Volume 197 - Issue 6
Screening with nucleic acid amplification tests for gonorrhoea in men who have sex with men
Authors: Miranda Sherley, Karina J Kennedy and Sarah J Martin
Med J Aust 2012; 197 (6): 332. || doi: 10.5694/mja12.10090
Published online: 17 September 2012
Published online: 17 September 2012
To the Editor: Australian gonorrhoea infection rates are rising.1 Infection spreads through various sexual practices, and extragenital infections are commonly asymptomatic.2 Nucleic acid amplification tests (NAATs) provide rapid, sensitive testing, regardless of the site involved or presence or absence of symptoms.3,4 There have therefore been calls for a change to NAAT-based screening for high-risk groups, including men who have sex with men (MSM).5 Limitations include ...
To the Editor: Australian gonorrhoea infection rates are rising.1 Infection spreads through various sexual practices, and extragenital infections are commonly asymptomatic.2 Nucleic acid amplification tests (NAATs) provide rapid, sensitive testing, regardless of the site involved or presence or absence of symptoms.3,4 There have therefore been calls for a change to NAAT-based screening for high-risk groups, including men who have sex with men (MSM).5 Limitations include false-positive and false-negative results due to molecular variation and lack of susceptibility data.
In 2011, the Canberra Sexual Health Centre (CSHC) changed routine screening for asymptomatic MSM from microbiological tests of the pharynx, NAAT of the urine and microbiological tests plus NAAT of the rectum, to NAAT of all three sites. Individuals with symptoms of gonorrhoea and their sexual contacts were offered microbiological testing and NAAT before presumptive treatment. The reference laboratory (ACT Pathology) had changed to a more automated gonorrhoea-NAAT (cobas 4800 CT/NG Test [Roche]) and felt this approach would improve workflow without increasing costs.
Seventy-three NAAT-positive cases of gonorrhoea in MSM were notified by CSHC in 2011, of which 37 were symptomatic and 36 asymptomatic. Ten asymptomatic cases were NAAT-positive and pharyngeal culture-negative, and would not have been diagnosed before the introduction of pharyngeal NAAT.
Fifty-eight of the 73 NAAT-positive cases were sent for microbiological testing, and 39/58 were confirmed as gonorrhoea. Symptomatic infections were significantly more likely than asymptomatic infections to have a positive microbiological culture result (27/33; 12/25, respectively) (P = 0.0074, using the one-tailed Fisher’s exact test). Sixteen NAAT-positive, culture-negative cases were high-risk (symptomatic, NAAT-positive from more than one site, sexual contact with a person who was gonorrhoea-positive, three or more sexual contacts in the past 3 months, a previous history of gonorrhoea and recent sexual contact outside Australia).
NAAT-positive pharyngeal infections were less likely than infections at other sites to be symptomatic (pharynx, 2/25; other sites, 21/32; P = 0.0006) or culturable (pharynx, 4/16; other sites, 20/23; P < 0.0001) (single-site infections with microbiological testing of the same site, one-tailed Fisher’s exact test).
Multisite Neisseria gonorrhoeae NAAT offers a sensitive, rapid and convenient method for diagnosing gonorrhoea in asymptomatic MSM. Appropriate protocols ensure that antimicrobial susceptibility data are obtained, and that assessment of risk factors is made in NAAT-positive, culture-negative individuals to identify the potential for false-positive results.
Competing interests
No relevant disclosures.
References
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- Hook EW, Handsfield HH. Gonococcal infections in the adult. In: Holms K, Sparling P, Stamm W, et al, editors. Sexually transmitted diseases. 4th ed. New York: McGraw Hill, 2008: 627-646. 0_CBBEHGAA
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- Cook RL, Hutchison SL, Østergaard L, et al. Systematic review: noninvasive testing for Chlamydia trachomatis and Neisseria gonorrhoeae. Ann Int Med 2005; 142: 914-925. 0_i1142874
- Fairley CK, Chen MY, Bradshaw CS, Tabrizi SN. Is it time to move to nucleic acid amplification tests screening for pharyngeal and rectal gonorrhoea in men who have sex with men to improve gonorrhoea control? Sex Health 2011; 8: 9-11. 0_i1142876