Evaluation of Escherichia coli isolates from healthy chickens to determine their potential risk to poultry and human health

Abstract

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.

A comparative phylotyping analysis of <i>E. coli</i> originating from avian colibacillosis based on the Clermont triplex scheme and <i>gyrA</i> gene sequencing

“…The discrepancy in the reported prevalence displays the heterogenicity of the APEC isolates. Various studies explained that some APEC strains may be a derivation of commensal isolates by acquisition of virulence genes through mobile genetic elements (29)(30)(31). In the present survey, segregation of E. coli isolates into six subgroups concurs with the results revealed by Ghanbarpour et al (15).…”

“…The most common APEC phylogroups reported from Mexico were B1 and B2 (both 34.7%) and A (8.6%) (29), versus the predominance of phylogroups A (73%) and D (14%) stated from the south of China (30). In another study, APEC isolates were concentrated in phylogroups A (63%), D (33%), and B2 (4%), with the lack of any isolate in phylogroup B1 (31). The discrepancy in the reported prevalence displays the heterogenicity of the APEC isolates.…”

Genomic analysis of avian-pathogenic Escherichia coli (APEC) isolated from diseased chicken

“…There is, however, a substantial overlap especially within the B2 phylogenetic group, which comprises strains isolated from both humans and chickens, showing high virulence in both chicken and mammalian models with low or no host specifity (18,19,17). Moreover, an isolate showing high virulence in rat meningitis model has been found in faeces of a healthy chicken (5), another finding implying a potential importance of poultry and poultry products as a source of human pathogens.…”

“…For a long time APEC strains were considered merely opportunistic pathogens, predominantly, but not exclusively associated with O1, O2, O8, O78 and several other serogroups (2). It has nevertheless been proved that diseaseassociated E. coli strains encode multiple putative virulence genes and significantly differ from commensals, particularly in the presence of ColV plasmid-associated genes, possible markers of poultry-adapted pathogenic strains (3)(4)(5).…”

Lethality Prediction for Escherichia Coli O157:H7 and Uropathogenic E. coli in Ground Chicken Treated with High Pressure Processing and Trans‐Cinnamaldehyde

“…ExPEC (UPEC), as well as other UC and UTI associated pathogens such as Klebsiella pneumoniae are associated with community‐based UTI outbreaks with clinical isolates being both similar and identical to food (poultry, meat, produce isolates) by phylogenetic group, antibiotic resistance, virulence factor profiles, pulsed‐field gel electophoresis type, and whole genome sequencing (Cortez et al., ; Davis et al., ; Jakobsen et al., ; Jakobsen et al., and ; Johnson et al., ; Lyhs et al., ; Vincent et al., ). ExPEC (UPEC) and other potentially uropathogenic bacteria isolated directly from food, including poultry, have been shown to cause UTI in animal model systems (Davis et al., ; Stromberg, Johnson, & Fairbrother, ; Vincent et al., ). However, the actual percentage of ExPEC‐related human infections/illnesses directly associated with foods is not clearly confirmed yet since multiple routes might occur in those cases (Nordstrom, Liu, & Price, ; Singer, ).…”