TABLE 1.
Macrolide resistance phenotype in 85 clinical isolates of erythromycin-resistant S. pneumoniae by the ECDD test and correlations with clindamycin susceptibility and erythromycin resistance genes
| Phenotype of macrolide resistance | No. (%) of strains | Clindamycin susceptibility (MIC [μg/ml])a of strains
|
No. of strains with the following gene:
|
||||||
|---|---|---|---|---|---|---|---|---|---|
| Without induction
|
After inductionb
|
||||||||
| Range | 50% | 90% | Range | 50% | 90% | erm(AM) | mef(E) | ||
| cMLS | 65 (76.5) | 8–>128 | 64 | >128 | 16–>128 | >128 | >128 | 65 | |
| M | 20 (23.5) | 0.03–0.12 | 0.03 | 0.12 | 0.03–0.12 | 0.03 | 0.12 | 20 | |
a
50% and 90%, MICs at which 50 and 90% of isolates were inhibited, respectively.
b
Induction was performed by pregrowth in 0.05 μg of erythromycin per ml.