SERUM RESISTANCE IN ESCHERICHIA-COLI STRAINS CAUSING ACUTE PYELONEPHRITIS AND BACTEREMIA

The capacity of Escherichia coli to resist the bactericidal action of serum was examined in 367 clinical isolates obtained from children wit h acute pyelonephritis (n = 57), adults with acute pyelonephritis (n = 55), non-diabetic patients with bacteraemia (n = 101), diabetic patie nts with bacteraemia (n = 65) and from the faecal flora of healthy con trols (n = 89). The incidence of serum-resistant E. coli strains was s ignificantly higher in pyelonephritogenic strains from children and ad ults (93% and 82%) as compared to faecal control strains (57%, p < 0.0 01 and p < 0.005 respectively). Strains causing bacteraemia in non-dia betic and diabetic patients were more often serum resistant (72% and 8 0%) as compared to control strains (p < 0.05 and p < 0.001 respectivel y). The frequency of serum-sensitive strains was similar in diabetic p atients with decreased renal function or proteinuria compared to those with normal renal function. There were no significant correlations be tween serum resistance of E. coli and expression of P fimbriae, type I fimbriae or mannose-resistant haemagglutination, cell surface hydroph obic properties, production of aerobactin, haemolysin or cytotoxic nec rotizing factor in 53 pyelonephritogenic strains from adult patients.