Synergistic Antibiofilm Effect of Thymol and Piperine in Combination with Aminoglycosides Antibiotics against Four Salmonella enterica Serovars

Table 3

Minimum biofilm eradication concentration (MBEC) and effects of the combination of thymol/piperine with amikacin, kanamycin, and streptomycin against preformed biofilm of four Salmonella enterica serovars.

Isolates	Antibiotics	MBEC (µg/mL)							MBEC reduction fold (antibiotic)		FICI/INT
		Alone			Combined
		ATB	Thy	Pip	ATB/Thy	Thy	ATB/Pip	Pip	ATB/Thy	ATB/Pip	ATB/Thy	ATB/Pip
S. Typhi ATCC 6539	Amikacin	128	512	1024	8	256	4	1024	16	64	0.56/Ad	1.03/I
	Kanamycin	128	512	1024	4	128	16	256	32	8	0.28/S	0.38/S
	Streptomycin	128	512	1024	64	128	8	1024	2	16	0.75/Ad	1.06/I
S. Enteritidis	Amikacin	128	1024	1024	2	256	8	512	64	16	0.27/S	0.56/Ad
	Kanamycin	64	1024	1024	4	256	8	512	16	8	0.31/S	0.63/Ad
	Streptomycin	128	1024	1024	16	1024	8	1024	8	16	1.13/I	1.06/I
S. Typhi	Amikacin	128	512	1024	8	32	16	512	16	8	0.13/S	0.63/Ad
	Kanamycin	128	512	1024	8	256	8	1024	16	16	0.56/Ad	1.06/I
	Streptomycin	256	512	1024	16	512	16	256	16	16	1.06/I	0.31/S
S. Typhimurium	Amikacin	64	512	1024	4	128	8	512	16	8	0.31/S	0.63/Ad
	Kanamycin	128	512	1024	8	128	8	128	16	16	0.31/S	0.19/S
	Streptomycin	128	512	1024	16	256	16	256	8	8	0.63/Ad	0.38/S
S. Choleraesuis	Amikacin	64	512	1024	1	128	2	128	64	16	0.27/S	0.16/S
	Kanamycin	64	512	1024	4	512	4	512	16	16	1.06/I	0.56/Ad
	Streptomycin	256	512	1024	16	256	32	512	16	8	0.56/Ad	0.63/Ad

MBEC: minimum biofilm eradication concentration, Thy: thymol, Pip: piperine, ATB/Thy: combination of antibiotic with thymol, ATB/Pip: combination of antibiotic with piperine, FICI: fractional inhibitory concentration index, INT: interpretation, S: synergy, Ad: additivity, I: indifference.