Indirect hemagglutination employing enterobacterial common antigen and Yersinia somatic antigen: a technique to differentiate brucellosis from infections involving cross-reacting Yersinia enterocolitica.

The existence of enterobacterial common antigen in Yersinia enterocolitica and its absence in Brucella abortus were utilized in an attempt to provide a method to distinguish Brucella infections from infections with cross-reacting Yersinia. The indirect hemagglutination test was employed for this purpose. In experimental laboratory animals, the presence of anti-enterobacterial common antigen was found to be indicative of prior exposure to Y. enterocolitica rather than B. abortus. In cattle, however, low titers of anti-enterobacterial common antigen were present in all animals. It was observed that anti-enterobacterial common antigen titers either equaled or exceeded anti-Yersinia O titers in Yersinia-exposed animals, whereas in animals infected with B. abortus the anti-Yersinia O titer generally exceeded the anti-enterobacterial common antigen titer.