Production of cytotoxic necrotizing factor, verocytotoxin and haemolysin by pyelonephritogenic Escherichia coli.

Two hundred and thirty-two strains of Escherichia coli isolated from children with non-obstructive acute pyelonephritis (n=65), women with non-obstructive acute pyelonephritis (n=63) and the faecal flora of healthy children (n=33) and adults (n=71) were examined for cytotoxic necrotizing factor production, haemolysin synthesis, verocytotoxin production and expression of mannose-resistant haemagglutination of human erythrocytes. Forty-eight per cent of the pyelonephritogenic Escherichia coli strains produced cytotoxic necrotizing factor and 61 % produced haemolysin compared to 25 % and 27 % of faecal control strains (p<0.001 and p<0.001 respectively). Cytotoxic necrotizing factor production did not occur among the non-haemolytic Escherichia coli strains which confirms the close association between these two toxic factors. The bacterial phenotypes producing both haemolysin and cytotoxic necrotizing factor, and the phenotype expressing both these toxic factors and mannose-resistant haemagglutination occurred significantly more often in pyelonephritogenic strains than in faecal isolates (p<0.001). Haemolytic strains without the ability to produce cytotoxic necrotizing factor were more common in faecal isolates than in uropathogenic strains (p=0.05). Strains lacking the ability to synthesize both these toxins were also over-represented in faecal isolates (p<0.01). [ABSTRACT FROM AUTHOR]