CYTOTOXICITY, ADHESION AND INVASION OF CLOSTRIDIUM-SEPTICUM IN CULTURED HUMAN EPITHELIAL-CELLS (CACO-2, HEP-2) - PATHOLOGICAL SIGNIFICANCE OF SWARM CELL-DIFFERENTIATION

Clostridium septicum NCTC 282 was cytotoxic for CACO-2 and HEp-2 cells . However, HEp-2 cells were more resistant than CACO-2 cells to C. sep ticum cytotoxin. Short motile rod forms were considerably more cytotox ic than swarming bacteria. Bacterial adhesion only occurred with HEp-2 , and short motile rod forms adhered in significantly greater numbers than swarming bacteria. Removal of bacterial flagella by mechanical sh earing had Little effect on adherence, demonstrating that these surfac e structures did not act as adhesins. Addition of a variety of monosac charides (sucrose, D-fucose, L-fucose, mannose) to HEp-2 cell monolaye rs had little effect on bacterial adhesion, although maltose effected a 50% reduction. Invasion of HEp-2 cells by C. septicum occurred with short motile rods, but not with swarming bacteria, suggesting that the initial stages of infection by this organism may be affected by the a bilities of different cell forms to adhere to and invade epithelial ce lls. Since cytotoxicity, adherence and epithelial cell invasion by C. septicum is dependent on bacterial form, differentiation of the organi sm into swarm cells in response to environmental factors will influenc e the pathogenesis of infection. (C) 1996 Academic Press