The Development of the Bacterial Flora in the Gastrointestinal Tract of Mice

Abstract

The findings to be reported in this and the following papers reveal that mice and other mammals normally harbor an extensive bacterial flora not only in the large intestine, b u t also in the stomach and small intestine. Although this flora plays an essential role in the development and well being of its host, its exact composition is not known. In fact, several of its most important and numerous components are usually overlooked in bacteriological studies because they have exacting g r o w t h requirements, and because their susceptibility to the antagouistic activity of other microbial species makes it difficult to cultivate them in vitro.We shall describe in the present paper: (a) the methods used in our laboratory for quantitative bacteriological studies of the gastrointestinal tract; and (b) the development of the gastrointestinal flora as observed in newborn mice until the time of weaning. Materials and MethodsExperimental Animals.--Extensive studies of the gastrointestinal flora have been carried out during the past 6 years with socalled Swiss mice of the NCS colony, maintained in our laboratory under the conditions described earlier (1-3); mice from other colonies, raised under conventional conditions, were also used for comparative studies.The animals were housed, and allowed to mate, in stainless steel cages, with autoclaved wood shavings as litter. The drinking water, given ad lib., was acidified with HC1 to control bacterial contamination as described earlier.In certain experiments, the same end was achieved by adding an organic silver compound in a dilution of 1 part of silver per million. The food also given ad lib. consisted either of pasteurized pellets (supplied by Dietrich and Gambrill, Frederick, Maryland) or of a semisynthetic complete diet containing 15 per cent casein (described in reference 4). It is worth emphasizing that both the pellets and the casein diets had been so treated as to eliminate all bacterial contaminants except a few spores.Preparation of Specimer~ for Bacteriological Examination.--Stool specimens were collected from mice on sterile paper between 9:00 a.m. and 10:30 a.m. Approximately 0.1 gm of stool was emulsified in 5 ml of sterile diluent (charcoal water) by 4 minutes agitation on a mechanl-

p120-catenin is essential for maintenance of barrier function and intestinal homeostasis in mice

“…For example, in human infants, the initially sterile intestine is fully colonized between 1 and 2 weeks of age, and this coincides temporally with the onset of necrotizing enterocolitis, an acute inflammatory disease that is often lethal (55,56). Notably, similar colonization rates have been reported in mice (57), and the disease progression in our mice takes place over a similar time frame. Indeed, although p120 ablation in our mice occurs well before birth, differences in villus morphology were not pronounced until approximately day 10.…”

Mechanisms of association of Candida albicans with intestinal mucosa

“…Such bacteria-yeast interactions have also been observed in patients with urinary candidosis (Marrie and Costerton,198 l). The inability of C. albicans to associate with the intestinal mucosa of untreated (control) animals in this study was probably due to the presence of the indigenous anaerobic bacteria, that are absent in neonatal or antibiotic-treated animals (Schaedler et al, 1965;Davis et al, 1973), and that inhibit the mucosal association of C. albicans by forming a dense layer of bacteria in the mucous gel, depriving the yeast cells of adhesion sites, and producing inhibitor substances (e.g., volatile fatty acids) that modify the surface properties of C. albicans or mucosal receptors (Kennedy and Volz, 1985a). The antibiotic treatments used here modified the caecal environment and reduced the total concentrations of VFA in the animals' caeca.…”

“…It has been reported that indigenous mucosaassociated bacteria reduced the association of C. albicans with the intestinal wall, and this reduced the ability of Candida to colonise the GI tract and spread systemically to visceral organs (Kennedy and Volz, 1985a and b). In infant mice that lack a complete bacterial flora, including the dense microbial populations in the mucous gel (Schaedler et al, 1965;Davis et al, 1973), C. albicans was found to associate readily with the gut wall and to pass through the mucosa to initiate systemic infection (Pope et al, 1979;Field et al, 1981). These studies also showed that Candida cells adhered to the secreting epithelium and keratinised epithelium of the stomach and the epithelial surface of the small intestine.…”

Autoinducer-2 influences interactions amongst pioneer colonizing streptococci in oral biofilms

“…AI-2 activity was not detected in non-supplemented broth from wild-type species or the luxS species. Schaedler broth is a general purpose liquid medium for the growth of fastidious aerobic and anaerobic bacteria (Schaedler et al, 1965) that has been used in the testing of oral bacteria for the production of AI-2 (Frias et al, 2001). Until now, Schaedler broth has not been supplemented with boric acid and requirement for boric acid to detect AI-2 produced by streptococci in Schaedler broth has not been shown before, to our knowledge.…”