Frequent production of toxins byEscherichia colistrains isolated from human urinary tract infections: relation with haemagglutination

We have investigated the production of heat-labile enterotoxin (LT), Verotoxin (VT), cytotoxic necrotizing factor (CNF), haemolysis (Hly) and lethal activity for mice in 48 Escherichia coli strains isolated from patients with urinary tract infections. Mannose-resistant and mannose-sensitive haemagglutination in these strains were also studied. Among the total strains investigated, 50% were haemolytic, 50% synthesized CNF and 58% were lethal for mice. A total of 33 (69%) strains were toxigenic, showing positive results at least in one of the tests employed for toxin detection. No strain was positive for LT and VT production. We conclude that, in addition to haemolytic and haemagglutinating activities, the production of CNF was closely associated to virulence in E. coli strains isolated from urinary tract infections.