the Stx2e gene of STEC isolated from pigs with PWD in Taiwan were identified. The pathogenicity of a Taiwan hybrid STEC/ETEC strain was evaluated by oral inoculation in post-weaning pigs.
Next generation sequencing and multilocus sequence typing of two hybrid Taiwan porcine STEC/ETEC isolates indicated that these two isolates were closely related to the ST88 porcine hybrid STEC/ETEC isolated from pigs with watery diarrhea. Furthermore, the two hybrid Taiwan porcine STEC/ETEC isolates also displayed combinations of multiple resistance genes encoding mechanisms for target modification and antibiotic inactivation. Animal experiments confirmed that the Taiwan hybrid STEC/ETEC could cause watery diarrhea in post-weaning pigs with no signs of edema disease and minimal histopathological lesions.
To the best of the authors' knowledge, the present study is the first study demonstrating intestinal pathogenicity of the hybrid STEC/ETEC in pigs. The result suggests that the hybrid STEC/ETEC should be considered as a new emerging pathogen and a new target for vaccine development.
猪源致病性大肠杆菌（E. coli）是全球公认的重要病原体，在该领域造成了巨大的经济损失。肠致病性大肠杆菌（ETEC）引起仔猪和断奶后腹泻（PWD），常携带 F4 黏附素、F18 黏附素、耐热毒素（ST）和不耐热毒素（LT）。产志贺毒素大肠杆菌（STEC）产生 F18 黏附素和志贺毒素 2e（stx2e），主要导致全身内皮细胞损伤和水肿病。本研究从台湾 PWD 猪中分离到携带 ETEC 的 ST 和 LT 基因以及 STEC 的 Stx2e 基因的溶血性致病杂交 STEC/ETEC 菌株。通过对断奶后仔猪进行口服接种，评估了一株台湾杂交 STEC/ETEC 菌株的致病性。
对两株杂交台湾猪源 STEC/ETEC 分离株进行下一代测序和多位点序列分型表明，这两株分离株与从患有水样腹泻的猪中分离到的 ST88 猪源杂交 STEC/ETEC 密切相关。此外，这两株杂交台湾猪源 STEC/ETEC 分离株还显示出多种耐药基因的组合，这些基因编码了靶修饰和抗生素失活的机制。动物实验证实，台湾杂交 STEC/ETEC 可引起断奶后仔猪发生水样腹泻，但无水肿病迹象，组织病理学病变最小。
据作者所知，本研究首次证明了杂交 STEC/ETEC 在猪中的肠道致病性。结果表明，杂交 STEC/ETEC 应被视为一种新出现的病原体和疫苗开发的新靶标。
