Extraintestinal Pathogenic Escherichia coli Strains of Avian and Human Origin: Link between Phylogenetic Relationships and Common Virulence Patterns

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) strains of human and avian origin show similarities that suggest that the avian strains potentially have zoonotic properties. However, the phylogenetic relationships between avian and human ExPEC strains are poorly documented, so this possibility is difficult to assess. We used PCR-based phylotyping and multilocus sequence typing (MLST) to determine the phylogenetic relationships between 39 avian pathogenic E. coli (APEC) strains of serogroups O1, O2, O18, and O78 and 51 human ExPEC strains. We also compared the virulence genotype and pathogenicity for chickens of APEC strains and human ExPEC strains. Twenty-eight of the 30 APEC strains of serogroups O1, O2, and O18 were classified by MLST into the same subcluster (B2-1) of phylogenetic group B2, whereas the 9 APEC strains of serogroup O78 were in phylogenetic groups D (3 strains) and B1 (6 strains). Human ExPEC strains were closely related to APEC strains in each of these three subclusters. The 28 avian and 25 human strains belonging to phylogenetic subcluster B2-1 all expressed the K1 antigen and presented no significant differences concerning the presence of other virulence factors. Moreover, human strains of this phylogenetic subcluster were highly virulent for chicks, so no host specificity was identified. Thus, APEC strains of serotypes O1:K1, O2:K1, and O18:K1 belong to the same highly pathogenic clonal group as human E. coli strains of the same serotypes isolated from cases of neonatal meningitis, urinary tract infections, and septicemia. These APEC strains constitute a potential zoonotic risk.

Prevalence of genes encoding virulence factors among Escherichia coli with K1 antigen and non-K1 E. coli strains

“…Three multiplex PCR assays were designed for simultaneous detection of: (i) neuC and sfa/foc, (ii) fimA and fimH, and (iii) hlyF, iutA and ibeA. Each VF gene was amplified using primers described by Moulin-Schouleur et al (2007) (Table 2) in a total volume of 25 ml containing 1 ml DNA, 1.56 PCR buffer, 2 mM MgCl 2, 5 nmol each dNTP (Promega), 12.5 pmol each primer (Laboratory of DNA Sequencing and Oligonucleotide Synthesis, IBB Polish Academy of Sciences, Poland) and 1 U Taq DNA polymerase (Promega). The PCR steps were as follows: initial denaturation at 94 uC for 3 min, followed by 30 cycles of denaturation at 94 uC for 1 min, annealing at the specific temperature for each multiplex reaction as follows: 58 uC (neuC and sfa/foc), 49 uC (fimA and fimH) or 51 uC (hlyF, iutA, and ibeA) ( Table 2) for 1 min, and extension at 72 uC for 1 min, followed by a final 10 min extension at 72 uC.…”

Colibacillosis in poultry: unravelling the molecular basis of virulence of avian pathogenicEscherichia coliin their natural hosts

“…Multi-locus sequence typing of O78 strains has revealed closely related clones to reside in different hosts and a strong correlation between virulence and clonal origin (Adiri et al, 2003). PCR-based phylotyping and multi-locus sequence typing have also revealed a link between APEC and human exPEC (Moulin-Schouleur et al, 2007), further suggesting the potential food-borne source of human exPEC.…”

Distribution of serotypes and virulence-associated genes in pathogenicEscherichia coliisolated from ducks

“…Also, recent reports have suggested APEC strains are linked with human diseases, such as urinary tract infection and neonatal meningitis, mostly caused by extraintestinal pathogenic E. coli (Rodriguez-Siek et al, 2005a;Ewers et al, 2007;Moulin-Schouleur et al, 2007;Mellata et al, 2009;Zhao et al, 2009). Moreover, Shiga-toxinproducing E. coli (STEC) has been demonstrated to exist in chickens or other birds, suggesting that poultry are a reservoir of STEC for humans (Parreira & Gyles, 2002;Grossmann et al, 2005).…”