TABLE 2.
MIC of macrolides in the presence and absence of inducera for erythromycin-resistant strains
| Strain | MIC (μg/ml) with or without inducerb
|
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Erythromycin
|
Rokitamycin
|
Midecamycin
|
Leucomycin
|
Clarithromycinc (−) | Azithromycin (−) | Roxithromycin (−) | PCR product
|
||||||
| − | + | − | + | − | + | − | + | erm | mefE | ||||
| S. oralis SO12 | >1,024 | >1,024 | 1 | >256 | 4 | >128 | 8 | >1,024 | >1,024 | >1,024 | >1,024 | + | − |
| S. mitis SO13 | >1,024 | >1,024 | 2 | >256 | 16 | >128 | 16 | >1,024 | >1,024 | >1,024 | >1,024 | + | − |
| S. mitis E2 | 512 | 512 | 1 | 256 | 4 | >128 | 4 | >512 | >512 | >512 | >512 | + | − |
| S. oralis O14 | 512 | >512 | <0.125 | >256 | <0.063 | >128 | <0.25 | >512 | 256 | 1 | 2 | + | + |
| S. oralis E21 | 512 | >512 | 1 | 512 | 2 | >128 | 4 | >512 | 256 | 64 | 2 | + | − |
| S. mitis E3 | 512 | >128 | 8 | 16 | >128 | >128 | >128 | >256 | 64 | >512 | >512 | − | + |
| S. mitis E11 | 32 | 16 | <0.031 | 0.25 | 0.25 | 0.5 | 0.25 | 0.5 | 32 | 64 | 64 | − | − |
| S. oralis E17 | 16 | 16 | 0.25 | <0.25 | 0.125 | 0.125 | 0.125 | 0.25 | 8 | 32 | 32 | − | + |
| S. mitis E27 | 16 | 8 | <0.25 | <0.25 | <0.031 | <0.063 | <0.031 | <0.125 | 32 | >32 | >32 | − | − |
| S. oralis O24 | 8 | 8 | <0.25 | <0.25 | 0.125 | <0.063 | 0.063 | <0.125 | 4 | 32 | 16 | − | + |
| S. mitis E10 | 8 | NDc | 0.5 | ND | ND | ND | ND | ND | 8 | 16 | 16 | − | − |
| S. mitis E18 | 8 | ND | 0.25 | ND | ND | ND | ND | ND | 8 | 16 | 8 | − | − |
| S. mitis E30 | 8 | 32 | 0.125 | <0.25 | 0.25 | 0.5 | <0.25 | 0.5 | 8 | 32 | 32 | + | − |
a
The inducing concentration of erythromycin was 0.25 μg/ml.
b
−, absence of inducer; +, presence of inducer. Note that the MICs of clarithromycin, azithromycin, and roxithromycin in the presence of inducer were not determined.
c
ND, not determined.