In Vitro Antistaphylococcal Effects of Embelia schimperi Extracts and Their Component Embelin with Oxacillin and Tetracycline

Table 1

In vitro inhibitory activity of Embelia schimperi ethanol extracts in combination with oxacillin against S. aureus.

	MICs (g/mL)		MICs of oxacillin in combination with listed extracts concentrations (μg/mL)
Extract/strain	Extract	Ox	+256 g/mL		+128 μg/mL		+64 μg/mL		+32 μg/mL		+16 μg/mL
			MIC	ΣFIC	MIC	ΣFIC	MIC	ΣFIC	MIC	ΣFIC	MIC	ΣFIC
Seed
ATCC 43300	341.33	32	0.21	0.757	12.04	0.751	32	1.188	32	1.094	32	1.047
MdRSA3	341.33	64	3	0.797	32.17	0.878	64	1.188	64	1.094	64	1.047
Leaves + twigs
ATCC 29213	256	0.5	0.01	1.000	0.17	0.844	0.25	0.750	0.25	0.625	0.25	0.563
ATCC 33591	256	341.33	1	1.003	2	0.506	341.33	1.250	341.33	1.125	341.33	1.063
MdRSA2	256	106.67	1	1.009	1	0.509	106.67	1.250	106.67	1.125	106.67	1.063
MRSA4	128	1.5	x	x	0.02	1.010	0.03	0.517	1.42	1.194	1.42	1.069
TRSA1	128	0.5	x	x	0.01	1.020	0.16	0.812	0.25	0.750	0.5	1.125
TRSA2	170.67	1	0.01	1.510	0.02	0.766	0.26	0.630	0.58	0.771	0.83	0.927

MIC: minimum inhibitory concentration expressed as an average from three independent experiments, each performed in triplicate; Ox: oxacillin; ATCC: American type culture collection; MRSA: methicillin-resistant S. aureus; TRSA: tetracycline-resistant S. aureus; MdRSA: multidrug-resistant S. aureus; x: not calculated; ΣFIC: sum of fractional inhibitory concentrations: the combinatory effect is evaluated as follows: synergy if ΣFIC ≤0.5; additive if ΣFIC >0.5 and ≤1; indifferent if ΣFIC >1 and <2; and antagonistic if ΣFIC ≥2.