Cultivation and Isolation of Gonococci

Abstract

This work was undertaken to find, if possible, a simple medium which would give uniform results and at the same time prolong the life of the gonococcus in culture. We used 15 strains of gonococci from recent cases of gonorrhea. Numerous mediums were tried for isolating gonococci. The medium used most is made as follows: Beef or veal infusion-agar is prepared containing 1.6^ agar; adjusted to a Ph of 7.6. This is divided in 100 c c quantities in Erlenmeyer flasks and sterilized. These flasks are kept as stock medium for making the plates. A flask containing the infusion-agar is heated until the agar is melted; while it is still hot (90-100 C.) 30 cc of beef serum is added and thoroughly mixed so that the serum, coagulated in small particles, is distributed evenly through the medium; this is then poured into petri dishes, covered with porous terra-cotta lids and placed in the incubator over night (about 18 hours) ; the terra-cotta lids are replaced by glass lids at the end of this time, and the plates are ready for inoculation. The type of serum used seems to have little influence?human, rabbit, sheep, and calf serum all giving about the same results. On plates that were quite moist we generally found a good growth but it is short lived. On the other hand there was a degree of dryness which appeared to inhibit growth ; if the terra-cotta lids were left on for a period longer than 24 hours, the results were not satisfactory, and if the drying with the porous lids was continued as long as 72 hours, before the inoculation was made, the growth was uncertain, scanty and short lived. Varying proportions of serum were used, but it was found that 30 c c of serum to 100 c c of the infusion-agar gave the best results. In isolating the culture of gonococcus the discharge was taken from the patient directly on a sterile platinum loop and freaked thinly over the surface of the plates. The plates were warmed to body temperature before the inoculation was made and were immediately transferred to the incubator. The colonies of gonococcus appeared