TABLE 2.
Macrolide resistance genes, phenotypes, and serotypes of erythromycin-nonsusceptible isolates
| Gene(s) | mef subclass | Phenotype | No. of isolates | MIC range (μg/ml)
|
Serotype(s) (no. of isolates) | |
|---|---|---|---|---|---|---|
| Erythromycin | Clindamycin | |||||
| mef (15 [19.7])a | mef(E) | M | 8 | 1-8 | 0.015-0.06 | 6A (1), 6B (2), 19A (1), 19F (1), 23F (1), 35F (1), NTb (1) |
| mef(I)c | M | 5 | 2-8 | 0.015-0.06 | 6A (2), 11B (1), NT (2) | |
| mefd | M | 2 | 8-16 | 0.03 | 9A (1), 13(1) | |
| erm(B) (38 [50.0]) | iMcLS | 27 | 2-≥32 | 2-≥32 | 3 (3), 6A (2), 6B (15), 14 (2), 19F (2), 35C (1), NT (2) | |
| iMcLS (NBe) | 2 | ≥32 | ≥32 | 6A (1), 6B (1) | ||
| cMLS | 9 | ≥32 | ≥32 | 6A (1), 19A (1), 19F (3), 23F (2), 35F (1), NT (1) | ||
| erm(B) + mef(E) | iMcLS (NB) | 2 | ≥32 | ≥32 | 23F (2) | |
| (23 [30.3]) | cMLS | 21 | ≥32 | 8-≥32 | 19F (4), 23F (16), NT (1) | |
a
Data in parentheses represent the number (percent) of isolates.
b
NT, nontypeable.
c
For three of these isolates, mef(I) was assigned on the basis of sequencing of an internal fragment.
d
Similarity of 99% with mef from a Bacteroides ovatus strain with GenBank accession number AJ557257.
e
NB, no blunting of inhibition zone around rokitamycin.