Molecular Genetic and Functional Analysis of pks-Harboring, Extra-Intestinal Pathogenic Escherichia coli From India

Abstract

Colibactin, a genotoxin, encoded by the <i>pks</i> pathogenicity island of <i>Escherichia coli</i> belonging to the B2 phylogroup has been reported as a determinant of bacterial pathogenicity. The present study was carried out to detect the <i>pks</i> pathogenicity island in extraintestinal pathogenic <i>E. coli</i> (ExPEC) isolated from a tertiary hospital in Pune, India. Of 462 isolates analyzed, the <i>pks</i> genomic island was detected in 35 (7.6%) isolates, which predominantly belonged to pathogenic phylogroup B2 (97%), and harbored virulence genes such as <i>fimH, sfaD/E</i>, and <i>usp</i>. Biofilm formation assay revealed 21 of the 35 <i>pks-</i>carrying isolates to be strong (SBF > 1.0), 10 isolates to be moderate (SBF = 0.5-1.0), and 4 as weak (SBF < 0.5) biofilm formers. All of the <i>pks-</i>carrying isolates proved resistant against bactericidal activity of human serum. Assays carried out to detect antimicrobial susceptibility revealed 11% of these isolates to be multidrug resistant, 37% producing ESBL and 25% were positive for <i>bla</i> _CTX-M-15. The observed prevalence of multidrug resistance and colibactin producing characteristics among pathogenic <i>E. coli</i> belonging to phylogenetic group B2 advocate urgent need for broader surveillance in order to understand and prevent transmission of these ExPEC in community and hospital settings.