A recent Microbiome study identified a protective role of Enterocloster clostridioformis against Salmonella enterocolitis in germ-free mice. With rising drug resistance and severe infection outcomes researchers from the University of Cambridge including Virginia Pedicord and Benjamin Beresford-Jones found that E. clostridioformis enhances gut defenses by activating protective epithelial responses and increasing anti-inflammatory immune cells. Monocolonization of germ-free mice revealed that this bacterium upregulates resistin-like molecule β and cell cycle pathways while boosting regulatory T cells reducing tissue damage and improving survival against Salmonella Typhimurium infection.

Non-typhoidal salmonellosis (NTS) is a major global health concern causing millions of infections and deaths annually with rising antimicrobial resistance worsening outcomes. The gut microbiota plays a crucial role in colonization resistance against Salmonella competing for nutrients producing inhibitory substances and modulating host immune responses. Beyond colonization resistance commensal microbes can also influence pathogen virulence and enhance host defense mechanisms. In this study we identified Enterocloster clostridioformis as a key player in protective responses against Salmonella enterocolitis in mice promoting epithelial cell resilience and increasing regulatory T cells potentially reducing infection severity.

Mice infected with Salmonella Typhimurium (S.Tm) typically develop systemic disease rather than acute gut inflammation seen in human NTS. Antibiotic pretreatment can induce an inflammatory diarrheal response mimicking human Salmonella enterocolitis but yielded inconsistent infection susceptibility in SPF mice. In contrast germ-free (GF) mice were highly sensitive showing rapid weight loss and complete mortality at low pathogen doses. To identify protective microbe host interactions we screened 18 gut-derived commensal bacteria in GF mice assessing their impact on infection severity. No monocolonized mice showed disease symptoms before infection highlighting potential protective roles of specific commensals.

These findings highlight how beneficial gut bacteria can help defend against harmful pathogens and may inspire new treatment approaches. They also offer insights into gut diseases like inflammatory bowel disease and irritable bowel syndrome.

Source: https://www.med.cam.ac.uk/news/microbiome-good-gut-bacteria-may-protect-against-salmonella-infection