Clostridia in the Gut Microbiota and Their Implication in Food Allergies and Foodborne Diseases

The gut microbiota is a fundamental component of health in humans and animals and is an important focal point for the diagnosis of several diseases. It has been reported that gut microbes are estimated to contain 100-fold more genetic potential than a human's own genome. Therefore, they can provide many functions; many of them still unknown. Clostridia are gram positive-rod shape bacteria in the phylum of Firmicutes, which play a crucial role in gut homeostasis. For example, commensal Clostridia are associated with the metabolic welfare of colonocytes by releasing butyrate as an end product of fermentation. Another important, recent finding is that elevated levels of Clostridium clusters XIVa and IV in mice lead to resistance to allergens and intestinal inflammation in experimental models. It has, also, been reported that aging affects the presence of Clostridia in the gastrointestinal tract. Some studies showed a decrease in the number of these strict anaerobes, in favour of an increase in the number of facultative anaerobes; while other studies found an increase of these bacteria in patients over 65 years. Here we discuss the presence of Clostridia in a short cohort study of elderly nursing home residents. We investigated, weekly, the proportions of Clostridia in 23 elderly patients during a 4-month period. We, also, addressed the impact of diarrheal episodes and antibiotic or probiotic treatment on the gut Clostridia structure. Finally, we identified the proportions and the main species of Clostridia present in the gut microbiota of the elderly.