Mechanisms associated with the bacterial populations in the small intestine of cystic fibrosis mice.

Abstract

Abnormal mucus secretions characterize cystic fibrosis (CF). In a mouse model of CF, the pathology manifested in the small intestine is typified by a dehydrated, more acidic environment of the lumen. It is likely that this creates a more favorable environment for bacteria to colonize and proliferate within the small intestine. In this study, the types of cultivable aerobic bacteria of the small intestine were determined by analyzing colony morphology on a nutrient media. Bacterial colony morphologies with differences in abundance between CF and WT mice were isolated and used for proliferation, adherence and antimicrobial activity experiments. A difference was observed in proliferation in only one of five bacterial species in small intestinal supernatant. The adherence experiments only showed a difference between WT and CF small intestinal supernatants in Escherichia coli, and only one of four isolates showed any detectable adherence. In addition the antimicrobial activity of soluble compounds was determined by a radial diffusion assay. This assay revealed no difference between the CF mice and the WT mice in all but one of the isolates suggesting that the antimicrobial activity within the small intestine lumen is similar. Also the amount of IgA in the lumen was determined through an ELISA, and a nearly three fold increase was found in the CF mice. These data suggest proliferation, and soluble antimicrobial compounds might not be critical for controlling abundance of the bacteria that were isolated in the small intestine of CF and WT mice.