Frequency of Escherichia coli strains producing the cytotoxic necrotizing factor (CNF1) in nosocomial urinary tract infections.

The presence of cytotoxic necrotizing factor 1 (CNF1), together with various associated virulence factors (alpha-haemolysin, P-, S- and A-fimbriae), was screened in 175 uropathogenic Escherichia coli strains isolated from hospitalized adult patients. The cnf1 gene was detected in 30% of the selected strains independently of the severity of the clinical urinary infection. A significant association between CNF1, haemolytic activity and the products of the pap/sfa genes was found. However, CNF1 appeared not to play a major role in nosocomial E. coli urinary tract infections.