Tetracycline resistance of Neisseria gonorrhoeae in Russia, 2015–2017

The objective of this study was to estimate the tetracycline resistance level in the modern population of Neisseria gonorrhoeae in the Russian Federation, where this drug was removed from the treatment regimen for gonococcal infections in 2003. A total of 401 isolates collected between 2015 and 2017 were analyzed for genetic markers (chromosomal porB, rpsJ and mtrR gene mutations and the plasmid-located tetM gene) involved in tetracycline resistance. Antibiotic susceptibility testing revealed that 19% of the strains were tetracycline resistant (MIC > 1 mg/L) and that 10% of the strains had intermediate susceptibility (0.5 8 mg/L). One N. gonorrhoeae isolate was found to carry a defective tetM gene with an AG deletion at position 1239–1240, а new stop codon was introduced that caused a defect in TetM protein synthesis and decrease in the tetracycline resistance. Phylogenetic trees constructed using N. gonorrhoeae NG-MAST and tetM loci were compared. Complex relationship was observed between the N. gonorrhoeae sequence type and the tetM plasmid type. Partial recovery of N. gonorrhoeae tetracycline susceptibility was observed relative to the proportion of isolates with resistance detected ten years ago (75%). However, the current levels of tetracycline resistance still preclude the renewed use of these drugs for gonococcal infection therapy. •29% of N. gonorrhoeae isolates obtained in Russia were found to be non-susceptible to tetracycline.•Plasmid tetM genes both of American and Dutch types were identified.•Simultaneous presence of chromosomal mutations in N. gonorrhoeae led to MIC 1.47 mg/L (geometric mean value).•Acquisition of a plasmid-encoded tetM gene significantly changed tetracycline resistance level (MIC > 8 mg/L).•One N. gonorrhoeae isolate carrying a defective tetM gene with an AG deletion was found.