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