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Developments in diagnostic techniques that demonstrate significant advantages on robust evaluation should be welcomed into clinical practice. Nucleic acid amplification tests (NAATs) are already widely used in North America and some European countries for the detection of Neisseria gonorrhoeae infection, often as a combined chlamydia/gonococcal (GC) test at little or no extra cost. There are important drivers why these tests should be more widely used—they are highly sensitive, they facilitate modernisation of service delivery in genitourinary medicine (GUM) clinics, they enable screening in community settings with specimens collected by patients and they are amenable to automated processing. Culture still remains necessary for surveillance of antimicrobial resistance, confirmatory testing and testing at non‐genital sites (rectum and pharynx).
In this issue, Ryan et al1 validate the BD Probe Tec assay and describe an algorithm using this assay as the standard test for detection of N gonorrhoeae at genital sites in a GUM clinic setting. Microscopy is still used as a rapid test, but selectively for patients with symptoms or a specific risk factor for gonorrhoea. Culture is maintained, but again used selectivity for patients with symptoms, those at higher risk of gonorrhoea (men who have sex with men, past infection with gonorrhoea or contacts of gonorrhoea) and for testing at non‐genital sites. The reported outcome of this approach is increased sensitivity of gonorrhoea detection, confirmation by culture for most infections and reduced laboratory processing of negative culture plates. The study also offers further reassurance on the specificity of GC NAATs when supported by supplementary testing, as has recently been reported in a population with low prevalence of gonorrhoea.2
Should the Sheffield algorithm be widely adopted by GUM clinics? Might alternative testing protocols be more appropriate? Could dual testing by NAAT and culture be reduced further? Screening men for urethral infection by a combined GC/chlamydia NAAT on urine with an additional urethral culture test taken from those who are sexual contacts of gonorrhoea or who have symptoms or signs of urethral discharge would seem fairly straightforward. Asymptomatic and untreated men testing positive in the NAAT would be reassessed by culture and then receive antimicrobial treatment. In women, genital tract GC infection is frequently asymptomatic. Infection may be confined to the urethra. Vaginal discharge is a common symptom, with poor sensitivity and specificity for this infection. Do cultures really need to be taken for all symptomatic women? Further debate is needed and more experience needs to be gained on the relative effectiveness of taking cultures using a “best‐guess” approach as against greater reliance on recall and reassessment. History shows that the UK was slow to implement molecular tests for the detection of genital‐tract chlamydial infection. With appropriate strategies and quality assurance, the time is surely right to move forward with GC NAATs.3