Background
In most clinical settings, screening for Neisseria gonorrhoeae (NG) is done by nucleic acid amplification testing (NAAT), together with NAAT for Chlamydia trachomatis (CT). This testing is sensitive and remains the recommended method for NG screening.
Recently, due to a concerning strain of gonorrhea found in Massachusetts, MDPH is now recommending culture in addition to NAAT for symptomatic individuals.1 This guide is to aid clinicians in culture collection but does not replace instructions provided by a clinician’s healthcare organization or laboratory.
1. Contact your microbiology lab or lab liaison to confirm which collection kit or supplies should be used for gonorrhea culture collection.
For example, a non-nutritive swab transport system may be used for culture collection (e.g. Amies agar gel or liquid). These swabs may maintain gonococcal viability for up to 24 hours in ambient temperatures.
Important note: Do not use NG/CT NAAT collection kits for culture. Sample preservative found in NAAT collection kits is different than the transport media used for culture collection.
2. Collect samples from patients suspected of having gonorrhea.
Gonorrhea can cause infection at urogenital sites as well as extragenital sites. NG/CT NAAT should be collected for all sexually exposed sites.
If patient is symptomatic, collect two swabs for every symptomatic site – one for NAAT and one for culture – using swabs usually provided in the collection kits. While certain NAAT collection platforms are approved for self-collection, culture is only approved for collection by a clinician.
Yield from gonococcal culture may be improved by:
- obtaining the gonorrhea culture swab first. In practice, this may not be feasible, or you may choose to collect swabs simultaneously for NAAT and culture.
- increasing the contact time between the swab and the mucosal surface being sampled. You may need a minimum of 10-15 seconds of contact, similar to the way NAAT is collected.
Important note: If a patient has urinary symptoms involving the penis, a urethral meatal swab for culture can be performed on the verge of the urethral opening (tip of the penis) or from urethral discharge. Gonorrhea can also be cultured from urine if the specimen is received and processed promptly (within hours of collection). Rule out gonorrhea, in addition to other pathogens should be specified on the urine culture lab order.
3. Ensure culture samples arrive to the microbiology lab as soon as possible, within 24 hours.
Yield may be improved the sooner the specimen is received. Arrange an extra lab pick up as needed.
Important note: Do not refrigerate gonorrhea culture samples – samples are best kept at room temperature before and during transport to the lab and should not be left outside in cold weather pending pick up.