TABLE 2.
Phenotypic induction of macrolide resistance in 23 mef(E)-positive and 2 macrolide-susceptible S. pneumoniae isolates
| S. pneumoniae isolate type | n (%) | Exptl condition | Etest MIC (μg/ml)a
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ERY
|
CLR
|
AZI
|
CLI
|
TEL
|
||||||||
| MIC90 | Range | MIC90 | Range | MIC90 | Range | MIC90 | Range | MIC90 | Range | |||
| M-phenotype | 23 (92) | Before induction | 64 | 3-128 | 32 | 2-64 | 96 | 16-128 | 0.19 | 0.023-0.25 | 0.5 | 0.125-0.75 |
| After induction | 256 | 8-256 | 196 | 12-256 | 256 | 32-256 | 0.25 | 0.047-0.25 | 1 | 0.25-1.5 | ||
| Susceptible | 2 (8) | Before induction | 0.25 | 0.25 | 0.047 | 0.032-0.047 | 0.008 | 0.008 | ||||
| After induction | 0.25 | 0.25 | 0.047 | 0.047 | 0.008 | 0.008 | ||||||
a
ERY, erythromycin; CLR, clarithromycin; AZI, azithromycin; CLI, clindamycin; TEL, telithromycin.