TABLE 1.

Activities of two ketolides, four macrolides, and two ansamycins against B. pertussis and B. parapertussis

Organism	No. of strains	Antimicrobial agent	MIC (μg/ml)a
			Range	50%	90%
B. pertussis	51	HMR 3004	0.008–0.03	0.015	0.03
	52	HMR 3647	0.004–0.06	0.015	0.03
	40	Azithromycin	0.008–0.06	0.03	0.06
	37	Clarithromycin	0.015–0.125	0.06	0.06
	34	Erythromycin A	0.03–0.06	0.03	0.06
	36	Roxithromycin	0.03–0.25	0.06	0.125
	34	Rifampin	0.25–2.0	0.5	1.0
	34	Rifapentine	1.0–4.0	1.0	2.0
B. parapertussis	34	HMR 3004	0.25–0.5	0.25	0.25
	31	HMR 3647	0.125–0.5	0.125	0.25
	34	Azithromycin	0.06–0.25	0.06	0.06
	32	Clarithromycin	0.25–2.0	0.5	0.5
	34	Erythromycin A	0.5	0.5	0.5
	34	Roxithromycin	0.5–1.0	0.5	0.5
	34	Rifampin	2.0–4.0	2.0	2.0
	34	Rifapentine	8.0	8.0	8.0

^a50% and 90%, MIC₅₀ and MIC₉₀, respectively.