A high incidence of negative results in the standard agglutination test for tularemia was found to be due to the presence of inhibiting factors incomplete antibodies. The latter could be more or less aggregated by an excess of antigens so that agglutination took place. Positive reactions were obtained also if an excess of tularemia bacteria in the form of a specific suspension of phenol-killed bacteria was added to dilutions of the sera containing such incomplete antibodies. Methods for conglutination, Coombs and consumption tests for tularemia were developed for demonstration of the inhibiting factors. This last is a test not heretofore used in serological diagnosis of infectious diseases. It was determined further that latex particles of a certain size charged with tularemia bacteria are also flocculated by tularemia antibodies. Author
Trans. of Zentralblatt fuer Bakeriologie, Parasitenkunde und Infektionskrankheiten. Abt. 1. Originale (West Germany) v180 p254-263 1960.