TABLE 1.
Characteristics of selected fluoroquinolone-resistant mutants of M. pneumoniae
| Reference strain, selection method, or selected mutantc | MIC (μg/ml) ofa:
|
Amino acid change(s) in QRDR ofb:
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| CIP | SPX | LVX | MXF | GEM | GAT | GyrA | GyrB | ParC | ParE | |
| FH | 2 | 0.12 | 0.5 | 0.12 | 0.12 | 0.12 | None | None | None | None |
| SPX selection | ||||||||||
| On agar | ||||||||||
| IIPSA | 8 | 1 | 2 | 0.5 | 1 | NDd | —e | — | G81C | — |
| IIPSC1 | 8 | 1 | 2 | 0.5 | 1 | ND | — | — | D87Y | — |
| IIIPSD1 | 8 | 2 | 2 | 0.5 | 1 | ND | — | — | D87N | — |
| IIIPSD3 | 8 | 1 | 4 | 0.5 | 1 | ND | — | — | A83V | — |
| In broth | ||||||||||
| S5A | 4 | 1 | 1 | 0.5 | 0.5 | ND | — | — | D87N | — |
| S7A | 16 | 2 | 2 | 1 | 4 | ND | — | E483G | D87N | — |
| S10A | 32 | 8 | 16 | 4 | 8 | ND | — | D443N | D87N | — |
| LVX selection | ||||||||||
| On agar | ||||||||||
| IPLA | 8 | 1 | 2 | 0.5 | 0.5 | ND | D99N | — | — | — |
| In broth | ||||||||||
| L7A | 8 | 1 | 4 | 2 | 1 | ND | D99N | — | — | P449S |
| L15A | 32 | 16 | 16 | 8 | 4 | ND | D99N | — | D87N | P449S |
| MXF selection | ||||||||||
| On agar | ||||||||||
| IPMB | 2 | 0.25 | 1 | 0.25 | 0.5 | ND | — | E483G | — | — |
| IIPMB | 8 | 1 | 2 | 1 | 2 | ND | — | E483G | D87N | — |
| In broth | ||||||||||
| M5A | 16 | 8 | 16 | 2 | 4 | ND | — | D443N | D87N | — |
| M15A | 16 | 16 | 16 | 8 | 4 | ND | — | D443N, R464K | D87N | — |
| GEM selection | ||||||||||
| On agar | ||||||||||
| IIIPGB | 8 | 1 | 2 | 0.25 | 1 | ND | — | — | D87G | — |
| In broth | ||||||||||
| G5A | 8 | 1 | 2 | 1 | 1 | ND | D99N | — | — | — |
| G7A | 16 | 16 | 16 | 2 | 4 | ND | D99N | — | D87G | P449S |
| CIP selection (in broth only) | ||||||||||
| C7A | 16 | 2 | 2 | 2 | 4 | ND | — | E483G | G81C | — |
| C7B | 8 | 2 | 2 | 1 | 1 | ND | — | — | G81C | — |
| GAT selection (in broth only) | ||||||||||
| Ga2A | 16 | 2 | 4 | 1 | 8 | 2 | — | E483G | G81C | — |
CIP, ciprofloxacin; SPX, sparfloxacin; LVX, levofloxacin; MXF, moxifloxacin; GEM, gemifloxacin; GAT, gatifloxacin.
M. pneumoniae positions GyrA 99, GyrB 443, 464, and 483, ParC 81, 83, and 87, and ParE 449 correspond to E. coli coordinates GyrA 83, GyrB 426, 447, and 466, ParC 78, 80, and 84, and ParE 439.
M. pneumoniae FH is the parental strain. Agar-selected mutants are designated by a prefix corresponding to the selection step (I, II, or III) followed by the initial of the species (P) and of the selector fluoroquinolone (C, ciprofloxacin; S, sparfloxacin; L, levofloxacin; M, moxifloxacin; G, gemifloxacin; Ga, gatifloxacin). Broth-selected mutants are designated by the initial of the selector fluoroquinolone, followed by the passage number. Fifteen passages were performed for each antibiotic. For passages 5, 7, 10, and 15, two of the five clones subcultured were studied except with gatifloxacin, for which passage 2 was also studied. When both clones from one passage were identical, only one clone is represented in this table. For both agar and broth methods, only clones with significantly increased MICs and QRDR mutations are shown. See footnote a for three-letter drug abbreviations.
ND, not determined.
—, identical to the reference strain.