Investigation of ceftriaxone-resistant Neisseria gonorrhoeae detected in Scotland, 2018-2024

Objectives: Describe the clinical, phenotypic, and genomic characteristics of ceftriaxone-resistance Neisseria gonorrhoeae from Scotland Methods: Cases were identified in routine care. Minimum inhibitory concentrations were determined for seven antimicrobial agents. Whole genome sequencing was performed with Illumina and Oxford Nanopore Technology instruments. A phylogeny containing global ceftriaxone-resistant genomes was generated with Parsnp. A collection of ST8780 genomes was also analysed to give further context using reference based mapping with Snippy. Results: There were five cases of ceftriaxone-resistant N. gonorrhoeae detected. One case (MLST ST1903) clustered within the FC428 lineage in a returning traveller from an Asia-Pacific country. Two cases belonged to the recently described extensively drug resistant MLST ST16406, a returning traveller from an Asia-Pacific country and a sexual contact within Scotland. The final two cases were a resident of an Asia-Pacific country and a sexual contact within Scotland, both belonged to MLST ST8780. These were distinct from other publicly available ST8780 genomes suggesting a novel introduction of the mosaic penA 60.001 allele. All cases were initially treated with ceftriaxone-based regimes, four returned for test of cure and showed clearance of infection. Conclusions: As ceftriaxone resistance is increasingly identified, multiple public health interventions are required to reduce the impact of resistance on gonorrhoea treatment globally.