Why Does Antibiotic Treatment Predispose to Clostridium difficile and Salmonella Infections?

Antibiotic treatment is a well-known risk factor for the development of Salmonella and Clostridium difficile infections. This effect has been ascribed to antibiotic-induced alterations in the gut microbiota — but what are the underlying mechanisms? In a recent study involving a murine model, researchers in California showed that antibiotic-induced alterations in gut carbohydrates promote the expansion of these enteric pathogens.

To understand growth factors for Salmonella within the gut, the researchers assessed gene expression by Salmonella typhimurium in germ-free mice and in mice colonized with a single Bacteroides species. This work, along with experiments involving mutant S. typhimurium strains, showed that the presence of the carbohydr…