O22 Molecular Characterisation of Six Ceftriaxone Resistant Neisseria Gonorrhoeae Identified in UK Residents Between December 2021 and February 2022

Introduction Between December 2021 and February 2022 six cases of ceftriaxone resistant gonorrhoea were identified in different regions of the UK. Most but not all, of these cases had links to travel from the Asia Pacific region. Whole genome sequencing was used to investigate the relationship of these cases to each other and to other international strains. Methods Neisseria gonorrhoeae isolates from all cases were tested for phenotypic susceptibility using gradient MIC strips (Biomerieux) and EUCAST breakpoints at the National reference laboratory. Genomic DNA was extracted using the Qiasymphony DSP DNA mini kit (Qiagen) and Illumina sequencing performed by Central Sequencing Laboratory (UKHSA) with analysis performed in PathogenWatch. Results Five of the six cases belonged to MLST ST8123 and carried the penA 60.001 allele associated with ceftriaxone resistance but the strains were not identical (Table 1). The sixth case belonged to MLST ST1901 which carried a penA allele with three of the five single nucleotide polymorphisms associated with cephalosporin resistance in penA allele 60.001 (Table 1). Discussion The ST8123 lineage has been commonly reported in China but not within the UK or Europe. This, coupled with reports of sustained transmission of the globally disseminated ceftriaxone-resistant FC428 clone associated with the penA 60.001 allele within China, supports that the FC428-related strains are more likely to have resulted from independent importation events with some limited onward transmission in the UK. The ST1901 lineage is disseminated within the UK and globally and can show multi-drug resistance but is more commonly associated with cefixime resistance and ceftriaxone susceptibility.