Detection of antigens from gram-negative bacilli in urine of children with urinary tract infections. I. Common antigen of Enterobacteriaceae.

Enterobacterial common antigen (ECA) has attracted considerable interest since the original publication by Kunin in 1962. In the present study we demonstrated this antigen directly in the urine from patients with urinary tract infections (UTI) elicited by enterobacteria. Sheep erythrocytes were incubated with UTI urine; this resulted in their coating with ECA, which was studied by means of hemagglutination by anti-ECA serum. Test tube hemagglutination and the more simple slide hemagglutination were employed and with both procedures similar results were obtained. Positive results were observed in 94-99% of urine specimens from enterobacterial UTI collected in The Buffalo Children's Hospital in the 1960s. ECA in urine could also be demonstrated by hemagglutination inhibition. In this test, antibodies in anti-ECA serum were neutralized as a result of incubation of this serum with urine, and agglutination by the antiserum of sheep erythrocytes coated with a standard ECA preparation was prevented or reduced. By means of this latter test, ECA could be demonstrated in 67-88% of urine specimens from enterobacterial UTI. The possible diagnostic application of these tests has been discussed.