diagnostic role of the enterobacterial common antigen in haematobiasis associated with urinary tract infection

ABSTRACT

The enterobacterial common antigen [ECA] is a common antigenic determinant shared by members of the family Enterobacteriaceae. The antigen modifies erythrocytes for agglutination by ECA antibody. This property has been of great help in the diagnosis of Enterobacteria as causative pathogens of various infections. The present study comprised 62 adult patients and 14 healthy controls. All patients suffered from different stages of urinary schistosomiasis associated with urinary tract infection [UTI]. Cancer bladder was also associated in 16 of the patients. They were further categorized accorrding to the number of isolated pathogens and accordingly intensity of infection into significant counts of > 100, 000 cfu/ml of Enterobacteria in 45 patients, insignificant counts < 100, 000 cfu/ml of Enterobacteria in 7 patients, significant Gram positive bacteruria in 8 patients and Candida albicans in 2 patients. Ten of the healthy controls bad sterile urine and 4 revealed asymptomatic bacteruria due to Enterobacteria. ECA was assayed in urine of all subjects by means of passive haemagglutination using slide and microtitration plate techniques. The ECA antigen was detected by slide test in 37.8% and in 40% by microtitration plate in cases of significant bacteruria due to Enterobacteria and in 42.8% and 57% in case of insignificant count due to Enterobacteria. ECA was not detected in urine of apparently healthy subjects nor in cases of Gram positive bacteruria or Candiduria; the sensitivity, specificity and diagnostic efficacy of the microtitration plate test being 42.5, 100% and 71% respectively. It is concluded that ECA+ represent a virulence factor which may contribute to the pathogenesis of UTI irrespective of the bacterial count. The ECA- strains may also cause UTI in high risk patients suffering from predisposing urinary lesions