EFFECT OF MANNOSE ON SALMONELLA-TYPHIMURIUM-MEDIATED LOSS OF MUCOSAL EPITHELIAL INTEGRITY IN CULTURED CHICK INTESTINAL SEGMENTS

The effect of incubating Salmonella typhimurium and S. typhimurium cel l-free extracts with isolated intestinal segments from 1-day-old chick s was evaluated using scanning electron microscopy. Incubation of segm ents with intact bacteria or with cell-free extract resulted in the lo ss of mucosal epithelial integrity after as little as 30 min incubatio n. Loss of mucosal epithelial integrity was evidenced by the complete shedding of the epithelium. The addition of 2.5% D-mannose to the incu bation medium inhibited the loss of epithelial cells, whether intestin al segments were incubated with intact bacteria or with cell-free extr act. These results indicate that S. typhimurium exerts a D-mannose-sen sitive cytotoxic effect on the mucosal epithelium of isolated intestin al segments and that the cytotoxic effector is present in cell-free ex tracts of the bacteria.