Pandemic extra-intestinal pathogenic Escherichia coli (ExPEC) clonal group O6-B2-ST73 as a cause of avian colibacillosis in Brazil.

Marcos Paulo Vieira Cunha,Antonio José Piantino Ferreira,Andre Becker Saidenberg,Terezinha Knöbl,Mônica Aparecida Midolli Vieira,Tânia Aparecida Tardelli Gomes,Andrea Micke Moreno,Dongsheng Zhou

doi:10.1371/journal.pone.0178970

Marcos Paulo Vieira Cunha, Antonio José Piantino Ferreira + Show 6 more

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https://doi.org/10.1371/journal.pone.0178970

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Abstract

Extra-intestinal pathogenic Escherichia coli (ExPEC) represent an emerging pathogen, with pandemic strains increasingly involved in cases of urinary tract infections (UTIs), bacteremia, and meningitis. In addition to affecting humans, the avian pathotype of ExPEC, avian pathogenic E. coli (APEC), causes severe economic losses to the poultry industry. Several studies have revealed overlapping characteristics between APEC and human ExPEC, leading to the hypothesis of a zoonotic potential of poultry strains. However, the description of certain important pandemic clones, such as Sequence Type 73 (ST73), has not been reported in food sources. We characterized 27 temporally matched APEC strains from diverse poultry farms in Brazil belonging to the O6 serogroup because this serogroup is frequently described as a causal factor in UTI and septicemia in humans in Brazil and worldwide. The isolates were genotypically characterized by identifying ExPEC virulence factors, phylogenetically tested by phylogrouping and multilocus sequence type (MLST) analysis, and compared to determine their similarity employing the pulsed field gel electrophoresis (PFGE) technique. The strains harbored a large number of virulence determinants that are commonly described in uropathogenic E. coli (UPEC) and sepsis associated E. coli (SEPEC) strains and, to a lesser extent in neonatal meningitis associated E. coli (NMEC), such as pap (85%), sfa (100%), usp (100%), cnf1 (22%), kpsMTII (66%), hlyA (52%), and ibeA (4%). These isolates also yielded a low prevalence of some genes that are frequently described in APEC, such as iss (37%), tsh, ompT, and hlyF (8% each), and cvi/cva (0%). All strains were classified as part of the B2 phylogroup and sequence type 73 (ST73), with a cluster of 25 strains showing a clonal profile by PFGE. These results further suggest the zoonotic potential of some APEC clonal lineages and their possible role in the epidemiology of human ExPEC, in addition to providing the first description of the O6-B2-ST73 clonal group in poultry.

Highlights

Extra-intestinal pathogenic Escherichia coli (ExPEC) are commonly isolated pathogens from a wide variety of diseases in animals and humans
All 27 strains showed the same Sequence Type 73 (ST73) by multilocus sequence typing (MLST), phylogenetic group B2, and the presence of genes encoding virulence factors that are found among ExPEC isolates (Table 1, Fig 1)
Our findings demonstrate close similarities with respect to the serogroup, virulence factors, phylogenetic group, and sequence type of ST73 avian pathogenic E. coli (APEC) strains to findings previously reported elsewhere for human ST73 ExPEC

Summary

Introduction

Extra-intestinal pathogenic Escherichia coli (ExPEC) are commonly isolated pathogens from a wide variety of diseases in animals and humans. In which most ExPEC belong to the predominant phylogroup B2 and, to a reduced degree, to phylotype D, and the multilocus sequence typing (MLST), which allows the assignment of closely related strains in clonal groups or complexes as a sequence type (ST). These standardized classifications have facilitated the identification and surveillance of pandemic strains that cause nosocomial and community outbreaks [2, 3]. This phenomenon, is of extreme concern regarding remaining antibiotic treatment options [4]

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