Trends in gonorrhoea positivity by nucleic acid amplification test versus culture among Australian heterosexual men with a low prevalence of gonorrhoea, 2007-2014

Background Testing for gonorrhoea with nucleic acid amplification tests (NAATs) is not recommended in low-prevalence populations as it results in high numbers of false positive results. The aim of this study was to examine temporal trends of gonorrhoea positivity by NAAT and culture in heterosexual men in Victoria, Australia following recent increases in gonorrhoea notifications. Methods Three data sources between 2007 and 2014 were used in this study: notification data from the Victorian Department of Health, Medicare testing numbers of single chlamydia and dual NAATs performed, and electronic records on heterosexual men attending Melbourne Sexual Health Centre (MSHC). Results Notifications of gonorrhoea by NAAT (with/without culture) in heterosexual men in Victoria rose threefold from 74 in 2007 to 238 in 2014, while the number of dual NAATs ordered over the same period underwent a fivefold increase from 14 061 to 71 860. The overall proportion of NAATs that were positive for gonorrhoea in Victoria was low and fell from 0.53% in 2007 to 0.33% in 2014 (P-trend=0.002). Of the 28014 new heterosexual men attending MSHC, the gonorrhoea positivity by culture was 0.9%, and chlamydia positivity by NAAT was 8.5%. The positivity of both infections did not change over time. Conclusions These data suggest that gonorrhoea prevalence in heterosexual men is low and stable, despite annual increases in notifications. Guidelines in most countries recommend restricting testing to groups or populations with prevalence over 1%, symptomatic individuals or those at increased epidemiological risk. These data indicate gonorrhoea testing should not automatically accompany chlamydia screening in low-risk heterosexual men.