TABLE 1.

Activities of erythromycin, clindamycin, and tetracycline against 54 erythromycin-resistant and 55 erythromycin- susceptible S. agalactiae isolates

Organisms (no. of isolates tested) and antimicrobial agent	MICa (μg/ml)
	50%	90%	Range
Erythromycin-resistant isolates (54)
Erythromycin	4	>64	1->64
Clindamycin	16	>64	0.03->64
Tetracycline	32	64	0.05-64
Erythromycin-susceptible isolates (55)
Erythromycin	0.03	0.03	0.01-0.06
Clindamycin	0.03	0.06	0.03-0.06
Tetracycline	16	32	0.01-64

^aBreakpoints from the NCCLS for resistant isolates are as follows: erythromycin and clindamycin, ≥1 μg/ml; tetracycline, ≥8 μg/ml.