TABLE 4.

Effect of pH on the susceptibilities of M. pneumoniae to macrolides

pH (no. of strains tested)	MIC50 (μg/ml) (range)
	Azithromycin	Clarithromycin	Dirithromycin	Erythromycin
6.9 (45)	0.03 (0.05–0.06)	0.03 (0.015–0.03)	0.25 (0.25–0.5)	0.25 (0.12–0.25)
7.1 (45)	0.015 (0.007–0.015)	0.03 (0.015–0.06)	0.25 (0.12–0.5)	0.06 (0.03–0.12)
7.5 (22)	0.002 (0.002–0.007)	0.015 (0.007–0.015)	0.03 (0.015–0.12)	0.015 (0.007–0.03)
7.8 (45)	0.001 (0.0005–0.001)	0.004 (0.002–0.007)	0.007 (≤0.004–0.007)	0.015 (≤0.015–0.03)