What are we missing? Data from the Gonorrhoea Undetected Resistance Laboratory Study (GURLS)

Increasing ceftriaxone-resistant Neisseria gonorrhoeae is of public health concern. A cluster of ceftriaxone-resistant N. gonorrhoeae was identified in 2022, which was linked to heterosexuals from the Asia-Pacific region who were studying at UK universities. The possibility of further transmission within and beyond this network was of concern, particularly as not all gonococcal cases have a positive culture for antimicrobial susceptibility testing to be performed. We, therefore, undertook a case finding exercise using an N. gonorrhoeae penA real-time PCR to identify undetected transmission of ceftriaxone-resistant strains. The PCR detects penA-60.001, which is the most common gonococcal ceftriaxone-resistance mechanism. The aim of this Gonorrhoea Undetected Resistance Laboratory Study was to estimate the prevalence of undetected ceftriaxone-resistant N. gonorrhoeae in England.

Sexually transmitted infection surveillance data (2017-2021) was combined with university data on student country of origin to identify sexual health services in English university towns with the highest number of gonorrhoea cases among those of Asian ethnicity born in selected countries of the Asia-Pacific region. Residual N. gonorrhoeae-positive molecular specimens from women (as a proxy for heterosexual behaviour) aged 18-30 years were sent to the UK Health Security Agency (UKHSA) for testing.

Between February 2023 and March 2024, 921 specimens meeting the inclusion criteria were received, of which 661 were reconfirmed as N. gonorrhoeae. Of these, one was positive on the penA PCR, indicating ceftriaxone resistance; this specimen came from a previously identified case, therefore no 'undetected' cases were identified.

This case-finding exercise provided reassurance that ceftriaxone-resistant N. gonorrhoeae in England is currently adequately detected through the existing UKHSA-enhanced surveillance activities. The current penA PCR is a useful tool in the fight to keep gonorrhoea a treatable infection; however, it requires expansion as it does not currently detect all penA alleles responsible for ceftriaxone resistance.