TABLE 4.
MICs of MLS and non-MLS agentsb for M. smegmatis expressing erm(38) in trans, an erm(38) knockout mutant, and a 23S rRNA gene mutant
| Variant | Genotypea | MIC (μg/ml)
|
|||||
|---|---|---|---|---|---|---|---|
| MLS agent
|
Non-MLS agent
|
||||||
| CLNc | CLR | Q | SPM | D | RBT | ||
| MV261 (WT) | pMV261 | 32 | 1 | 64 | 8 | 128 | 0.5 |
| MVACCerm1.4 | pMV261::erm | >1,024 | >512 | 64 | >1,024 | 128 | 0.5 |
| ermKO_4 | Δermd | 4 | 0.125 | 64 | 8 | 128 | 0.5 |
| MVOTERM-1 | Δerm, pMV261::erm | >1,024 | >512 | 64 | >1,024 | 128 | 0.5 |
| CLR-1 | Δerm, rrn mutant | >1,024 | >512 | 64 | >1,024 | 128 | 0.5 |
a
pMV261::erm, erm(38) expressed in trans from pMV261 expression vector; Δerm, erm(38) knockout variant; rrn mutant, A2058→C 23S rRNA gene mutation.
b
CLN, clindamycin; CLR, clarithromycin; D, dalfopristin; Q, quinupristin; SPM, spiramycin; RBT, rifabutin.
c
MICs of clindamycin and erythromycin were identical.
d
MICs did not change for the erm mutant following 18 h of incubation either in 0.06 μg of clarithromycin/ml or in 1 μg of erythromycin/ml.