The frequent use of antimicrobials in commercial poultry production has raised concerns regarding the potential impact of antimicrobials on human health due to selection for resistant bacteria. Several studies have reported similarities between extraintestinal pathogenic Escherichia coli (ExPEC) strains isolated from birds and humans, indicating that these contaminant bacteria in poultry may be linked to human disease. The aim of our study was to analyze the frequency of antimicrobial resistance and virulence factors among E. coli strains isolated from commercial chicken carcasses in Paraná, Brazil, in 2007 and 2013. A total of 84 E. coli strains were isolated from chicken carcasses in 2007, and 121 E. coli strains were isolated in 2013. Polymerase chain reaction was used to detect virulence genes (hlyF, iss, ompT, iron, and iutA) and to determine phylogenetic classification. Antimicrobial susceptibility testing was performed using 15 antimicrobials. The strains were also confirmed as extended-spectrum β-lactamase (ESBL)-producing E. coli with phenotypic and genotypic tests. The results indicated that our strains harbored virulence genes characteristic of ExPEC, with the iutA gene being the most prevalent. The phylogenetic groups D and B1 were the most prevalent among the strains isolated in 2007 and 2013, respectively. There was an increase in the frequency of resistance to a majority of antimicrobials tested. An important finding in this study was the large number of ESBL-producing E. coli strains isolated from chicken carcasses in 2013, primarily for the group 2 cefotaximase (CTX-M) enzyme. ESBL production confers broad-spectrum resistance and is a health risk because ESBL genes are transferable from food-producing animals to humans via poultry meat. These findings suggest that our strains harbored virulence and resistance genes, which are often associated with plasmids that can facilitate their transmission between bacteria derived from different hosts, suggesting zoonotic risks.
Introduction: Extraintestinal pathogenic Escherichia coli (ExPEC) is associated with various diseases such as urinary tract infections, neonatal meningitis and septicemia. There are many virulence factors (VF) encoded by genes in ExPEC, including papC, papG, ecpA, iroN, fyuA, iutA, ompTp, tsh, hlyF, hlyA and iss. These virulence genes may be present in pathogenicity islands (PAI) or plasmids. Methodology: In this study, we analyzed the presence of VF encoding genes, PAI sequences and phylogenetic groups of 96 ExPEC strains isolated from the urine and blood of patients at the University Hospital of Londrina, and we compared them with 50 faecal commensal strains from healthy individuals. Results: The VF fyuA (65.60%) was detected in pathogenic strains and commensal strains (46%). A comparison of the distribution of ExPEC and commensal strains in the phylogenetic groups showed that more ExPEC strains belonged to group B2 whereas more of the commensal isolates belonged to group A. The distribution of the seven PAI sequences between commensal strains and ExPEC strains showed that PAI IV 536 was common in both ExPEC and commensal isolates. Conclusions: These results showed that the ExPEC strains that belonged to group B2 had more PAI sequences compared to those of the other groups, especially group B1, which had virulence genes but the lowest percentage of PAI sequences, which leads us to conclude that the virulence of ExPEC strains characterized as B2 is likely attributed to PAI encoded genes, whereas the virulence of ExPEC strains belonging to phylogenetic group B1 is likely due to plasmid encoded virulence genes.
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