SUBSTITUTES IN CULTURE MEDIA

The various media were prepared as follows: A 1 % suspension of liver extract powder was made in 100 ml of distilled water, thoroughly mixed, filtered through absorbent cotton and then through filter paper. The clear brownish filtrate was sterilized by passage through a Seitz filter and stored in the ice chest until used. Sterilized citrated horse blood was hemolized by freezing. The proteose agar base was autoclaved in 100 ml amounts (4.5 g Difco Bacto Proteose No. 3 Agar in 100 ml of distilled water), after which sterile glucose solution was added to a concentration of 1%,. The agar was cooled to 45 C and liver extract and citrated hemolized horse blood were mixed into the agar base and plates were poured. Five strains of Neis8eria gonorrhoeae were examined. Table 1 shows the results concerning the size of the colonies grown in the liver extract and in hemolized horse blood. The two enrichments were used alone and combined in various amounts with the base media and are compared with colonies grown in the base sugar agar alone, with the addition of 2 mg % of glutamine and with rabbit-blood chocolate agar. Depending on the amount of hemolized horse blood or liver extract added to the base agar media the cultures grow more or less luxuriantly. Two mg % glutamine and 5 % rabbit chocolate blood give equal results but are less effective than horse blood and liver extract. The best result in the growth for all strains of Neisseria gonorrhoeae are obtained when 25 ml of 1 % aqueous liver extract and 5 ml citrated hemolized horse blood are added to 100 ml of the proteose sugar agar base