Comparison of Extraintestinal Pathogenic Escherichia coli Strains from Human and Avian Sources Reveals a Mixed Subset Representing Potential Zoonotic Pathogens

Abstract

Since extraintestinal pathogenic Escherichia coli (ExPEC) strains from human and avian hosts encounter similar challenges in establishing infection in extraintestinal locations, they may share similar contents of virulence genes and capacities to cause disease. In the present study, 1,074 ExPEC isolates were classified by phylogenetic group and possession of 67 other traits, including virulence-associated genes and plasmid replicon types. These ExPEC isolates included 452 avian pathogenic E. coli strains from avian colibacillosis, 91 neonatal meningitis E. coli (NMEC) strains causing human neonatal meningitis, and 531 uropathogenic E. coli strains from human urinary tract infections. Cluster analysis of the data revealed that most members of each subpathotype represent a genetically distinct group and have distinguishing characteristics. However, a genotyping cluster containing 108 ExPEC isolates was identified, heavily mixed with regard to subpathotype, in which there was substantial trait overlap. Many of the isolates within this cluster belonged to the O1, O2, or O18 serogroup. Also, 58% belonged to the ST95 multilocus sequence typing group, and over 90% of them were assigned to the B2 phylogenetic group typical of human ExPEC strains. This cluster contained strains with a high number of both chromosome-and plasmid-associated ExPEC genes. Further characterization of this ExPEC subset with zoonotic potential urges future studies exploring the potential for the transmission of certain ExPEC strains between humans and animals. Also, the widespread occurrence of plasmids among NMEC strains and members of the mixed cluster suggests that plasmid-mediated virulence in these pathotypes warrants further attention. Speculation has long existed regarding a food-borne origin for extraintestinal pathogenic Escherichia coli (ExPEC) strains (28,33,42) and has spawned recent work investigating E. coli contaminants of food and the ExPEC strains of food-producing animals (15,18,24,40). Of particular interest in this regard are avian pathogenic E. coli (APEC) strains that cause colibacillosis in poultry (3,9,35,36,38). Although it has been widely assumed that most APEC strains do not possess zoonotic potential, recent reports have suggested otherwise for certain groups of strains (2,9,29,30,35,36), and some researchers have demonstrated that APEC strains and their plasmids may be transmitted to human hosts (27,38). Recently, APEC isolates have been compared to ExPEC isolates from human urinary tract infections (UTIs) and neonatal meningitis, revealing that these "subpathotypes" have some overlap in serogroups, phylogenetic groups, virulence genotypes, and abilities to cause disease in certain animal models (9,30,31,35,36). The validity of these observations was sustained by comparison of the first APEC genome sequence with sequenced ExPEC isolates of humans (25), which revealed that few differences existed between the sequenced APEC strain (APEC O1) and human strains. In fact, results of an in silico multilocus sequence typing ...

Multi-locus sequence typing and plasmid profile characterization of avian pathogenicEscherichia coliassociated with increased mortality in free-range layer flocks

“…This particular plasmid replicon type has previously been associated with virulence in poultry (Johnson et al, 2007(Johnson et al, , 2008, and horizontal transfer of plasmids of this replicon type might represent a risk factor for changing a commensal E. coli into a more virulent form (Cusumano et al, 2010).…”

Recombinant Iss as a Potential Vaccine for Avian Colibacillosis

“…For instance, when Moulin-Schouler et al (33) compared O18:K1 ExPEC strains of human and avian origin for common virulence factors and genetic relationship, they found that APEC and NMEC share several virulence factors and overlap in their phylogenetic grouping. Also, in a study of over 1,000 ExPEC from human and avian sources, Johnson et al (24) found a mixed cluster of ExPEC subpathotypes (APEC, NMEC, and UPEC) that shared much overlap in their virulence genotypes and belonged to serogroups, MLST types, and phylogenetic groups that typify human pathogens. They regarded the isolates of this mixed cluster as being potential zoonotic pathogens.…”

“…E-mail: lknolan@iastate.edu AVIAN DISEASES 56:192-199, 2012 Key words: APEC, colibacillosis, ExPEC, immunization, Iss, vaccine Abbreviations: APEC 5 avian pathogenic Escherichia coli; ELISA 5 enzyme-linked immunosorbant assay; ExPEC 5 extraintestinal pathogenic E. coli; GST 5 glutathione-S-transferase; GST-Iss 5 glutathione-S-transferase-Iss (the fusion protein); HICS 5 hyperimmune chicken sera; IPTG 5 isopropyl-b-D-thiogalactopyranoside; NMEC 5 neonatal meningitis E. coli; PBS 5 phosphate-buffered saline; PBSt 5 phosphate-buffered saline with 0.05% TweenH 20; SPF 5 specific-pathogen-free; UPEC 5 uropathogenic E. coli Avian pathogenic Escherichia coli (APEC), the causative agent of colibacillosis, is a major problem for the poultry industry in the United States, resulting in significant losses annually (3). Additionally, recent reports, providing evidence of a link between APECcontaminated poultry (21) and extraintestinal pathogenic E. coli (ExPEC)-caused neonatal meningitis (24,44) and urinary tract infections in human beings (24,39), suggest that control of avian colibacillosis may have a beneficial impact on both avian and human health. Control of colibacillosis is problematic, with the increased restrictions on the use of antimicrobial agents in poultry making vaccine-based control, where appropriate, increasingly desirable.…”

Frequency of iss and irp2 genes by PCR method in Escherichia coli isolated from poultry with colibacillosis in comparison with healthy chicken in poultry farms of Zabol, South East of Iran

“…Detection, definition and determination of distribution of molecular pathotypes of APEC in poultry farms of every province of Iran, in different hosts, could be considered as a potential approach to control colibacillosis in the country (Johnson et al 2008). Our preliminary work used this objective in our study area to find the prevalent molecular pathotype in border region of Iran.…”