“Resistant gonorrhoea: east meets west”
“In 2016 and 2018, two treatment failures of ceftriaxone and azithromycin, used in combination, were reported in the UK in men who contracted gonococcal infections in Asia,1,2 once again suggesting that antimicrobial resistance of Neisseria gonorrhoeae is spreading. These treatment failures indicate the potentially waning efficacy and usefulness of this combination, which is currently recommended as the first-line therapy. Surveillance of antimicrobial resistance is paramount if resistance patterns of these and other antimicrobials are to be recognised in a timely manner that enables meaningful intervention and prevention of the spread of resistant organisms.
Antimicrobial susceptibility testing (phenotyping) for antimicrobial resistance is considered the gold-standard test. There are some key limitations to the more commonly used methods of genotyping, such as N gonorrhoeae multi-antigen sequence typing (NG-MAST) and multilocus sequence typing (MLST), which indicate associated antimicrobial resistance determinants but do not directly identify antimicrobial resistance. The genotypes of N gonorrhoeae strains that are identified by use of these methods, which include antimicrobial resistance determinants, often do not correlate directly with the mean inhibitory concentrations of antimicrobials against these strains.
In their Article in The Lancet Infectious Diseases, Simon Harris and colleagues3 used whole genome sequencing (WGS) for comprehensive genetic analyses of more than 1000 Neisseria gonorrhoeaestrains that were isolated in 2013 in 20 European countries that participated in the European Gonococcal Antimicrobial Surveillance Programme (Euro-GASP). As expected, NG-MAST genogroups (designated from the closely related NG-MAST sequence types) fit the WGS phylogeny relatively well; however, separation into clades (the branches of the WGS phylogeny trees) avoided separation of clinically important, phylogenetically related isolates while also excluding phylogenetically unrelated (less relevant) isolates. WGS therefore maintains the breadth of analysis that is necessary to identify known antimicrobial resistance determinants and can also identify new antimicrobial resistance determinants. MLST and NG-MAST, although sensitive in their association with known antimicrobial resistance determinants, can be non-specific.”
Read more: The Lancet Infectious Diseases