Serum resistance of Escherichia coli strains causing urinary tract infection and diarrhoea in relation to alpha haemolysin production and O type.
A total of 46 alpha-hemolytic and 40 non-hemolytic clinical isolates of Escherichia coli were collected from pediatric patients with urinary tract infection and diarrhoea. Of 39 (84.7%) alpha-hemolytic strains and 27 (67.5%) non-hemolytic strains were resistant to 10% serum and there was no significant difference between urinary and stool isolates. On the contrary when 100% serum was used, 22 (47.8%) of the alpha-hemolytic and 7 (17.5%) of the non-hemolytic strains were resistant (p<0.01). and significantly greater resistance was found in urinary tract infection than from the stool samples (47% versus 24%, p<0.01). Serum resistance was higher in serogroups O6, O18 and O75. Production of alpha-hemolysin was more frequent in serogrops O2, O6, O8, O18 and O75. Thus, the resistance to human serum can determine clinical significance of Escherichia coli from different sources and alpha-hemolysin contributes to the virulence of Escherichia coli in initiation and perpetuation of clinical infection.
Rizvi
Meher
M
Department of Microbiology, Maulana Azad Medical College, New Delhi.
Kumar
Surinder
S
D015373:Bacterial Typing Techniques; D001770:Blood Bactericidal Activity; D003967:Diarrhea / Q000382:microbiology; D004926:Escherichia coli / Q000145:classification* / Q000472:pathogenicity / Q000502:physiology; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis; D006460:Hemolysin Proteins / Q000096:biosynthesis; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D019081:O Antigens; D014552:Urinary Tract Infections / Q000382:microbiology*; D014774:Virulence
D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D019081:O Antigens