Where have all the susceptible gonococci gone? A historical review of changes in MIC distribution over the past 75 years
Abstract Background Does the emergence of antimicrobial resistance in Neisseria gonorrhoeae include an elimination of highly susceptible strains or does it merely involve a stretching of the MIC distribution? If it was the former this would be important to know as it would increase the probability that the loss of susceptibility is irreversible.Methods We conducted a historical analysis based on a literature review of changes of N. gonorrhoeae MIC distribution over the past 75 years for 3 antimicrobials (benzylpenicillin, ceftriaxone and azithromycin) in five countries (Denmark, Japan, South Africa, the United Kingdom and the United States).Results Changes in MIC distribution were most marked for benzylpenicillin and showed evidence of a right shifting of MIC distribution that occurred in up to 3 stages and was associated with a reduction/elimination of susceptible strains in all countries. In the case of ceftriaxone and azithromycin, right shifting was also found in all countries but the extent of right shifting varied and the evidence for the elimination of susceptible strains was more mixed.Conclusions Further research is required to assess why some populations have undergone a stage 3 as opposed to a stage 1 or 2 transition, with the greater loss of susceptible isolates that this involves. If differential antimicrobial consumption was found to be responsible, then this would provide additional impetus to promote antimicrobial stewardship.