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

Arya Suresh,Sabiha Shaik,Lothar H Wieler,Niyaz Ahmed,Arif Hussain,Amit Ranjan,Ramani Baddam,Munirul Alam,Savita Jadhav

doi:10.3389/fmicb.2018.02631

Abstract

Colibactin, a genotoxin, encoded by the pks pathogenicity island of Escherichia coli belonging to the B2 phylogroup has been reported as a determinant of bacterial pathogenicity. The present study was carried out to detect the pks pathogenicity island in extraintestinal pathogenic E. coli (ExPEC) isolated from a tertiary hospital in Pune, India. Of 462 isolates analyzed, the pks genomic island was detected in 35 (7.6%) isolates, which predominantly belonged to pathogenic phylogroup B2 (97%), and harbored virulence genes such as fimH, sfaD/E, and usp. Biofilm formation assay revealed 21 of the 35 pks-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 pks-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 blaCTX-M-15. The observed prevalence of multidrug resistance and colibactin producing characteristics among pathogenic E. coli 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.

Highlights

Extraintestinal pathogenic Escherichia coli (ExPEC), apart from being a seasoned nosocomial pathogen is an important cause of community-acquired (Johnson and Russo, 2002) and other infections such as urinary tract infection, sepsis, neonatal meningitis, and colibacillosis in humans and animals (Kaper et al, 2004; Smith et al, 2007)
Some of these known secreted toxins comprise of important genotoxins, such as cytolethal distending toxins (CDT’s), cycle inhibiting factors and cytotoxic necrotizing factors (CNF’s) which can directly regulate the cell cycle of the host (Nougayrède et al, 2005)
A total of 462 E. coli isolates from our collection were screened for the presence of pks island, of which 35 were found to be positive for all the four targeted genes amplified from flanking and internal regions

Summary

Introduction

Extraintestinal pathogenic Escherichia coli (ExPEC), apart from being a seasoned nosocomial pathogen is an important cause of community-acquired (Johnson and Russo, 2002) and other infections such as urinary tract infection, sepsis, neonatal meningitis, and colibacillosis in humans and animals (Kaper et al, 2004; Smith et al, 2007). Some of these known secreted toxins comprise of important genotoxins, such as cytolethal distending toxins (CDT’s), cycle inhibiting factors (cif ’s) and cytotoxic necrotizing factors (CNF’s) which can directly regulate the cell cycle of the host (Nougayrède et al, 2005). Colibactin is another important genotoxin produced by a 54-kb pathogenicity island known as pks island harbored by the members of Enterobacteriaceae (Nougayrède et al, 2006). The cytopathic effect of these genotoxins is mediated by live bacteria and requires a direct contact with the host cell (Nougayrède et al, 2006)

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Conclusion