Effect of Eugenol against Streptococcus agalactiae and Synergistic Interaction with Biologically Produced Silver Nanoparticles

Table 2

In vitro synergistic effect of eugenol and biological silver nanoparticles on Streptococcus agalactiae growth.

GBS strains	MIC^a			FICI^d	Effect
	Eugenol^b (%)	AgNPbio^c (µM)	Eugenol/AgNPbio
50	0.5	125	0.06/15.62	0.25	Synergism
72	0.125	125	0.03/31.25	0.5	Synergism
80	0.25	125	0.06/0.49	0.25	Synergism
89	0.25	125	0.03/7.8	0.19	Synergism
115	0.25	125	0.03/31.25	0.38	Synergism
121	0.125	125	0.03/3.9	0.281	Synergism
ATCC 13813	0.25	125	0.03/15.62	0.25	Synergism

^aMIC: minimum inhibitory concentration. ^bMIC of eugenol used alone. ^cMIC of silver nanoparticle used alone. ^dFICI: fractional inhibitory concentrations index were calculated according to Yadav et al. [35] and classified as follows: synergistic if FIC ≤0.5, additive if FIC >0.5 and ≤1.0, indifferent if FIC >1.0 and ≤2.0, and antagonistic if FIC >2.0.