Characterization of 14 clinical isolates of N. gonorrhoeae for which erythromycin and azithromycin MICs are elevated

Strain no.A/Sa classERY MIC (μg/ml)bAZM MIC (μg/ml)c23S rRNA mutation at position 2611 (E. coli numbering system)mtr mutationdrplD mutation (L4 protein)rplV mutation (L22 protein)
20869NR/IB-0132.0-64.04.0C→T, alleles 1, 2, and 4eNo mutationNo mutationNTf
20870NR/IB-0132.0-64.04.0C→T, alleles 1, 2, and 4eNo mutationNo mutationNT
18649NR/IB-018.02.0No mutationA deletionNTNT
19255H/IB-012.02.0No mutationA deletionNTNT
19283NR/IB-014.02.0No mutationA deletionNTNT
19378NR/IB-034.02.0No mutationA deletionNo mutationNT
19398NR/IB-174.02.0No mutationA deletionNo mutationNT
19416H/IB-038.02.0No mutationA deletionNo mutationNT
19418NR/IB-018.02.0No mutationA deletionNo mutationNT
19446NR/IB-038.02.0No mutationA deletionNTNT
19486NR/IB-328.02.0No mutationA deletionNo mutationNT
19491NR/IB-038.02.0No mutationA deletionNo mutationNT
19561NR/IB-018.02.0No mutationA deletionNTNT
21631NR/IB-0116.02.0No mutationA deletionNo mutationNT
  • a A/S, auxotype-serotype; all carried a 2.6-mDa plasmid.

  • b ERY, erythromycin.

  • c AZM, azithromycin.

  • d The mtr mutation is the single-base-pair (A) deletion in the 13-bp inverted repeat in the mtrR-mtrC promoter region.

  • e GenBank accession numbers: AF450074-AF45008; C2599T for alleles 1, 2 and C2605T for allele 4 (N. gonorrhoeae numbering).

  • f NT, not tested.