Influence of the Gut Microbiota Composition on Campylobacter jejuni Colonization in Chickens

Abstract

The <i>Campylobacter jejuni</i>-host interaction may be affected by the host's gut microbiota through competitive exclusion, metabolites, or modification of the immune response. To understand this interaction, <i>C. jejuni</i> colonization and local immune responses were compared in chickens with different gut microbiota compositions. Birds were treated with an antibiotic cocktail (AT) (experiments 1 and 2) or raised under germfree (GF) conditions (experiment 3). At 18 days posthatch (dph), they were orally inoculated either with 10⁴ CFU of <i>C. jejuni</i> or with diluent. Cecal as well as systemic <i>C. jejuni</i> colonization, T- and B-cell numbers in the gut, and gut-associated tissue were compared between the different groups. Significantly higher numbers of CFU of <i>C. jejuni</i> were detected in the cecal contents of AT and GF birds, with higher colonization rates in spleen, liver, and ileum, than in birds with a conventional gut microbiota (<i>P</i> < 0.05). Significant upregulation of T and B lymphocyte numbers was detected in cecum, cecal tonsils, and bursa of Fabricius of AT or GF birds after <i>C. jejuni</i> inoculation compared to the respective controls (<i>P</i> < 0.05). This difference was less clear in birds with a conventional gut microbiota. Histopathological gut lesions were observed only in <i>C. jejuni</i>-inoculated AT and GF birds but not in microbiota-colonized <i>C. jejuni</i>-inoculated hatchmates. These results demonstrate that the gut microbiota may contribute to the control of <i>C. jejuni</i> colonization and prevent lesion development. Further studies are needed to identify key players of the gut microbiota and the mechanisms behind their protective role.