Table 1.

Synergetic activity of rifampicin and vancomycin with tridecaptin M against Gram-negative bacteria.

Strain	Tri-M MIC (µg/mL)	Antibiotic	Tri-M Concentration (µg/mL)	MIC (µg/mL)	Potentiation Factor	FICI
A. baumannii ATCC 19606	32	Vancomycin	0	128
			2	128	1	-
			4	32	4	0.375
			8	8	16	0.312
		Rifampicin	0	4
			2	2	2	0.562
			4	1	4	0.375
			8	0.25	16	0.312
K. pneumoniae ATCC 700603	4	Vancomycin	0	128
			0.25	128	1	-
			0.5	128	1	-
			1.0	128	1	-
		Rifampicin	0	32
			0.25	32	1	-
			0.5	32	1	-
			1.0	32	1	-
P. aeruginosa ATCC 27853	256	Vancomycin	0	256
			4	256	1	-
			8	256	1	-
			16	256	1	-
		Rifampicin	0	64
			4	32	2	0.515
			8	32	2	0.531
			16	32	2	0.562

Tri-M—tridecaptin M; FICI—fractional inhibitory concentration index. FICI of ≤0.5 was considered as synergy. (-) represents no change in MIC, and hence, FICI was not calculated for these.