TABLE 3.
Macrolide and tetracycline determinants of resistance in different clones of Streptococcus pyogenes with the MLSB resistance phenotype
| Clone | No. of isolates
|
Erythromycin
|
Tetracycline
|
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Total | ermB | ermA | tetM | tetO | int/xis | MIC50 (μg/ml) | MIC90 (μg/ml) | MIC50 (μg/ml) | MIC90 (μg/ml) | |
| emm11/T11/ST403 | 463 | 462a | 1 | 462 | 0 | 462 | >64 | >64 | >4 | >4 |
| emm28/T28/ST52, bacitracin resistant | 115 | 115 | 0 | 0 | 0 | 0 | >64 | >64 | <0.5 | <0.5 |
| emm28/T28/ST52, bacitracin susceptible | 33 | 32 | 1 | 31b | 0 | 22 | >64 | >64 | >4 | >4 |
| emm22/T12/ST46 | 62 | 24 | 38c | 10 | 0 | 10 | 4 | >64 | <0.5 | >4 |
| emm77/T28/ST63 | 24 | 1d | 23 | 0 | 24 | 1 | 4 | 8 | >4 | >4 |
| emm73/T13/ST331 | 13 | 3 | 10 | 2 | 0 | 2 | 8 | >64 | <0.5 | >4 |
| emm94/TB3264/ST89 | 8 | 1 | 7 | 8 | 0 | 8 | 8 | >64 | >4 | >4 |
| emm89/TB3264/ST101 | 4 | 4 | 0 | 0 | 0 | 0 | >64 | >64 | <0.5 | <0.5 |
| emm58/TNT/ST19 | 3 | 3 | 0 | 0 | 0 | 0 | >64 | >64 | <0.5 | <0.5 |
| emm12/T12/ST36 | 3 | 3 | 0 | 2 | 0 | 1 | >64 | >64 | >4 | >4 |
| emm6/T6/ST37 | 3 | 3 | 0 | 1 | 0 | 1 | >64 | >64 | <0.5 | >4 |
| emm2/T2/ST55 | 2e | 1 | 0 | 1 | 0 | 1 | >64 | >64 | >0.5 | >4 |
| emm4/T4/ST39 | 2 | 1 | 1 | 1 | 0 | 1 | 4 | >64 | <0.5 | >4 |
| emm81/TB3264/ST117 | 1 | 1 | 0 | 1 | 1 | 1 | >64 | >64 | >4 | >4 |
| emm68/TB3264,3/ST247 | 1 | 0 | 0 | 1 | 0 | 1 | 2 | >4 | ||
| emm75/T8,25/ST150 | 1 | 1 | 0 | 1 | 0 | 1 | >64 | >4 | ||
| emm102/T4/ST376 | 1 | 0 | 0 | 1 | 0 | 1 | >64 | 2 | ||
a
Two isolates were ermB+ and mef+.
b
One isolate was ermA+, tetM negative, and int/xis negative, and another was ermB+, tetM negative, and int/xis negative.
c
One isolate was ermA+ and mef+.
d
One isolate was ermB+, mef+, and int/xis+.
e
One isolate was ermB negative, ermA negative, mef negative, tetM negative, and int/xis negative.