Table 7.

LEOs (L.A.V., L.A.S., and L.H.G.) in combination with ampicillin—fractional inhibitory concentration (FIC) and FIC indices (FICI).

	MIC				MIC MIX			FIC EO			FIC Ampicillin			FICI
ATCC strain	L.A.V	L.A.S	L.H.G	Amp	L.A.V	L.A.S	L.H.G	L.A.V	L.A.S	L.H.G	L.A.V	L.A.S	L.H.G	L.A.V	L.A.S	L.H.G
S. pyogenes	0.5	1	4	0.25	0.06	0.25	0.5	0.360	1.25	2.12	0.24	1.000	2	0.36	1.25	2.125
S. aureus	1	2	2	1.5	0.015	0.03	0.03	0.015	0.015	0.015	0.02	0.040	0.04	0.035	0.055	0.055
L. monocytogenes	4	1	1	1.5	0.06	0.125	0.125	0.015	0.125	0.125	0.04	0.083	0.083	0.06	0.21	0.21
B. cereus	0.5	1	4	1.75	0.03	0.125	0.015	0.060	0.125	0.004	0.017	0.071	0.009	0.08	0.2	0.01
C. perfringens	4	4	2	2.25	0.25	0.5	0.007	0.063	0.125	0.004	0.111	0.222	0.003	0.17	0.35	0.01
P. aeruginosa	2	nd *	4		0.125	0.007	0.125	0.063	0.03	0.5	nu *	nu	nu	nd	nd	nd
S. flexneri	nd	nd	0.125	8.25	0.007	0.015	0.125	nd	nd	1	0.01	0.020	0.01	nd	nd	1.01
E. coli	4	4	2	4.8	4	1	0.125	1.000	0.25	0.063	0.833	0.208	0.026	1.83	0.46	0.09
S. typhimurium	1	1	2	8	0.125	0.125	0.25	0.125	0.125	0.125	0.016	0.016	0.031	0.14	0.14	0.16
H. influenzae	4	4	1	6.5	4	0.5	0.125	1.000	0.125	0.125	0.615	0.077	0.019	1.62	0.2	0.14

* nd—not detected, i.e., the values tested had no efficacy; * nu—not usable (resistant); MIC—minimum inhibitory concentration; FIC—fractional inhibitory concentration; FICI—fractional inhibitory concentration index; FIC EO—FIC of EO = MIC of EO in combination with ampicillin/MIC of EO alone; FIC of ampicillin = MIC of ampicillin in combination with EO/MIC of ampicillin alone; FIC index = FIC of EO + FIC of ampicillin; FICI ≤ 0.5—synergistic; FICI > 0.5–1.0—additive; FICI > 1.0–4.0—no interaction; FICI > 4.0—antagonistic.