Listeria monocytogenes in Different Specimens from Healthy Red Deer and Wild Boars

In the past, Listeria monocytogenes has been isolated from game feces and meat. However, less information is available on the occurrence of L. monocytogenes in other specimens originating from game animals. Hence, the aim of this study was to get an overview of the occurrence and distribution of L. monocytogenes in game animals by characterization of isolates from different matrices. For that purpose, samples were collected from red deer (Cervus elaphus), wild boars (Sus scrofa), and feed during the hunting season 2011-2012 in three different regions of Germany and Austria. Six samples from each animal were examined: tonsils, content of the rumen or the stomach, liver, intestinal lymph nodes, cecum content, and feces. Nineteen of 45 red deer and 12 of 49 wild boars were found to be positive for L. monocytogenes as well as 4 of 22 pooled feed samples. L. monocytogenes was isolated most frequently from the rumen of red deer (14 of 19) and the tonsils of wild boars (7 of 12). Serotypes 1/2a, 1/2b, 4a, and 4b were detected in samples of game animals and feed, and serotypes 1/2a and 4b were the most prevalent serotypes. The presence of L. monocytogenes serotype 4a had not yet been described in red deer. This might be due to the fact that it was only isolated from the content of rumen and that no other study has yet examined ruminal content. Pulsed-field gel electrophoresis showed a wide variety of strains. Some strains occurred in both species and feed samples, but one strain was dominant in one region. The results show that red deer and wild boars can be carriers of L. monocytogenes in different matrices, although the feces samples can be negative.