Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans, Staphylococcus aureus, and Candida spp.

Table 2 Minimum microbicidal concentration values of isolated essential oils, and synergistic and additive combinations of Cymbopogon schoenanthus and Pelargonium graveolens essential oils against Staphylococcus aureus

Combination	Individual MMC values (%)				Combined concentrations (%)		FICI	MMC reduction		Effect
	LE		GE		LE	GE		LE	GE
C. + P.	4		4		2	0.5	0.62	2 ×	8 ×	Additive
C. + P.					2	0.25	0.56	2 ×	16 ×	Additive
C. + P.					2	0.12	0.53	2 ×	33 ×	Additive
C. + P.					1	0.06	0.26	4 ×	66 ×	Synergistic

C.: Cymbopogon schoenanthus; FICI: Fractional inhibitory concentration index; GE: Pelargonium graveolens; LE: Cymbopogon schoenanthus; MMC: Minimum microbicidal concentration; P.: Pelargonium graveolens.