Antimicrobial resistance in Neisseria gonorrhoeae has developed to each of the agents that have been recommended for gonorrhea therapy.1 As a result, a well-standardized laboratory method to monitor the susceptibilities of gonococcal isolates has been recommended by the National Committee for Clinical Laboratory Standards (NCCLS). The NCCLS recently completed a multicenter study to standardize disk diffusion (and agar dilution) susceptibility tests for N. gonorrhoeae and to establish interpretive criteria and quality-control guidelines.2 The recommended test medium is GC base agar with a defined "XV-like" supplement. Control organisms are N. gonorrhoeae ATCC 49226 (CDC F-18), N. gonorrhoeae WHO V, and Staphy- lococcus aureus ATCC 25923.
Interpretive criteria based on expected treatment failure rates for single-agent therapy with penicillin, tetracycline, spectinomycin, or ceftriaxone have been selected. Resistance to penicillin is defined as a zone diameter of 26 mm (10-U disk), corresponding to a minimum inhibitory concentration (MIC) of 2 Mg/mL. Strains producing beta-lactamase
Disk Diffusion Antimicrobial Susceptibility Testing of Neisseria gonorrhoeae. Arch Dermatol. 1990;126(5):577-578. doi:10.1001/archderm.1990.01670290019002