Cold Agglutinins in Listeria Monocytogenes Infections

Cold agglutinins were demonstrated in the serum of a patient with Listeria monocytogenes meningitis recently studied by us. The titers of cold agglutinins were significant and tended to parallel the titers of Listeria antibodies. False-positive heterophil antibody tests were easily produced by the cold agglutinins as described previously by Zarafonetis.1Further serological studies were done to evaluate the relationship between Listeria and cold agglutinins. This patient's course was also considered sufficiently unusual to report in some detail. Infectious mononucleosis has been disputedly related to L. monocytogenes during the last 27 years. Shortly after these Grampositive bacilli were identified and described as causing a marked monocytic reaction in animals, Nyfeldt, in Copenhagen, reasoned that here at last was the likely etiological agent of infectious mononucleosis. Investigation of all his patients with this disease soon proved rewarding, as he isolated a culture of L. monocytogenes from the blood of one such