[The virulence of E. coli strains isolated in urinary infections]

E. coli has been considered to be the most common pathogenic agent associated with the urinary tract infections. The pathogenic features of E. coli strains mainly the adherence, hemolysine and cytotoxine production (CNF) correlated with the affiliation to a specific serological type, provided a subject of active research. In the present study 104 strains of E. coli isolated in patients with urinary tract infections (hospitalised children and adults and outpatient children) were tested for their pathogenic features. The pyelonephritogenic capacity was assessed by the manose-resistant haemagglutination (HAMR) tested with human erythrocytes in 42.30% of strains. The haemolysine production was found in a significant number of strains (32.60%; 38.20% of this percentage enhanced the strains virulence by toxin elaboration (CNF)). The haemolysine production was mostly observed in the strains isolated in hospitalised children while the HAMR was more frequent in outpatient children. The increased incidence of the O6 serogroup among the uropathogenic E. coli strains (41.40%) was mainly recorded in hospitalised children; this finding indicates the O6 serogroup circulation within the health care units. The determination of the pathogenic features, chiefly of the pyelonephritogenic ones has been very useful for the disease prognosis and treatment.