INTERACTIONS OF LISTERIA-MONOCYTOGENES, LISTERIA-SEELIGERI, AND LISTERIA-INNOCUA WITH PROTOZOANS

Cocultures of three Listeria species, L. monocytogenes, L. seeligeri, and L. innocua with Acanthamoeba castellanii, and Tetrahymena pyriformis, respectively, were investigated. The Listeria were ingested intracellularly by the protozoans. However, they were not killed, on the contrary, they survived. The two hemolytic Listeria species, i.e. L. monocytogenes and L. seeligeri ruptured their host cells completely after a few days and became free. Subsequently, they died. On the other hand, the apathogenic L. innocua partially lysed the protozoans and coexisted intracellularly as well as extracellularly for some weeks. Additionally, cocultures of L. monocytogenes, Escherichia coli, Salmonella typhimurium, and A. castellanii, T. pyriformis, respectively, were studied. The results showed that both protozoans possess similar distinct preferences for the Salmonella and Listeria, but E. coli was not desirable ‘prey.’ Ingested S. typhimurium were killed but L. monocytogenes survived. The observed phenomena provide a special insight regarding L. monocytogenes infection in man and animals in respect to the different behaviour patterns of the three Listeria species investigated. © 1990, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.