During the 13th Probiotics, Prebiotics and New Foods Congress, Microbiomepost.com conducted an exclusive interview with Emilia Ghelardi, professor of Microbiology and Molecular Microbiology at the University of Pisa.

The intestinal microbiota plays a key protective role against enteric pathogens, limiting their growth through the production of short-chain fatty acids, the deconjugation of bile acids, and the reduction of nutrient availability in the gut lumen. Recent evidence, however, indicates that pathogens are not only passive targets of this ecosystem, but can actively disrupt the integrity of the commensal community by competing for nutrients and producing compounds that damage or kill beneficial microbes. Most of our current knowledge derives from clinical studies, which are invaluable for describing the real-world impact of enteric infections on the gut microbiota, but are also influenced by multiple confounding factors. Animal models offer additional insight, yet are limited by interspecies differences and the holobiont concept. For this reason, in vitro models of the human gut microbiota have been increasingly proposed as preclinical tools to dissect host–microbe–pathogen interactions. In a recent work from our laboratory, we focused on Bacillus cereus, an enteric pathogen capable of causing emetic and diarrheal syndromes through the production of several toxins, and evaluated its impact on a healthy gut microbiota in vitro. Overall, available data support a bidirectional relationship in which dysbiosis favors enteric infections, while enteric pathogens themselves further alter microbiota composition, creating conditions that are more prone to recurrent or new infections. A combined strategy integrating clinical, animal and in vitro approaches is therefore needed to fully understand what happens in the intestine during infection.