Note from the British Association of Sexual Health and HIV (BASHH): This guideline complements the 2010 Health Protection Agency (HPA) document Guidance for gonorrhoea testing in England and Wales. This guideline should be read in conjunction with the BASHH United Kingdom (UK) national guideline for the management of gonorrhoea in adults 2010.
Definitions for the level of evidence (I-IV) and grade of recommendation (A-C) are provided at the end of the "Major Recommendations" field.
Major Changes in 2012 Guideline
Significant developments since the publication of the previous guideline in 2006 include:
- Nucleic acid amplification tests (NAATs) are now used in many clinical services for detecting Neisseria gonorrhoeae and widespread clinical experience has been gained with these tests.
- New NAATs with different nucleic acid targets and improved sensitivity and specificity have been developed and licensed; the Health protection Agency (HPA) has published guidance for gonorrhoea testing in England and Wales and the Health Protection Scotland (HPS) similar guidance in Scotland.
- There have been clinical reports of treatment failures using many recommended treatments for gonorrhoea and increasing concern about reduced sensitivity of N. gonorrhoeae to third generation cephalosporins.
Major New Recommendations
- NAATs are the test of choice for testing asymptomatic individuals for urethral or endocervical infection with N. gonorrhoeae.
- NAATs are the test of choice for testing rectal and pharyngeal infection in men who have sex with men (MSM).
- Positive NAATs from extragenital sites and low prevalence populations need confirmation by supplementary testing that uses a different nucleic acid target.
- The re-introduction of test of cure is recommended as part of the routine follow-up of patients treated for gonorrhoea.
- Testing by culture remains essential where infection persists after treatment and treatment failure is suspected.
No test offers 100% sensitivity and specificity and the prevalence of gonorrhoea in many genitourinary and sexual health clinics is less than 1%. The prevalence may vary between subgroups of patients even within the same clinic. The testing methodology used should give a positive predictive value (PPV) exceeding 90%. Laboratories used for testing should be appropriately accredited by a nationally approved accreditation scheme, notably by Clinical Pathology Accreditation (UK) Ltd (CPA) or equivalent.
There are two principal ways to detect N. gonorrhoeae – by detection of amplified nucleic acid and by culture. N. gonorrhoeae can also be visualized by microscopy of Gram stained specimens from the ano-genital mucosae which can be used to facilitate rapid diagnosis in symptomatic patients.
- Nucleic acid amplification tests (NAATs) are the recommended tests for urine in men, non-invasively collected samples (e.g., vulvovaginal swab) and for identifying rectal and pharyngeal infection in men-who-have-sex-with-men (MSM) (IIa, B). For endocervical and urethral specimens, NAATs offer higher sensitivity and less demanding specimen handling than culture but deny the opportunity for antimicrobial sensitivity testing.
- Culture remains a sensitive test for clinician taken genital specimens and is essential for patients with persisting symptoms or signs after treatment to exclude antimicrobial resistance.
- Microscopy of Gram-stained endocervical and urethral smears has low (40-60%) sensitivity in screening asymptomatic patients and is not recommended for routine practice.
- A culture should be taken in all cases of gonorrhoea diagnosed by NAAT's prior to antibiotics being given, if possible, so that susceptibility testing can be performed and resistant strains identified.
Recommended Sites for Testing
Mucosal sites associated with symptoms (discharge and/or pain) or signs (discharge and/or inflammation) should be tested for N. gonorrhoeae.
Current clinical practice in the United Kingdom (UK) for screening asymptomatic heterosexual individuals for gonorrhoea utilizes a single test and the sensitivity and convenience of NAATs: a first pass urine is collected from men and a vulvovaginal swab (which may be self taken) from women. Urine can be used in women but is sub-optimal. There is no data to confirm the adequacy of this approach. Culture testing in women identified the urethra as the only site of infection in 6%. Sampling the endocervix and urethra continues to be recommended when testing women by culture. There is little recent data quantifying the additional contribution of routinely taking rectal and pharyngeal specimens when screening women, although sampling should be considered at these sites where there is a history of direct exposure. There are no data on the minimum incubation period necessary to exclude infection but it is pragmatic to align it with the recommendation for chlamydia: that a test should be done when the patient presents and if the exposure was within the last two weeks, repeated two weeks after exposure.
In women, the endocervix is the principal site sampled, either directly during speculum examination or indirectly by a vulvovaginal swab. Samples taken directly from the endocervix are suitable for culture, NAATs and microscopy. Water based gel lubricants that are sterile and do not contain bacteriostatic or bactericidal additives appear not to affect cultures or NAATs for N. gonorrhoeae.
In men, the urethra is the principal site sampled, either directly from the urethral meatus or indirectly in a first pass urine sample. Samples directly taken from the urethra are suitable for microscopy, culture and NAATs. For sampling, a loop or cotton-tipped swab is introduced 1 to 2 cm into the urethral orifice. A higher sensitivity for microscopy is reported for urethral samples taken with a plastic loop compared to those taken with a cotton-tipped swab.
In women, sampling the urethra is only recommended to complement testing with endocervical culture and after hysterectomy.
Rectal testing should be dictated by symptoms and history of direct sexual exposure. The rectum can be sampled by culture and NAATs. NAATs offer significantly enhanced sensitivity compared with culture in MSM and are the test of choice in this patient population. Confirmatory testing is recommended for positive results. The use of NAATs on rectal samples may require local validation to comply with CPA accreditation. Anorectal samples from patients without symptoms may be obtained by blindly passing a moist swab 2 to 4 cm into the anal canal, using lateral pressure to try and avoid any faecal mass (IIIB). Swabs with heavy faecal contamination should be discarded. In symptomatic patients, proctoscopy may aid diagnosis and allow specimens to be obtained under direct vision. Obtaining smears under direct vision improves the low sensitivity of microscopy (IIIC) to aid immediate diagnosis.
Oropharyngeal testing should be dictated by symptoms and history of direct sexual exposure. For men, the pharynx should be sampled if the man has been the active provider of fellatio, but not if he is only the active provider of cunnilingus. Specimens are obtained by wiping a swab over the posterior pharynx, tonsils, and tonsillar crypts. Samples can be tested by culture (although sensitivity is low) and NAATs. NAATs are not approved for testing for N. gonorrhoeae in the pharynx but offer significantly enhanced sensitivity compared with culture in MSM and other high risk individuals. They are the test of choice in these patient populations and confirmatory testing is recommended for positive results. The use of NAATs on pharyngeal samples may require local validation to comply with CPA accreditation.
Urine is an easily obtained non-invasive sample and is the sample of choice when testing asymptomatic men using a NAAT. The first 15 to 30 mls of urine is collected after urine has been held for at least an hour. Urine is not suitable for culture. In women, the sensitivity of urine testing by NAATs is lower than vulvovaginal or endocervical swabs and urine is not a specimen of choice in women (IIB).
Patient-taken vulvovaginal swabs and clinician-taken endocervical swabs are equally suitable for detecting N. gonorrhoeae when tested by NAATs. Vulvovaginal swabs are the sample of choice for screening asymptomatic women for gonorrhoea.
Neisseria gonorrhoeae may infect the vaginal mucosa of prepubertal girls because the vagina is lined with columnar epithelium in pre-pubertal girls. Vaginal samples should be cultured in these circumstances in view of the implications of the diagnosis and to provide diagnostic certainty.
When a Bartholin's abscess is present, purulent material expressed from the duct may be cultured and stained for microscopy.
Ophthalmic and Systemic Sites
Ophthalmic samples are suitable for culture. Specimens are obtained after cleaning excess exudates by wiping a swab over the lower eye lid. NAATs are not licensed for this site and there is no data to validate their use on the conjunctiva.
Proving infection in patients with suspected disseminated gonococcal infection (DGI) can be difficult. The diagnosis of DGI is made on the basis of positive blood or synovial culture or, in a patient with the typical clinical syndrome and negative blood or synovial culture results, on the basis of gonococci isolated from another site. Genital and pharyngeal samples should be taken and have a higher yield in identifying the presence of N. gonorrhoeae than blood cultures (IIIC).
Factors Which Alter Tests Recommended or Sites Tested
Testing in heterosexual men and women focuses on the genital tract. Infection may be asymptomatic and all sexually active heterosexuals requesting screening for sexually transmitted infection at a genitourinary medicine clinic should receive a genital tract test for gonorrhoea. The prevalence of pharyngeal infection in patients attending genitourinary clinics in the UK is believed to be low and there is no evidence to support routine pharyngeal testing of heterosexuals who disclose oro-genital sexual activity. Data from a high-risk female population in the Netherlands show a prevalence of isolated pharyngeal infection of <0.3%. Rectal testing in women practicing anal sex is indicated in the presence of symptoms consistent with rectal infection and after sexual assault with anal penetration. The additional contribution of a rectal test to a vulvovaginal or endocervical NAAT to determine the infection status of asymptomatic women is small even in a high-risk population. A history of condom use for intercourse is not an indication to omit testing for gonorrhoea.
- Men who have sex with men
Tests should be taken from all sites (urethra, rectum, and oropharynx) potentially exposed to infection as directed by the sexual history (recommendation C). Rectal infection may be acquired by transmission from the oropharynx in the absence of penetrative anal intercourse.
- Sex workers
Test all sites potentially exposed to infection as indicated by sexual history. A history of condom use should not deter testing at exposed sites.
- 'Young' patients
Testing in post-pubertal young men and women follows that in adults. Young people may be intimidated by the prospect of invasive tests and may prefer non-invasive options when available, notably urine testing. Cultures and implementation of chain of evidence should be considered if there is prospect of legal proceedings for sexual abuse.
- Pregnant women
Screening tests as for heterosexual women.
- Women with history of hysterectomy
A urethral swab for culture offers a better yield than high vaginal culture. No comparative data was found on testing urine, urethral swab, and vaginal swabs by NAATs.
- Patients who are known contacts of gonorrhoea
Test all sites potentially exposed to infection as indicated by the sexual history. Microscopy may be worthwhile even if the patient is asymptomatic.
Recommendation for Frequency of Repeat Testing in an Asymptomatic Patient
The minimum time interval between exposure and when to test for gonorrhoea has not been determined (see above). Symptoms may develop within a few days and the incubation period for detection by culture is said to be 2 to 7 days.
Repeat testing should relate to risk rather than to a prescribed frequency. The prevalence of gonorrhoea in the general population is low but there are linked population subgroups at higher risk of infection and re-infection. The chance of contracting gonorrhoea depends largely on membership or contact with these subpopulations. A past history of gonorrhoea is a strong risk factor for re-infection. Re-infection rates of 0 to 30.8% have been reported in follow-up studies and about a third of patients with gonorrhoea in England and Wales have a history of previous infection. There is no compelling evidence to support frequent checks in sex workers, who have almost universal condom use at work. No general recommendation on the frequency of repeat testing in asymptomatic patients is suggested. Sexual health checks in relation to new risk exposures are self-evident and commended.
Recommendation for Test of Cure
Progressive creep in minimal inhibitory concentration (MIC) to cephalosporins and reported treatment failures with ceftriaxone and cefixime indicate that microbiological cure can no longer be presumed with currently recommended treatments. Test of cure is recommended following treatment for all gonococcal infections (IVC). This is to identify treatment failure, emerging resistance which is predicted to occur on the basis of the past capability/history of N. gonorrhoeae and because susceptibility results that indicate potential failure to ceftriaxone and cefixime are not yet defined.
Where resource or practical considerations require test of cure to be selective rather than universal, then the following patients should be prioritized –
- Persisting symptoms or signs
- Pharyngeal infection (all treatments are less effective at eradicating pharyngeal infection)
- Treatment with anything other than the first-line recommendations
- Pregnant women
Method and Timing of Test of Cure
There is a lack of evidence on optimal timing for test of cure and method of testing. Current opinion and pragmatic considerations suggest that where there are persisting symptoms or signs, testing with culture should be performed at least 72 hours after completion of therapy.
If asymptomatic, test with NAAT's where available followed by culture if positive. Test two weeks after completion of antibiotic therapy.
Level of Evidence
Ia Meta-analysis of randomised controlled trials
Ib At least one randomised controlled trial
IIa At least one well designed controlled study without randomisation
IIb At least one other type of well-designed quasi-experimental study
III Well designed non-experimental descriptive studies
IV Expert committee reports or opinions of respected authorities
Grading of Recommendation
- Evidence at level Ia or Ib
- Evidence at level IIa, IIb, III
- Evidence at level IV