TABLE 1.

Susceptibility of S. agalactiae clinical strains to MLS antibiotics

Antimicrobial agent	MIC (mg/liter)b for:
	18 clini-cal strains studied	Control strains
		Suscepti-ble strain	MLSBia strain at:		MLSBca strain
			24 h	48 h
14-membered macrolides
Erythromycin	0.1–1	0.02	4	>512	>512
Clarithromycin	0.1–0.5	0.005	2	>512	>512
Dirithromycin	2–16	0.1	32	>512	>512
Roxithromycin	0.5–4	0.05	8	>512	>512
Ketolide HMR 3647	0.1–0.2	0.02	0.005	0.02	0.1
15-membered macrolides
Azithromycin	1–4	0.1	64	>512	>512
16-membered macrolides
Spiramycin	0.1–0.2	0.2	4	4	>512
Josamycin	0.1–0.2	0.2	2	4	8
Lincosamides
Lincomycin	0.02–0.1	0.1	0.5	256	256
Clindamycin	0.005–0.02	0.005	0.2	32	128
Streptogramins
Pristinamycin	0.1–0.2	0.2	0.2	0.2	0.1
Pristinamycin II	0.2–1	0.5	0.5	1	0.2
Pristinamycin I	1–4	2	4	4	8

^aMLS_Bi, MLS_B inducible phenotype; MLS_Bc, MLS_B constitutive phenotype. 

^bAll data except those for the MLS_Bi resistant strain were read at 24 h.