Identification of the Gonococcus from Cultures and the Effect of Certain Animal Sera on the Fermentations of the Gonococcus

Abstract

Identification of suspicious organisms from gonococcus primary cultures is important especially when taken from [female][female]. Various oxi-dase-positive, gram-negative organisms often appear in these cultures and they are microscopically indistinguishable from gonococci. Among organisms which may most often be confused with gonococci are Neisseria catarrhalis, Micro-coccus flavus, certain gram-negative, oxidase-positive sta-phylococci, streptococci and coccobacilli. The following cultural characteristics are used in identifying the gonococcus: typical macroscopic and microscopic morphology, absence of growth on plain agar or at room temp., no hemolysis of 5% washed horse blood-cell agar and clear-cut sugar fermentation tests. To avoid false fermentation results, the sugar medium must not be enriched vith normal horse, beef or sheep serum since in the presence of these sera the gonococcus produces acid in the maltose as well as in the glucose tube. Suitable enrichments for fermentation medium are 5% normal human, rabbit or guinea-pig serum, 20% ascitic fluid or 5% fractionally sterilized soluble starch. Starch-sugar medium is prepd. as follows: to 75 ml. of 0.3% semi-solid proteose peptone or veal infusion agar add 20 ml. of warm sterile 25% soluble starch, 21/2 ml. of 0.04% Bacto-phenol-red, 21/2 ml. of 20% sugar and 0.2 ml. of 15% Na2HPO4. Sugars used are glucose, maltose and levulose.