Colonization Resistance Induced in Mice Orogastrically Dosed with Human Faecal Homogenates from Different Donors
Conway, P. L.
- Publisher: Microbial Ecology in Health and Disease
Microbial Ecology in Health and Disease
mesheuropmc: digestive, oral, and skin physiology
Human faecal samples from various donors were assessed for the capacity to provide protection against Salmonella typhimurium both in vitro and in vivo. Faecal material was collected from four healthy human subjects. Populations of anaerobic bacteria and enterics were enumerated using selective media and the isolates screened for the capacity to inhibit the in vitro growth of S. typhimurium. Isolates with inhibitory activity against S. typhimurium were detected in two out of four subjects. These isolates accounted for 8 and 2% of the total culturable faecal population, which corresponded to 6 x 108 and 2 x 108 CFU per g, respectively. Ex-germ-free mice (Balb/C) were dosed with faecal material and then challenged with S. typhimurium. Protection against infection was monitored by enumerating the faecal levels of the pathogen. Human flora associated mice had high faecal levels of anaerobes (1010 CFU per g). Faecal levels of enterics in these animals ranged from 104 to 108 CFU per g. Animals dosed with human faecal material gained protection against gastrointestinal colonisation by S. typhimurium. In these animals, the faecal levels of Salmonella ranged from 1 x 102 to 5 x 105 CFU per g, compared with the levels of greater than 5 x 106 CFU per g in animals not previously associated with the human flora. Human faecal material containing the highest levels of inhibitory isolates provided the best protection in mice, against colonisation by S. typhimurium.Keywords: colonization resistance, germ-free.