A Method for Obtaining a Pure Culture of Balantidium coli

Abstract

Balantidium coli, the ciliate of the large bowel of the pig, and not infrequently reported from man, the monkey and the guinea pig, has been grown in vitro by Walker, 1 Barrett and Yarbrough 2 and Rees. 3 The latter investigator was able to isolate single individuals and start a pure line of the organism obtained from the guinea pig. In all of these attempts, however, the medium was contaminated by various fecal bacteria and no efforts appear to have been made to develop pure cultures, although the need for such a procedure is evident.

Opportunity to attempt the sterilizing of balantidia against fecal bacteria was presented to the writer during the summer of 1929, when all of 12 individuals of Macacus rhesus, which had been under observation by Dr. C. C. Bass for a non-protozoan infection, were found to be passing cysts and trophozoites of Balantidium coli in their stools. Rectal specimens from those individuals which gave the richest yields of trophozoites were washed and concentrated in a modified Ringer's fluid and the active organisms freed of fecal debris and gross bacterial contamination.

Preliminary tests were then made with several bactericidal agents in various dilutions to determine if any could be found which were lethal to the bacteria without injuring the active balantidia. The most promising of these were acriviolet and neutral acriflavine. The washed trophozoites were placed in the following dilutions of each of these drugs and the organisms examined after 5 minutes, 10 minutes, 30 minutes and 60 minutes respectively: 1/1,000; 1/2,000; 1/4,000; 1/8,000; 1/16,000; 1/32,000; 1/64,000; and 1/128,000. In both series the dilutions of 1/8,000 or less, even for as short a period as 10 minutes were toxic to the trophozoites.