Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Microbiology and Immunology

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, cytotoxic activity and haemagglutination and their relations to the following virulence genes: hlyA, cnf-1 and papC, by using multiplex PCR. Fluoroquinolones susceptibility was done using disk diffusion method.The results showed that 30% of the isolates were Ý- haemolytic, 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. We found that hlyA gene was significantly detected in the Ý- haemolytic than non- haemolytic isolates. As regard fluoroquinolones susceptibility, 60% of the isolates were resistant to the used fluoroquinolones with no significant difference between resistant and susceptible isolates as regard virulence factors and genes

Issued also as CD