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Presumptive Laboratory Identification: Neisseria gonorrhoeae

According to the Centers for Disease Control (CDC) recommendations, the presumptive identification of N. gonorrhoeae can be made if ONE of the following criteria is met:
1. Direct Gram Stain from Symptomatic MALES Only
In a symptomatic male, intracellular gram-negative diplococci (GNDC) observed in the direct Gram stain of urethral discharge is considered diagnostic for gonococcal disease. The characteristic GNDC with adjacent sides flattened (coffee beans) are visible inside polymorphonuclear leukocytes (PMNs).
In women, there are other normal vaginal and rectal flora that can resemble Neisseria species. For this reason, viewing typical intracellular GNDC in a direct Gram stain of endocervical exudate from a symptomatic female must be supported by growth in culture or detection by a nonculture method, such as a molecular assay.
2. Culture, Positive Oxidase, and Demonstration of Typical Morphology
The growth of GNDC from a urethral or endocervical specimen on selective media, such as modified Thayer-Martin (MTM), that demonstrates ALL of the following:
  • Positive oxidase reaction
  • Typical colony morphology
  • Typical Gram stain morphology
3. Detection by a Nonculture Test
The detection of N. gonorrhoeae by a nonculture assay, such as antigen detection, nonamplified DNA probe, or nucleic acid amplification tests (NAATs). Both amplified and nonamplified tests are suitable for screening, but amplified methods are more sensitive. NAATs are commonly used by high volume laboratories.