Abstract
One hundred and sixty-eight strains ofEscherichia coli isolated from 84 men and 84 women who had urinary tract infections (134 cases) or bacteremia of urinary tract origin (34 cases) were assessed for their carboxylesterase B electrophoretic types B and B -haemolysin and MRHA productions. The strains isolated from males were more frequently of type B, haemolytic and both haemolytic and haemagglutinating than those isolated from females. The strains isolated during bacteremia were more frequently haemolytic and haemag glutinating than those obtained from urinary tract infections. Type B strains were more frequently resistant to antimicrobial agents than type B strains. The results reinforced the distinction, in terms of virulence and antibiotic sensitivity, between B and B strains and demonstrated the influence of the sex of patients on the host-parasite interaction during urinary tract infections.