Lower prevalence of hlyD, papC and cnf-1 genes in ciprofloxacin-resistant uropathogenic Escherichia coli than their susceptible counterparts isolated from southern India

Summary: Objective: The study was conducted to determine the association of the hlyD, papC and cnf-1 virulence genes with drug resistance in uropathogenic Escherichia coli (UPEC) isolated from cases of urinary tract infection (UTI). Method: A total of 193 E. coli strains isolated from symptomatic cases of UTI in a tertiary care teaching hospital in Raichur, Northern Karnataka, India were included in the study. The antibiotic susceptibility pattern was determined by Kirby–Bauer's Disk Diffusion method, and the strains resistant to any of the third generation cephalosporins tested were further confirmed for extended-spectrum beta-lactamase (ESBL)-production by an E-strip test. Genotypic virulence markers, namely, hlyD, papC and cnf-1, were detected by the uniplex PCR method and the phylogenetic characterization was performed by a multiplex PCR assay. Results: The majority of the E. coli isolates belonged to the B2 phylogenetic group were significantly associated with ciprofloxacin-sensitivity and non-ESBL production (p < 0.05). An increased prevalence of ciprofloxacin-sensitive strains over ciprofloxacin-resistant strains were observed among the UPEC isolates harboring the papC (72.9% vs. 40.2%; p < 0.001), hlyD (43.7% vs. 21.6%; p < 0.001) and cnf-1 (30.2% vs. 12.3%; p < 0.05) genes. The presence of a multivirulent gene in the non-ESBL E. coli strains (44.5%) was significantly higher (p < 0.05) than in the ESBL-producing strains (21%). Conclusions: Among the UPEC isolates, the predominant B2 phylogenetic group was significantly associated with the ciprofloxacin-sensitive strains, as well as with the non-ESBL E. coli strains. The genotypic virulence markers of UPEC were associated with ciprofloxacin-sensitivity, and a significant number of the non-ESBL strains harbored multivirulent genes. The relationship between the presence of the virulence genes and ESBL production was complex and warrants further intensive studies. Keywords: Uropathogenic Escherichia coli, Diabetes mellitus, Virulence genes, Phylogenetic characterization, ESB

Enhanced Adhesion and Cell Damage by Escherichia coli Harboring hly, papC and cnf-1genes to the Uroepithelium in Diabetic Mouse Bladder Model

The in-vivo mouse bladder model was sought to determine the effect of virulent uropathogenic E. coli (UPEC) strain harboring hly, papC and cnf-1 genes on uroepithelium of diabetic mouse bladder infected transurethrally. The female BALB/c mice aged between 6-8 weeks were used in the study. The diabetes was induced by subcutaneous injection of alloxan hydrate (80mg / kg body weight) in mice. Two UPEC strains, one with hly, papC and cnf-1 virulent genes and the other (hypovirulent) without hly, cnf-1 and papC genes were selected for the study. The animals were anesthetized and 50 µl of bacterial inoculum was instilled in to bladder of DM and non-DM mice using specially devised mice catheter. The mice were sacrificed at 4 hrs, 24 hrs and 48 hrs of post infection, and the bladder was removed aseptically. One half of the bladder was homogenized and bacterial culture was performed. The other half of the bladder was used to document bacterial adhesion and invasion by histopathology and scanning electron microscopy. The exaggerated consequence of virulent UPEC strain on diabetic mouse bladder model was documented as enhanced adhesion and extensive damage of the uroepithelium of the bladder. However, hypovirulent UPEC strain failed to produce observable pathophysiological effect. Many of the UPEC were in the filamentous form and occasionally seen looping within and between adjacent superficial cells to escape from immune mechanism like micturation and exfoliation