Table 2

Neisseria gonorrhoeae strains with different cefixime MICs and ceftriaxone MICs and containing different resistance determinants used as recipients in transformation experiments of full-length penA gene from F89

StrainMLST STaNG-MAST STbMIC (μg/ml)cGenotype
CefiximeCeftriaxonepenAdmtrRepenBfponAg
WHO FNewST3303<0.016e<0.002epenA XV (WT)WThWTWT
WHO MST7367ST3304<0.0160.016epenA II (A345a)A-delYesL421P
WHO KST7363ST14240.50.064penA X (Mosaic)A-delYesL421P
35/02ST7363ST3260.50.125penA XXVIII (Mosaic)A-delYesL421P
WHO LST1590ST14220.250.125penA VII (A501V)A-delYesL421P
  • a MLST, multilocus sequencing typing (29).

  • b NG-MAST, Neisseria gonorrhoeae multiantigen sequence typing (44).

  • c The Etest method reads also half-MIC steps; however, in accordance with the interpretation of the agar dilution method described by the Clinical Laboratory and Standards Institute (CLSI) (9), only whole-MIC steps are given. MICs of <0.002 μg/ml and <0.016 μg/ml were calculated as 0.001 μg/ml and 0.008 μg/ml, respectively, in the MIC ratios in Fig. 2.

  • d penA mosaic allele encodes a mosaic penicillin-binding protein 2 (PBP 2) that causes a decreased susceptibility to extended-spectrum cephalosporins (ESCs) (21, 27, 36, 41, 43, 58).

  • e A-del, a characteristic single-nucleotide (A) deletion in the inverted repeat of the promoter region of mtrR that causes overexpression of the MtrCDE efflux pump, resulting in a further decreased susceptibility to ESCs (21, 27, 41, 58).

  • f Yes, the presence of the alterations of amino acids 101 and 102 in porin PorB (penB determinant) that cause a decreased intake of ESCs and, accordingly, a further decreased susceptibility to ESCs (21, 27, 41, 58).

  • g The alteration of amino acid 421 in PBP 1 (encoded by ponA) causes decreased susceptibility to penicillins (21, 34, 58).

  • h WT, wild type.