Appendix Table 1. In vitro activity of 6 antimicrobial agents against macrolide-resistant Streptococcus pyogenes phenotypes during 1999–2003

Antimicrobial*

Constitutive (n = 209)

M (n = 279)

Inducible (n = 18)

Range

MIC₅₀

MIC₉₀

Range

MIC₅₀

MIC₉₀

Range

MIC₅₀

MIC₉₀

Erythromycin

4–>512

>512

>512

1–128

8

16

1–>512

4

>512

Clindamycin

2–>512

>512

>512

≤0.03–4

0.06

1

0.125–256

0.75

128

Clarithromycin

1–>512

>512

>512

1–256

8

16

0.5–>512

2

>512

Azithromycin

4–>512

>512

>512

1–128

8

16

0.5–>512

4

>512

Tetracycline

0.06–128

32

64

≤0.03–64

0.25

0.5

0.06–64

0.5

64

Telithromycin†

0.0075–32

1

8

0.0075–2

0.5

0.5

0.003–4

0.06

0.5

*Dilution range of 0.03 to 512 μg/mL for all antimicrobial agents except telithromycin, which is 0.00375 to 64 μg/mL.

†Breakpoints for telithromycin, susceptible ≤1μg/mL, resistant ≥4 μg/mL.