. 2013 Jan 16;14(1):1802–1821. doi: 10.3390/ijms14011802

Table 3.

Effect of C and ECg on antibacterial effects of six β-lactam antibiotics against 45 clinical MRSA strains. Synergistic activities of C and ECg in combination with six β-lactams antibiotics (oxacillin, ampicillin, ampicillin/sulbactam, cefazolin, cefepime and imipenem/cilastatin) were tested by checkerboard method. FICI values were calculated as described in Experimental Section.

Antibiotics	MIC (mg/L) of β-lactam antibiotics
	Concentration of C ^a + ECg ^b (mg/L)

	0			16 + 2				32 + 4

	Range	MIC₅₀	MIC₉₀	Range	MIC₅₀	MIC₉₀	FICI ^c	Range	MIC₅₀	MIC₉₀	FICI ^c
oxacillin	128–512	256	512	4–512	128	256	0.56 ± 0.32 (13/45)	4–256	32	256	0.31 ± 0.22 (36/45)
ampicillin	32–512	64	128	2–256	16	64	0.37 ± 0.26 (30/45)	2–256	8	32	0.29 ± 0.24 (39/45)
ampicillin/sulbactam	8–32	32	32	2–32	16	32	0.58 ± 0.29 (14/45)	2–16	8	16	0.39 ± 0.23 (33/45)
cefazolin	4–512	256	512	4–512	128	256	0.47 ± 0.33 (20/45)	4–256	32	128	0.25 ± 0.18 (39/45)
cefepime	8–2048	1024	1024	8–1024	256	512	0.45 ± 0.23 (18/45)	8–1024	128	512	0.30 ± 0.20 (39/45)
imipenem/cilastatin	4–512	128	256	4–512	32	64	0.36 ± 0.25 (29/45)	4–512	4	32	0.23 ± 0.25 (41/45)

Antibiotics		MIC (mg/L) of β-lactam antibiotics
		Concentration of C^a+ ECg^b(mg/L)

		64 + 8						128 + 16

		Range		MIC₅₀	MIC₉₀	FICI^c		Range	MIC₅₀	MIC₉₀	FICI^c

oxacillin		4–256		4	128	0.28 ± 0.19 (42/45)		4–256	4	4	0.41 ± 0.22 (31/45)
ampicillin		2–256		2	16	0.27 ± 0.19 (42/45)		2–256	2	2	0.29 ± 0.22 (31/45)
ampicillin/sulbactam		2–16		2	4	0.30 ± 0.19 (42/45)		2–16	2	2	0.44 ± 0.12 (33/45)
cefazolin		4–64		4	32	0.23 ± 0.15 (44/45)		4–4	4	4	0.39 ± 0.21 (32/45)
cefepime		8–256		8	64	0.25 ± 0.17 (44/45)		8–16	8	8	0.39 ± 0.23 (32/45)
imipenem/cilastatin		4–512		4	4	0.28 ± 0.30 (42/45)		4–512	4	4	0.45 ± 0.26 (32/45)

For C, the MIC range, MIC₅₀, MIC₉₀ against 45 MRSA clinical strains were 512–4096 mg/L, 2048 mg/L and 4096 mg/L, respectively;

For ECg, the MIC range, MIC₅₀, MIC₉₀ against 45 MRSA clinical strains were 32–1024 mg/L, 64 mg/L and 1024 mg/L, respectively;

Data are expressed as means ± standard deviations. Values in parentheses represent the number of strains for which drug combinations resulted in synergism/number of strains tested.