Studies on the pathogenesis of swine dysentery. II. Search for a cytotoxin in spirochetal broth cultures and colon content.

Broth cultures of Treponema hyodysenteriae and colonic content from pigs with swine dysentery were tested for cytotoxicity in cell cultures, erythrocyte suspensions and in ligated segments of pig colon. Live cells of T. hyodysenteriae attached to the surface of cells in all cultures tested but did not penetrate them nor cause morphologic change detectable by light microscopy. Only live T. hyodysenteriae caused erythrolysis. Broth cultures or colonic content sterilized by filtration or by disruption with ultrasound had no visible effect on the cell cultures, erythrocyte suspensions or the mucosa of ligated colonic segments.