Stromberg Zachary R, Johnson James R, Fairbrother John M, Kilbourne Jacquelyn, Van Goor Angelica, Curtiss Roy, Mellata Melha
Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa, United States of America.
Veterans Affairs Medical Center and University of Minnesota, Minneapolis, Minnesota, United States of America.
PLoS One. 2017 Jul 3;12(7):e0180599. doi: 10.1371/journal.pone.0180599. eCollection 2017.
Extraintestinal pathogenic Escherichia coli (ExPEC) strains are important pathogens that cause diverse diseases in humans and poultry. Some E. coli isolates from chicken feces contain ExPEC-associated virulence genes, so appear potentially pathogenic; they conceivably could be transmitted to humans through handling and/or consumption of contaminated meat. However, the actual extraintestinal virulence potential of chicken-source fecal E. coli is poorly understood. Here, we assessed whether fecal E. coli isolates from healthy production chickens could cause diseases in a chicken model of avian colibacillosis and three rodent models of ExPEC-associated human infections. From 304 E. coli isolates from chicken fecal samples, 175 E. coli isolates were screened by PCR for virulence genes associated with human-source ExPEC or avian pathogenic E. coli (APEC), an ExPEC subset that causes extraintestinal infections in poultry. Selected isolates genetically identified as ExPEC and non-ExPEC isolates were assessed in vitro for virulence-associated phenotypes, and in vivo for disease-causing ability in animal models of colibacillosis, sepsis, meningitis, and urinary tract infection. Among the study isolates, 13% (40/304) were identified as ExPEC; the majority of these were classified as APEC and uropathogenic E. coli, but none as neonatal meningitis E. coli. Multiple chicken-source fecal ExPEC isolates resembled avian and human clinical ExPEC isolates in causing one or more ExPEC-associated illnesses in experimental animal infection models. Additionally, some isolates that were classified as non-ExPEC were able to cause ExPEC-associated illnesses in animal models, and thus future studies are needed to elucidate their mechanisms of virulence. These findings show that E. coli isolates from chicken feces contain ExPEC-associated genes, exhibit ExPEC-associated in vitro phenotypes, and can cause ExPEC-associated infections in animal models, and thus may pose a health threat to poultry and consumers.
肠外致病性大肠杆菌（ExPEC）菌株是导致人类和家禽多种疾病的重要病原体。一些从鸡粪便中分离出的大肠杆菌菌株含有与ExPEC相关的毒力基因，因此看起来具有潜在致病性；它们很可能会通过处理和/或食用受污染的肉类传播给人类。然而，鸡源粪便大肠杆菌的实际肠外毒力潜力却知之甚少。在此，我们评估了从健康生产鸡粪便中分离出的大肠杆菌菌株是否能在禽大肠杆菌病鸡模型以及三种与ExPEC相关的人类感染啮齿动物模型中引发疾病。从304份鸡粪便样本中分离出的大肠杆菌菌株中，通过PCR筛选了175株大肠杆菌菌株，以检测与人源ExPEC或禽致病性大肠杆菌（APEC，一种在禽类中引起肠外感染的ExPEC亚群）相关的毒力基因。对基因鉴定为ExPEC和非ExPEC的选定菌株进行体外毒力相关表型评估，并在大肠杆菌病、败血症、脑膜炎和尿路感染动物模型中进行体内致病能力评估。在研究的分离菌株中，13%（40/304）被鉴定为ExPEC；其中大多数被归类为APEC和尿路致病性大肠杆菌，但没有一株被归类为新生儿脑膜炎大肠杆菌。多个鸡源粪便ExPEC分离株在实验动物感染模型中引发一种或多种与ExPEC相关的疾病，这与禽类和人类临床ExPEC分离株相似。此外，一些被归类为非ExPEC的分离株能够在动物模型中引发与ExPEC相关的疾病，因此未来需要开展研究以阐明其毒力机制。这些发现表明，鸡粪便中的大肠杆菌分离株含有与ExPEC相关的基因，表现出与ExPEC相关的体外表型，并且能够在动物模型中引起与ExPEC相关的感染，因此可能对家禽和消费者构成健康威胁。
