TABLE 2.
Susceptibilities of in vitro mutants of B. fragilis to fluoroquinolones and amino acid substitutions in the A subunit of DNA gyrase
| Straina | MICb (μg/ml)
|
Amino acid substitution in GyrA | ||||
|---|---|---|---|---|---|---|
| CIP | SPA | CLI | MOX | TRO | ||
| ATCC 25285 | 4 | 1 | 0.12 | 0.25 | 0.25 | |
| Mc1 and Mc2 | 8 | 1 | 0.12 | 0.5 | 0.25 | |
| Mc3 | 32 | 8 | 1 | 2 | 2 | |
| Mc4 and Mc5 | 64 | 16 | 2 | 8 | 4 | Ser82→Phe |
| Mt1 | 4 | 1 | 0.12 | 0.25 | 2 | Ala118→Val |
| Mt2 | 8 | 8 | 0.5 | 2 | 2 | |
| Mt3 | 16 | 4 | 0.5 | 2 | 4 | Asp81→Asn |
a
Mutants Mc1 and Mc2 were selected from the parental strain ATCC 25285 on ciprofloxacin at two times the MIC. Mutant Mc3 and mutants Mc4 and Mc5 were selected from first-step mutants Mc1 and Mc2, respectively, on ciprofloxacin at two times the MIC. Mutants Mt1 through Mt3 were selected from the parental strain ATCC 25285 on trovafloxacin at two times the MIC.
b
CIP, ciprofloxacin; SPA, sparfloxacin; CLI, clinafloxacin; MOX, moxifloxacin; TRO, trovafloxacin.