Gonorrhea is a common sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. It can infect both men and women and is spread through unprotected vaginal, oral, or anal sex with an infected partner. Gonorrhea can cause infections in the genitals, rectum, and throat. Obgyns have several methods for testing patients for gonorrhea.
Signs and Symptoms
Many people with gonorrhea are asymptomatic, especially women. When symptoms do occur, they can include:
- Thick, cloudy, or bloody discharge from the penis or vagina
- Pain or burning sensation when urinating
- Itching or irritation inside the penis
- Painful or swollen testicles
- Vaginal bleeding between periods
- Sore throat (gonococcal pharyngitis)
- Anal itching, soreness, bleeding, or discharge (anal gonorrhea)
Symptoms usually appear within 2 to 14 days after exposure. However, some people remain asymptomatic for months. Untreated gonorrhea can lead to serious complications like pelvic inflammatory disease, infertility, and increased risk of HIV transmission.
Who Should be Tested
The CDC recommends gonorrhea testing for:
- Women younger than 25 years
- Women over 25 years with risk factors like new or multiple sex partners
- Pregnant women
- Women with inconsistent condom use
- Women who exchange sex for money or drugs
- People with HIV
- Men who have sex with men
Testing is also recommended for anyone with gonorrhea symptoms or whose partner has tested positive for gonorrhea.
Nucleic Acid Amplification Tests (NAATs)
NAATs are the most commonly used diagnostic tests for gonorrhea. These tests detect the genetic material of the N. gonorrhoeae bacterium. NAATs can be performed on urine samples or swab samples collected from infected sites like the cervix, urethra, rectum, or throat.
Advantages of NAATs:
- High sensitivity – detect 86-100% of gonorrhea cases
- High specificity – false positives are rare
- Results within 1-2 days
- Non-invasive sample collection
- Tests multiple infections from one sample (gonorrhea, chlamydia, trichomoniasis)
Limitations:
- Expensive equipment required
- Laboratory expertise needed
- Does not determine antibiotic susceptibility
Types of NAATs
- PCR (polymerase chain reaction):amplifies DNA to detect gonorrhea genetic material
- TMA (transcription-mediated amplification): amplifies RNA to detect gonorrhea RNA
- SDA (strand displacement amplification): amplifies DNA at constant temperature to detect gonorrhea DNA
Gram Stain
Gram staining can be done on urethral or cervical discharge samples from symptomatic patients. It involves staining discharge smears with dyes to visualize N. gonorrhoeae diplococci bacteria under a microscope.
Advantages:
- Rapid results within minutes
- Confirms presence of gram-negative diplococci
- Low cost
- Minimal equipment needed
Limitations:
- Low sensitivity – misses 30-50% of infections
- Low specificity – cannot differentiate between N. gonorrhoeae and other Neisseria species
- Requires experienced microscopist
- Only useful for symptomatic males with discharge
- Does not provide antibiotic susceptibility information
Due to poor sensitivity, a negative gram stain does not rule out gonorrhea. Positive results should be confirmed with culture or NAAT.
Gonorrhea Culture
Culturing N. gonorrhoeae bacteria is the gold standard method for diagnosing gonorrhea. Samples are collected from the cervix, urethra, rectum, or throat and incubated on selective culture media.
Advantages of culture:
- 100% specificity – confirms diagnosis
- Determines antibiotic susceptibility of bacteria
- Allows monitoring of resistance trends
Disadvantages:
- Only 50-70% sensitive
- Requires strict transport and storage conditions to maintain viability of bacteria
- Slow growth – Results in 24-72 hours
- Laborious process requiring experienced staff
Due to poor sensitivity, a negative culture cannot exclude gonorrhea. Positive culture is diagnostic but NAAT is preferred for routine screening due to faster results.
How Obgyns Choose a Test
Obgyns consider the following factors when choosing a gonorrhea test:
- Symptoms – Gram stain or culture for symptomatic patients; NAAT for asymptomatic
- Timeframe – NAAT for faster results; culture if antibiotic resistance is a concern
- Specimen type – Urine or swabs depending on site of infection
- Test availability – NAAT preferred but gram stain or culture if NAAT unavailable
- Cost – Gram stain is cheapest option
- Sensitivity required – NAAT has highest sensitivity for screening
NAAT on urine or cervical/urethral swabs is the preferred test for most patients. However, culture or gram stain may be done for symptomatic patients, when antibiotic resistance is suspected, or when NAAT is unavailable.
How Often Should Testing be Done
The CDC recommends the following gonorrhea testing frequency:
- Annual testing for high-risk individuals such as those aged below 25, people living with HIV, men who have sex with men, etc.
- For lower-risk individuals, testing whenever they have a new sex partner or if their partner has tested positive.
- Retesting 3 months after treatment to confirm cure, especially for those at high risk of re-infection.
- Screening all pregnant women at first prenatal visit.
- Retesting pregnant women at time of delivery if at ongoing risk.
More frequent gonorrhea testing such as every 3-6 months may be warranted for very high-risk groups.
Dual Gonorrhea/Chlamydia Testing
Obgyns often test for both gonorrhea and chlamydia together as co-infections are common. NAATs from one urine or swab sample can detect both infections. If positive for either infection, the patient’s sex partners should also be treated to prevent reinfection.
When to Test for Other STIs
If a patient tests positive for gonorrhea, additional STI testing may be warranted including tests for:
- Chlamydia
- Trichomoniasis
- HIV
- Syphilis
- Hepatitis
This more extensive testing helps identify co-infections that also require treatment.
Summary
Key points about gonorrhea testing in Obgyn practice:
- NAAT on urine or swabs is preferred for routine screening due to high sensitivity and specificity.
- Gram stain or culture may be done for symptomatic patients.
- High-risk individuals should be tested annually; lower risk if new partner.
- Retest pregnant women and positives at follow up.
- Also test for chlamydia, trich, HIV, syphilis if gonorrhea positive.
- Choose test based on symptoms, cost, lab availability, need for antibiotic resistance data.
A combination of NAAT screening along with selective use of culture and gram stain allows for accurate diagnosis of gonorrhea, guiding appropriate antibiotic treatment to cure infection and prevent complications.
References
- Centers for Disease Control and Prevention. (2021). Gonorrhea – CDC Fact Sheet. https://www.cdc.gov/std/gonorrhea/stdfact-gonorrhea.htm
- Hicks, L.A., Clements, N., Boeras, D.I., Peeling, R.W., Vickerman, P. (2022). A scoping review of point-of-care tests for the diagnosis and management of curable sexually transmitted infections in adults. PLoS ONE, 17(7): e0269973. https://doi.org/10.1371/journal.pone.0269973
- Unemo, M. and Jensen, J.S. (2017). Antimicrobial-resistant sexually transmitted infections: gonorrhoea and Mycoplasma genitalium. Nature Reviews Urology, 14(3), 139-152. https://www.nature.com/articles/nrurol.2016.268
- U.S. Preventive Services Task Force. (2021). Screening for Gonorrhea: US Preventive Services Task Force Recommendation Statement. JAMA, 326(10):880–887. doi:10.1001/jama.2021.13731
- Workowski KA, Bachmann LH, Chan PA, et al. (2021). Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep 2021;70(No. RR-4):1–187. DOI: http://dx.doi.org/10.15585/mmwr.rr7004a1