Patterns of antibody response of children with infections of the urinary tract.

Abstract

Extract: An immunologic study was carried out on 140 children with infections of the urinary tract. The diagnosis was based on clinical, roentgenologic, urologic, and bacteriologic findings. Of the patients, 37 (26%) had acute infection and the remainder (103 children, 74%) had chronic or recurrent infection. The hemagglutination test was used to measure the antibody levels against the O antigens of the urinary isolates. The patients were studied for a period of 1–7 years.An antibody response was documented in all but 10.7% of the subjects. Multiple antibody responses occurred in 55% and single antibody responses in 34.3% of the patients. There was no significant difference in the antibody responses to commonly encountered serogroups of Escherichia coli and other bacteria less frequently found in urinary tract infection. In 17 subjects, the antibody titer decreased rapidly within 2–8 weeks, and in 9 subjects reinfection with the microorganisms of identical serogroups led to a recall antibody response. It was shown that in 14 subjects (10%), minimal bacteriuria was accompanied by the production of the corresponding O antibodies, and in an additional 7 subjects (5%), asymptomatic bacteriuria, following or preceding overt infection, led to a specific antibody response.Continued production of O antibodies over many months was observed following overt infection even in the absence of persisting bacteriuria; in other patients, however, even prolonged bacteriuria resulting from identical serogroups was not associated with the production of the corresponding O antibodies.It is suggested that determination of the immune response of patients with urinary tract infection may aid in the identification of the etiologic role of urinary isolates, even when present in small numbers; may document infection by two or more antigenically unrelated microorganisms; and may help in the differentiation of relapse and reinfection. Thus, determination of the immune response may be a useful tool in the elucidation of certain aspects of this frequent, but incompletely understood disease.Speculation: Because infectious agents or their antigens must reach cells of the immune apparatus to elicit an antibody response, documentation of the production of specific antibodies may aid in the differentiation between true infection and urinary contamination, between reinfection and relapse, and in ascertaining the clinical signification of minimal bacteriuria. It may be speculated that since titers of O antibodies decrease substantially a few months after recovery from shigellosis and salmonellosis, persistent elevated antibody titers against O antigens of urinary pathogens are associated with continued antigenic stimulation and may reflect continuation of the pathologic processes.