Duration of antibody responses to common enterobacterial and O antigens of children with pyogenic peritonitis.

Children with pyogenic peritonitis folloiwng appendicits produce antibodies against the common enterobacterial antigen (CA) in unusually high titers when compared to patients with salmonellosis, shigellosis, or urinary tract infection. The duration of this antibody response was determined in 19 children observed over a period of up to 31 months after the acute illness. CA antibody titers decreased significantly in 70% of the patients during the first year and in 91% of those studied between 13 and 31 months after the infection. In the majority (71%) of patients the antibody titers returned to pre- or near pre-infection levels within 31 months after the acute illness. Only in a few patients (19%) were near maximal titers maintained during the observation period. The titers of antibodies against the O antigens of the infecting microorganisms also decreased in the majority of subjects during the follow-up period of observation. These findings may be of importance in connection with studies on the immune response of patients with urinary tract and other infections.