Intestinal bacterial flora and host defense mechanisms.

The protective mechanisms of intestinal bacterial flora against exogenous infections will be discussed in this paper. Experimental data on protective function of Escherichia coli, Enterococcus faecalis and Bacteroides distasonis comprising intestinal flora against oral infection of Shigella flexneri which causes localized infection are presented. Furthermore, the present investigation deals with non-specific defense mechanism which indicate that protective activity of intestinal flora against parenteral infection of Salmonella typhimurium mainly depend upon the larger number of functional kupffer cells in conventional mice than in that of their germfree counterparts.