AGGLUTINATING ANTIBODIES FOR LISTERIA MONOCYTOGENES IN HUMAN SERUM

Abstract

The sera of 468 persons were tested for antibodies against Listeria monocytogenes. A somatic antigen was prepared using a strain classified in serological type 4 of the Paterson grouping. 23.3% of the samples gave no reaction in the 1:25 dilution while 52.8% gave trace reactions in that dilution. Additional reactions were as follows: 17.1% partial in 1:25 (half the antigen agglutinated), 1.5% complete in 1:25, 4.7% complete in 1:25 and partial in 1:50, and 0.6% complete in 1:50 and partial in 1:100. Seventeen individuals had histories of infectious mono-nucleosis, but there was no apparent correlation between these events and the somatic agglutinin titers. The presence of agglutinins to L. monocytogenes in 77% of the sera tested here is reported, since it may serve as a reference in evaluating serological tests for listeriosis in man. The significance of Listeria agglutinins would seem to depend upon detection of marked titer changes associated with a clinical episode.