The Centers for Disease Control and Prevention (CDC) recommendations for definitive identification of N. gonorrhoeae requires that both of the following criteria are met:
Isolation from Culture with Presumptive Identification
Isolation of N. gonorrhoeae from a site (e.g., urethral, endocervical, throat, or rectal specimen) on media (usually selective) that demonstrates all of the following:
- Positive oxidase reaction
- Typical colony morphology
- Typical Gram stain morphology (gram-negative diplococci)
***AND***
Confirmation
The presumptive identification of the isolate must then be confirmed. This commonly utilizes nucleic acid probes, enzyme-substrate tests, or biochemical tests. If using serologic methods such as coagglutination or fluorescent antibody tests, they should be supplemented with additional tests to ensure accurate identification of the isolates. Carbohydrate utilization using cystine trypticase soy agar (CTA) is no longer recommended for N. gonorrhoeae due to misleading results. N. gonorrhoeae produces acid ONLY from glucose, and commercial tests are available to detect acid production.
Note on medicolegal cases:
Definitive/confirmed identification is required for medicolegal purposes, such as in cases of suspected rape or sexual abuse. In these situations, this should include isolation from culture and identifying the isolate by at least two culture confirmation tests with different principles, such as a biochemical test and nucleic acid probe. Isolates should be preserved in case additional or repeat testing is needed.
