The molybdate transport protein ModA regulates nitrate reductase activity to increase the intestinal colonization and extraintestinal dissemination of Klebsiella pneumoniae in the inflamed gut

Inflammatory bowel disease (IBD) is an inflammatory disorder of the gut, and host-derived nitrate in IBD confers a luminal growth advantage upon Escherichia coli and Salmonella typhimurium through nitrate respiration in the inflamed gut. However, the impact of nitrate on the growth and pathogenicity of K. pneumoniae in this microenvironment is poorly understood.

In this study, we used oral administration of dextran sodium sulfate to induce IBD in mouse models. We then analyzed the colonization levels of K. pneumoniae wild-type (WT), the nitrate reductase gene mutant strains (ΔnarG, ΔnarZ and ΔnarGΔnarZ), and the molybdate uptake gene mutant strain (ΔmodA) in the inflamed intestinal tract. Results showed that the growth, intestinal colonization, and extraintestinal dissemination of K. pneumoniae were increased in the intestines of dextran sulfate sodium (DSS)-treated mice.