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Table 2 In vitro activity of ciprofloxacin against S. pneumoniae with mutations in the parC gene only.

From: Characterization of the quinolone resistant determining regions in clinical isolates of pneumococci collected in Canada

  Ciprofloxacin Minimum Inhibitory Concentration (mg/L)
Number of Isolates
Substitution 0.12 0.25 0.5 1 2 4 8 16 32 64 Total
None 1 6 919 1,863 523 37 2 2 0 1 3,354
Asp-78 0 0 0 0 4 2 0 0 0 0 6
Asp-83 0 0 0 2 19 30 5 0 0 0 56
Lys-137 0 1 176 391 137 16 1 0 0 0 722
Arg-95 0 1 2 2 0 1 0 0 0 0 6
Ser-52 0 0 1 3 4 1 0 0 0 0 9
Ser-79 0 0 0 1 82 84 33 5 2 2 209
Other* 0 0 3 6 7 1 0 0 0 0 17
Tyr-129 0 0 0 3 3 1 0 0 0 0 7
  1. *Mutations at other sites include: Ala-63 (1), Val-66 (2), Met-85 (1), Asn-91 (2) Glu-99 (1), Glu-100 (1), Gly-106 (1), Ser-107 (1), Met-108 (1), Ala-115 (2), Tyr-118 (1), Arg-122 (1), Leu-130 (1), Glu-135 (1), Thr-138 (1), Ala-158 (1). Of these, two (one with Asn-91-Asp mutation, and one with Ala-115-Pro mutation) had ciprofloxacin MICs of 4 mg/L, and one (Thr-138-Ile) had a levofloxacin MIC of 2 mg/L. All others had MIC to ciprofloxacin of < 4 mg/L, to levofloxacin of < 2 mg/L, and to moxifloxacin of < 0.5 mg/L)