Antagonistic Effect of Intestinal Bacteria from the Microflora of Holoxenic (Conventional) Piglets, Against Clostridium Perfringens in the Digestive Tract of Gnotoxenic Mice and Gnotoxenic Piglets

Antagonistic effect of piglet microflora against Clostridium perfringens was studied in germfree mice, to isolate bacterial strains responsible for this colonization resistance. The 1:100 dilution of the feces of a 2 day-old conventional piglet, given per os to germfree mice already harboring C. perfringens, led to the elimination of C. perfringens. From this piglet flora, 8 bacterial strains were selected, belonging to the genera Bacteroides, Clostridium, Eubacterium, Bifidobacterium, Lactobacillus and a strain belonging to the class of Mollicutes. When the 8 strains were given to germfree mice 3 days after C. perfringens inoculation, they led to rapid elimination of C. perfringens from feces. Sixteen other mixtures of 2 to 7 strains were similarly tested, but none was able to fully antagonize C. perfringens. When the 8 strains were given per os to germfree piglets after C. perfringens inoculation, they led to the rapid elimination of C. perfringens from pig feces, and to a quick recovery from diarrhea. This study led to the identification of a simplified fraction of gut microflora, able to exert a barrier effect against C. perfringens comparable to the entire flora of the piglet. This study suggests that gnotoxenic mice can be a suitable model for simplifying the flora responsible for a given effect in another host, animal or human.