The immune response to urinary tract infections in childhood. I. Serological diagnosis of primary symptomatic infection in girls by indirect hemagglutination.

Determination of antibodies to E. Coli O antigen by indirect hemagglutination for detection of acute pyelonephritis was investigated in sequences of sera from 94 girls with their first known attack of symptomatic urinary tract infection. Using O antigen from the infecting bacterial strain or a standard strain increased antibody titres were found among pyelonephritis patients in 89% in unreduced sera (mainly 19 S antibodies) and in 81% in reduced sera (mainly 7 S antibodies) compared to a control material of 643 healthy children. Significant changes of these antibody titres occurred in 74 and 39% respectively. Analysis of maximal titres as well as titre changes in both unreduced and reduced sera showed diagnostically significant changes in two or more of these four parameters in 89% of patients with pyelonephritis. In contrast one parameter with such changes was found among the cystitis patients in only 5%. Employing a pool of 8 common O antigens, increased antibody titres were detected in 76% of patients with pyelonephritis. A larger pool of 68 antigens was no better and had a low capacity to detect 7 S antibodies. Optimal time for blood sampling was 2 to 3 weeks after onset of symptoms.