Comparative Analysis of Virulence Factors of Escherichia coli from Non-enteric Infections

There is correlation between certain properties of E. coli strains and capacity of the strain to cause non-enteric infections. The aim of this study was to compare Escherichia coli strains isolated from non-enteric infection with those from faeces of normal healthy individuals, for their possession of haemolysin, mannose- resistant-haemagglutinin, colicin, protease, cell surface hydrophobicity and antibiotic susceptibility. Source wise distribution of the haemolytic strains were 60% from urine, 41.7% from blood, 33.3% from peritoneal fluid, 50% from pus and 26.7% from stool. Colicinogeny was found to be a common property of both clinical and faecal E. coli and only a few of the urine and blood isolates (52 and 41.7%, respectively) exhibited colicin V activity. Mannose Resistant Haemagglutinin (MRHA) test showed positive (MRHA+) reaction for 47.7% of the clinical E. coli isolates, while this value was only 26.7% for the controls. A significant association between haemolysin production and MRHA of human type O erythrocytes was found, as 75.86% of the Hly+ E. coli strains were also MRHA+. The data obtained in this study suggested that haemolysin production, MRHA of human type O erythrocytes and hydrophobic cell surface might be important for E. coli strains to initiate and sustain infection at non-enteric sites.