Table 1.

In vitro susceptibility of 26 isolates of Pythium insidiosum to macrolides and tetracycline antibiotics

Antimicrobial agent	MIC range (geometric mean) (μg/ml) by CLSI techniquea
	Visual reading		Colorimetric reading (MTT)
	MIC-1	MIC-2	MIC-3	MIC-4
Tetracyclines
Doxycycline	0.5–8 (1.75)	0.125–1 (0.35)	0.5–8 (2.75)	0.125–0.5 (0.30)
Minocycline	0.125–2 (0.39)	0.06–0.5 (0.08)	0.125–2 (0.70)	0.06–0.5 (0.09)
Oxytetracycline	2–32 (7.38)	1–2 (1.57)	2–32 (11.01)	0.5–2 (1.41)
Tetracycline	2–32 (5.96)	0.5–2.0 (1.2)	2–32 (8.90)	1–2 (1.3)
Macrolides
Azithromycin	2–32 (4.57)	0.5–2 (1.11)	2–32 (6.29)	0.5–2 (1.3)
Clarithromycin	0.5–8 (1.53)	0.125–1 (0.49)	0.5–8 (2.22)	0.25–2 (0.57)
Erythromycin	2–32 (7.58)	0.5–4 (1.61)	2–32 (12.25)	0.5–4 (1.5)

^aMIC-1 and MIC-3 are the lowest concentrations of drug that inhibit growth (100% growth inhibition). MIC-2 and MIC-4 are the drug concentrations that result in prominent reduction in growth (50% growth inhibition) compared to growth of a the drug-free control.