Experimental mixed infection with Yersinia enterocolitica and Listeria monocytogenes in guinea pigs.

The pathogenesis and the cell immune response (CIR) of guinea pigs after mixed infection with Y. enterocolitica and L. monocytogenes was investigated. The guinea pigs were infected per os with 1.1 x 10(9) CFU Y. enterocolitica 0:3, (pYV+) and four days later with 1.1 x 10(9) CFU L. monocytogenes 4B. Clinical, paraclinical and morphological findings attending the infectious process were followed in dynamics up to the 28th day post infection (p.i.) with L. monocytogenes. The phagocyting activity of alveolar macrophages (aMa) was suppressed against Y. enterocolitica, in contrast to peritoneal macrophages (pMa) engulfing yersiniae more actively at the end of the study. Moreover, the tendency of augmented entering in both phagocytes of L. monocytogenes cells was well demonstrated, starting at the earlier intervals of examination. Histopathological studies showed a purulent meningoencephalitis and a catarrhal pneumonie, non-reactive micronecroses in the spleen and lymphadenitis catarrhalis in the mesenteric lymph nodes. Analysis of the T-cell immune response (T-CIR) showed maximal values in the spleen lymphocytes after Y. enterocolitica and L. monocytogenes mixed infection. The B-CIR occurred early (at the 7th day p.i.) and was maximal at the 28th day p.i. in blood lymphocytes. The results obtained demonstrated that the mixed infection of guinea pigs with Y. enterocolitica and L. monocytogenes runs has a non lethal, generalized illness with a dominant role of L. monocytogenes cells.