Abstract
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. 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. 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 IV536 was common in both ExPEC and commensal isolates. 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.
Highlights
Extraintestinal pathogenic Escherichia coli (ExPEC) is associated with various diseases such as urinary tract infections, neonatal meningitis and septicemia
ExPEC are often classified in different groups according to the anatomical site of infection, with uropathogenic E. coli (UPEC) being associated with urinary tract infections (UTIs) [1]
Among the 96 patients infected with ExPEC, 90 (93.8%) were from urinary tract infections that were categorized as cystitis (91.1%), urosepsis (6.7%) and pyelonephritis (2.2%) (Table 2)
Summary
Extraintestinal pathogenic Escherichia coli (ExPEC) is associated with various diseases such as urinary tract infections, neonatal meningitis and septicemia. There are many virulence genes associated with ExPEC, including papC (P fimbrial usher), papG (P fimbrial adhesin), ecpA (extracellular adhesive fimbriae), iroN (salmochelin siderophore receptor), fyuA (yersiniabactin siderophore receptor), iutA (aerobactin siderophore receptor), ompTp (episomal outer membrane protein OmpT), tsh (temperature sensitive hemagglutinin), hlyF (hemolysin F), hlyA (hemolysin) and iss (serum resistance associated protein) [3,4,5]. These factors are commonly found in ExPEC isolated from UTIs and are less common in most fecal commensal E. coli [6]. As UPEC originate from the intestinal tract, some fecal commensal strains may contain these virulence genes
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