The growth of Treponema hyodysenteriae and other porcine intestinal spirochaetes in a liquid medium

A new simple method for the preparation of a liquid medium containing rabbit serum for the propagation of Treponema hyodysenteriae and other porcine intestinal spirochaetes is described. The medium, when dispensed in shallow layers and sealed under 10 per cent CO2 in nitrogen, had a redox potential not greater than − 125mV and an initial pH of about 6-9 when buffered with bicarbonate. Growth of T hyodysenteriae developed more rapidly and viable counts reached higher levels at 42°C than at 37°C. Viable counts increased at least 10,000-fold after two to five days’ incubation, depending on the temperature. Growth could be initiated from small inocula that failed to produce colonies on blood agar. Using a I per cent inoculum, the medium supported the growth of two strains of T hyodysenteriae through 10 serial passages.