Jolinda de Korne-Elenbaas 1,2, Sylvia M Bruisten 1,3, Alje P van Dam 1,2
1. Public Health Laboratory, Infectious Diseases, Amsterdam, the Netherlands; 2. Amsterdam UMC, Infectious Diseases, Amsterdam, the Netherlands; 3. Amsterdam UMC, Amsterdam Infection & Immunity Institute (AI& II), Amsterdam, the Netherlands
Objectives Neisseria gonorrhoeae (Ng) is developing resistance against extended-spectrum cephalosporins, such as ceftriaxone. Previous studies have shown associations between certain sequence types (ST) and reduced susceptibility to ceftriaxone. Here, ceftriaxone reduced susceptible (RS) and susceptible Ng strains from Amsterdam were genetically characterized to identify genetic variations associated with ceftriaxone RS.
Methods All 82 Ng strains isolated from visitors of the STI outpatient clinic in Amsterdam between 2014-2019 which had a ceftriaxone Minimum Inhibitory Concentration (MIC) ≥0.094 were whole genome sequenced. Also, 239 strains with MIC<0.094 were sequenced as a representation of the Amsterdam gonococcal population. All strains were typed according to the Multi Locus Sequence Typing (MLST) scheme, known resistance mutations were characterized and clusters were identified with a core-SNP phylogenetic tree.
Results Regarding RS strains from 2014-2016, 41% were MLST 7827 and 38% MLST 1901 containing the mosaic penA gene and porB G121K/A121N mutations associated with ceftriaxone RS. Regarding RS strains from 2017-2019, 88% were MLST 7827 and 6% MLST 1901. MLST 7827 strains showed strong genetic clustering in the phylogenetic tree and contained a non-mosaic penA gene with a A501V mutation and porB G121K/A121D mutations. MLST 7827 was not found among 96 susceptible strains from 2014-2016 and only 5% of the susceptible strains from 2017-2019 belonged to this ST. PorB G121/A121 mutations were not found in MLST 7827 strains with MIC≤0.016.
Conclusion The ceftriaxone RS associated Ng clone MLST 7827 has emerged and spread in Amsterdam in recent years. PorB G121/A121 mutations were found in all MLST 7827 strains with MIC>0.016 but not in MLST 7827 strains with ceftriaxone MIC≤0.016. This indicates that porB mutations play an important role in the ceftriaxone resistance mechanisms. Co-presence of penA mosaicism and/or mutations in RS strains indicates a multifactorial mechanism of resistance.
34 IUSTI Congress - European Congres on Sexually transmitted Infections and HIV/AIDS
TAMING THE TIDE of STIs & HIV
Bucharest, September 3-5,