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.
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