Important Virulence Factors and Related Genes in Uropathogenic E. coli and their Relation to Fluoroquinolone Resistance

Escherichia coli (E. coli) is the predominant pathogen causing urinary tract infection. E. coli expresses a wide spectrum of virulence factors that enable it to cause the disease. The present study was conducted on 50 E. coli isolates to assess some important phenotypic virulence factors of E. coli: haemolytic activity, cytotoxicity and haemagglutination and their relations to the following virulence genes: hlyA, cnf-1 and papC. Fluoroquinolones susceptibility was also assessed. Fifty E. coli isolates were isolated from non-hospitalized patients with UTIs and identified by colony morphology and standard biochemical reactions. The isolates were examined phenotypically for haemolytic activity using 5% sheep blood agar, cytotoxicity by their cultivation on HEp-2 cell line and haemagglutination of group O human RBCs. Virulence genes were detected by multiplex PCR. Fluoroquinolones susceptibility was done using disk diffusion method. Phenotypic methods showed that 30% of the isolates were bhaemolytic, 18% of the isolates showed haemagglutination with human RBCs, with higher prevalence for MRHA (12%) than MSHA (6%), and 92% of the isolates showed morphological changes, detachment and lysis in HEp-2 cells. Multiplex PCR showed that the most prevalent gene was cnf-1 (30%), while 26% of isolates were positive for hlyA and 26% of isolates were positive for papC. Only one UPEC isolate showed the simultaneous presence of papC, cnf-1 and hlyA, while 10 isolates were harbouring hlyA and cnf-1, 2 isolates were harbouring cnf-1 and papC genes and 2 isolates were harbouring hlyA and papC simultaneously. Fluoroquinolones susceptibility showed that 60% of the isolates were resistant to the used fluoroquinolones.