Table 2.

Relationship between amino acid substitutions in GyrA and ParC and antimicrobial susceptibilities of N. gonorrhoeae to various fluoroquinolones and other antibiotics

Amino acid substitution(s)No. of isolatesMean MIC (μg/ml) of antibioticsa:
GyrAParCSIFXHSR-903GFLXGPFXSPFXMOFXTVFX
Wild typeWild type200.0020.0020.0060.0070.0050.010.009
A67SWild type10.0040.0040.0160.0080.0160.0160.016
A75SWild type50.0090.0090.0190.0160.0160.0280.044
A84PWild type10.0040.0010.0160.0080.0160.0310.016
S91FWild type210.025 (13×)0.021 (11×)0.052 (9×)0.093 (13×)0.09 (18×)0.088 (9×)0.14 (16×)
S91CWild type10.0010.0020.0080.0080.0080.0160.016
D95GWild type80.0080.0090.0350.0330.0590.0630.055
D95NWild type50.0090.0070.0310.0250.0470.0570.041
S91F-D95GWild type10.0630.0310.50.50.510.5
S91YR116H10.0160.0160.0630.0630.1250.1250.125
S91FA92G10.0310.0310.0630.250.1250.1250.5
S91FA86N40.020.0140.0710.190.190.1250.75
S91FS88P-E91G10.0080.0160.0630.250.250.0630.5
S91F-D95NE91G10.130.0630.52110.5
S91F-D95NS88P90.0890.0720.60.720.691.20.99
S91F-D95NS87I-S88P10.250.518448
S91F-D95NS88P-E91K20.250.526646
S91F-D95NS88P-E91G10.1250.2512421
S91F-D95NS88P-E91Q10.1250.06310.510.50.125
Mean MIC (μg/ml) of antibioticsa
PUFXCPFXLVFXPZFXNFLXPCGIPMCTRXCFIXTCAZMSPCM
0.0080.0070.0120.0160.0280.230.110.0080.010.690.177.6
0.0080.0160.0310.0630.1250.0160.0630.0020.0080.0630.0638
0.0250.0310.0690.0690.25NS0.250.061 (8×)0.031 (3×)1.30.5 (3×)7.2
0.0160.0160.0310.0630.1250.0630.0630.0040.0040.0630.1258
0.22 (28×)0.24 (34×)0.34 (28×)0.48 (30×)1.6 (57×)1.1 (5×)0.41 (4×)0.092 (12×)0.074 (7×)0.710.197.8
0.0160.0080.0160.0310.0630.0310.0310.0040.00410.0638
0.0510.0290.0710.0710.20.0670.0590.0120.0070.140.08611
0.0630.0520.0880.110.350.0880.130.0070.0090.250.17.2
0.250.50.5120.1250.0630.0080.0080.50.254
0.1250.1250.250.50.50.250.0630.063 (8×)0.0080.250.0638
0.250.250.5121 (4×)0.5 (5×)0.063 (8×)0.063 (6×)10.258
0.50.220.3811.80.75 (3×)0.190.079 (10×)0.055 (6×)0.880.0638
0.250.250.250.510.50.250.063 (8×)0.063 (6×)0.50.1258
0.522240.250.250.0160.0160.50.258
1.41.83.969.80.78 (3×)0.28 (3×)0.056 (7×)0.063 (6×)0.640.119.3
816816160.50.250.063 (8×)0.063 (6×)0.50.1258
812816161 (4×)0.190.094 (12×)0.063 (6×)0.310.0638
441616160.50.250.031 (4×)0.031 (3×)0.50.0638
224880.0630.1250.0080.031 (3×)0.50.0638
  • a SIFX, sitafloxacin; GFLX, gatifloxacin; GPFX, grepafloxacin; SPFX, sparfloxacin; MOFX, moxifloxacin; TVFX, trovafloxacin; PUFX, prulifloxacin; CPFX, ciprofloxacin; LVFX, levofloxacin; PZFX, pazufloxacin; NFLX, norfloxacin; PCG, penicillin G; IPM, imipenem; CTRX, ceftriaxone; CFIX, cefixime; TC, tetracycline; AZM, azithromycin; SPCM, spectinomycin. Numbers in parentheses indicate fold change compared with wild type, and for nonfluoroquinolones numbers are shown when threefold or more. NS, data not shown because all strains were PPNG.