Table 2.

The FIC indexes of the combination of GA, MG, and the β-lactam antibiotics against S. aureus ATCC 25923 and 43300.

Bacterial Strains	Compounds	MIC		Combinded Compounds (μg/mL)	MIC		The Lowest FIC Indexes
		Alone (μg/mL)	Combined (μg/mL)		Alone (μg/mL)	Combinded (μg/mL)
MSSA (S. aureus ATCC 25923)	GA	200	6.25	Ampicillin	0.125	0.125	1.03	IND *
			6.25	Amoxicillin	0.25	0.25	1.03	IND *
			6.25	Cloxacillin	0.25	0.25	1.03	IND *
			6.25	Penicillin G	0.063	0.063	1.03	IND *
	MG	1600	50	Ampicillin	0.125	0.125	1.03	IND *
			50	Amoxicillin	0.25	0.25	1.03	IND *
			50	Cloxacillin	0.25	0.25	1.03	IND *
			50	Penicillin G	0.063	0.063	1.03	IND *
	MG	1600	800	GA	200	25	0.63	ADD *
MRSA (S. aureus ATCC 43300)	GA	400	100	Ampicillin	62.5	15.625	0.5	ADD *
			100	Amoxicillin	62.5	15.625	0.5	ADD *
			200	Cloxacillin	0.5	0.25	1	IND *
			200	Penicillin G	62.5	7.813	0.63	ADD *
	MG	1600	100	Ampicillin	62.5	15.625	0.313	SYN *
			200	Amoxicillin	62.5	15.625	0.375	SYN *
			100	Cloxacillin	0.5	0.5	1.06	IND *
			200	Penicillin G	62.5	15.625	0.375	SYN *
	MG	1600	800	GA	400	50	0.63	ADD *

* ADD: additive effect, IND: indifferent effect, SYN: synergistic effect.