Screening tests for gonorrhoea should first do no harm

We have previously reported increasing rates of gonorrhoea in a suburban sexually transmitted infection (STI) clinic population in Sydney,1 with prevalence of heterosexual gonorrhoea rising from 1.1% in 2008 to 3.0% in 2012, a similar time period to that of the study by Chow et al.2 The majority of Neisseria gonorrhoea (NG) cases (82%) were positive on culture. The remaining 18% of NG cases, positive by nucleic acid amplification testing (NAAT), were confirmed by supplementary assays targeting porA and opa genes as required by the National Testing Guidelines.3 We identified pharyngeal NG as a potentially important reservoir in heterosexual transmission, particularly with commercial sex worker exposure. Culturing NG also enabled detection of decreased susceptibility to ceftriaxone (MIC ≥ 0.03 mg/L) in 2.5% NG isolates from men who have sex with men (MSM) in this population over the same period. We concur with Chow et al2 that screening asymptomatic women in low prevalence populations may be associated with a higher false positive NG NAAT rates. However, this concern should be mitigated by guideline-recommended confirmatory supplemental testing for positive NG PCRs,3 with general practitioners being aware of these PCR test limitations. With NG prevalence continuing to increase in New South Wales,4 we advocate continued vigilance and screening of high-risk men and women, including pharyngeal swabs, where indicated, with confirmatory supplemental testing and culture ideally, for NAAT-positive NG results.