Abstract
Serological investigations in infections caused by hemolytic streptococci and by Yersinia enterocolitica (Y. ent.) can be diagnostically decisive. Here are presented the results of 2 extensive serologic investigations of a population of school children (n = 929) and of hospitalized patients (n = 2121). It is shown that only very high titers of streptococcal antibodies were of diagnostic value in single samples as most other titers had the same distribution and frequency in the healthy population. Titers of antibodies to Y. ent. were elevated 5 times more often in the hospital patients than in the healthy population. Antibodies to Y. ent. were approximately at the same level in all age groups in contrast to the streptococcal antibodies, which decreased with age. In about 4% of the 2121 patients investigated elevated antibody titers to both bacteria were found simultaneously. The differential diagnosis may be difficult in such cases especially if they exhibit symptoms of rheumatic fever.