Division of Comparative Medicine, Massachusetts Institute of Technology, Building 16-825, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA.
Vet Microbiol. 2020 Jan;240:108506. doi: 10.1016/j.vetmic.2019.108506. Epub 2019 Nov 15.
Escherichia coli encoding colibactin (clb), cytolethal distending toxin (cdt), and hemolysin-associated cytotoxic necrotizing factor (cnf) are associated with various intestinal and extra-intestinal diseases in humans and animals. Small mammal pets are not evaluated for genotoxin-encoding E. coli. Thus, the prevalence of such strains is unknown. The objective of this study was to isolate and characterize genotoxin-encoding E. coli from healthy and ill small mammal pets examined at a veterinary clinic and at two animal adoption centers. E. coli isolates were cultured from fecal samples and biochemically characterized. A total of 65 animals, including mice, rats, rabbits, guinea pigs, and hedgehogs, were screened. Twenty-six E. coli isolates were obtained from 24 animals. Twelve of the 26 isolates (46.2 %) were PCR-positive for the pks genes clbA and clbQ. Two isolates (7.7 %) were PCR-positive for cnf. All isolates were PCR-negative for cdt. All genotoxin-encoding isolates belonged to the pathogen-associated phylogenetic group B2. Representative genotoxin-encoding isolates had serotypes previously associated with clinical disease in humans and animals. Isolates encoding pks or cnf induced megalocytosis and cytotoxicity to HeLa cells in vitro. Although most isolates were obtained from healthy pets, two guinea pigs with diarrhea had pks-positive isolates cultured from their feces. Whole genome sequencing on four representative isolates confirmed the presence of pks and cnf genes and identified other virulence factors associated with pathogenicity in animals and humans. Our results suggest that small mammalian pets may serve as a reservoir for potentially pathogenic E. coli and implicate a zoonotic risk.
产 colibactin（clb）、细胞毒性扩张毒素（cdt）和溶血素相关细胞毒性坏死因子（cnf）的大肠杆菌与人类和动物的各种肠道和肠道外疾病有关。小型哺乳动物宠物不进行编码基因毒素的大肠杆菌检测。因此，这些菌株的流行情况尚不清楚。本研究的目的是从兽医诊所和两个动物收养中心检查的健康和患病的小型哺乳动物宠物中分离和鉴定编码基因毒素的大肠杆菌。从粪便样本中培养大肠杆菌分离株并进行生化特征分析。共筛选了 65 只动物，包括小鼠、大鼠、兔子、豚鼠和刺猬。从 24 只动物中获得了 26 株大肠杆菌分离株。26 株分离株中有 12 株（46.2%）PCR 阳性，可扩增出 pks 基因 clbA 和 clbQ。2 株分离株（7.7%）PCR 阳性，可扩增出 cnf。所有分离株均 PCR 阴性，无法扩增出 cdt。所有编码基因毒素的分离株均属于与疾病相关的 B2 型进化群。具有代表性的编码基因毒素的分离株具有以前与人类和动物临床疾病相关的血清型。体外实验中，编码 pks 或 cnf 的分离株诱导了 HeLa 细胞的巨细胞形成和细胞毒性。尽管大多数分离株来自健康的宠物，但两只患有腹泻的豚鼠粪便中培养出了 pks 阳性的分离株。对 4 株代表性分离株的全基因组测序证实了 pks 和 cnf 基因的存在，并鉴定出了其他与动物和人类致病性相关的毒力因子。我们的研究结果表明，小型哺乳动物宠物可能是潜在致病性大肠杆菌的储存库，并提示存在人畜共患病的风险。
