Table 2.

MICs of fluoroquinolones for VGS and mutations in topoisomerases

StrainOriginaMIC (μg/ml) ofb:Amino acid (nucleotides) at indicated positionc
GyrAGyrB 494ParCParE
SM103335T16 (4)2 (2)0.5S (TCC)E (GAA)S (TCA)S (AGT)D (GAT)D (GAT)E (GAG)
SMB8HQ32 (2)4 (2)1ND— (GAC)— (GAA)
SMB9HQ128 (8)16 (8)1NDND
SMB11H32 (2)4 (1)1— (TCA)NDNDND
SMB12C32 (2)4 (1)1— (TCA)NDNDND
SMB13C64 (2)16 (4)2NDI (ATC)
SMB14H128 (4)64 (4)2F (TTC)— (GAC)K (AAG)
SO102922T32 (4)2 (2)0.5S (TCC)E (GAA)T (ACT)S (TCT)D (GAT)D (GAT)E (GAA)
SOB3H64 (4)4 (2)0.5S (TCA)R (AGA)— (GAG)
SOB4C64 (8)4 (2)0.5— (TCG)— (GAG)— (AGT)NDND
SOB5HQ128 (16)16 (8)1— (GAC)— (GAG)
SOB6HQ64 (4)8 (2)1S (TCA)N (AAT)— (GAC)
SOB7H128 (4)8 (2)1H (CAT)
SOB8HQ128 (4)8 (2)1Y (TAT)NDND
SOB9HQ128 (4)16 (4)1NDF (TTT)NDND
SOB14HQ256 (4)16 (4)2Y (TAT)— (GAC)
SOB10HQ256 (8)64 (4)16Y (TAC)S (TCA)— (AGT)N (AAT)NDND
SOB11HQ256 (4)128 (2)64— (TCA)G (GGA)F (TTT)— (GAG)
SOB12H256 (2)128 (2)32Y (TAC)F (TTT)— (GAC)
SOB13H256 (2)128 (2)64Y (TAC)— (AGT)N (AAT)— (GAC)
SS55128T32 (4)2 (2)0.5S (TCT)E (GAA)NDS (AGC)D (GAT)NDND
SSB1H64 (2)4 (1)0.5— (TCC)ND— (AGT)Y (TAT)NDND
SSB2HQ128 (16)16 (8)0.5— (TCC)NDNDND
  • a H, hospitalized patient not treated with FQs; HQ, hospitalized patient treated with FQs; C, nonhospitalized, untreated control subject.

  • b NOR, norfloxacin; CIP, ciprofloxacin; SPX, sparfloxacin. Values in parentheses are the MIC fold decreases in the presence of 10 μg of reserpine per ml.

  • c Amino acid position corresponds to that of amino acid numbering of topoisomerase subunits fromS. pneumoniae (2, 12, 17). —, no change with respect to type strain; ND, not determined.