A new improved medium for antibiotic susceptibility testing of N. gonorrhoeae.

In order to assess the effectiveness of the agar plate dilution method for susceptibility testing of N. gonorrhoeae, different media were used. A total of 2,210 N. gonorrhoeae strains were tested on eight different media. The best results were obtained with G.C. base medium (Difco) enriched with 0.1% Isovitalex and 1.5% lysed horse blood and by using a bacterial inoculum with the opacity of No. 1 McFarland nephelometric standard. This medium yielded constant results and 98.6% of the N. gonorrhoeae strains grew well on the control plates.