Repetitive exposure to non-typhoidal Salmonellae is an environmental risk factor for colon cancer

Abstract

During its infectious cycle, Salmonella exploits its host by targeting and manipulating essential signalling pathways. This may disrupt cellular integrity and induce oncogenic transformation. Chronic S. Typhi infection can indeed cause gallbladder cancer whereas severe non-typhoidal Salmonella (NTS) infection is associated with colon cancer (CC). These severe cases, however, represent only a small fraction of all NTS infections occurring in the population. To assess the overall impact of NTS infections on CC development, we performed a retrospective serological study on NTS exposure in CC patients. We observed significant positive association between the magnitude of exposure to NTS and CC risk. Furthermore, repetitive exposure to low NTS doses were shown to recapitulate the tumorigenic effect of a high NTS exposure in vivo and repetitive infection with NTS was shown to induce an increase in malignant transformation in predisposed fibroblast cells.