Canadian Journal of Infectious Diseases and Medical Microbiology

Research Article

Synergistic Antibiofilm Efficacy of Thymol and Piperine in Combination with Three Aminoglycoside Antibiotics against Klebsiella pneumoniae Biofilms

Table 3

Minimum biofilm eradication concentration (MBEC) of thymol, piperine, aminoglycoside, and fractional inhibitory concentration index (FICI) of combination against K. pneumoniae.


	MBEC (μg/mL)							MBIC reduction fold of antibiotics		FICI/interpretation
	Alone			Combined^∗				(ATB/Thy)^α	(ATB/Pip)^α	(ATB/Thy)^ο	(ATB/Pip)^ο
	ATB	Thy	Pip	(ATB/Thy)	(Thy)	(ATB/Pip)	Pip	(ATB/Thy)^α	(ATB/Pip)^α	(ATB/Thy)^ο	(ATB/Pip)^ο

Streptomycin
Kp55	32	1024	1024	0.5	64	32	256	64	1	0.08/S	1.25/I
Kp02	32	1024	1024	0.5	64	16	128	64	2	0.08/S	0.63/Ad
Kp03	64	512	1024	4	64	32	512	16	2	0.19/S	1/Ad
Kp04	64	512	1024	2	128	8	256	32	8	0.28/S	0.38/S
Kp05	128	512	1024	4	128	64	512	32	2	0.28/S	1/Ad
Amikacin
Kp55	32	1024	1024	32	256	16	1024	1	2	1.25/I	1.50/I
Kp02	64	1024	1024	16	1024	64	512	4	1	1.25/I	1.5/I
Kp03	128	512	1024	32	128	32	512	4	4	0.50/S	0.75/Ad
Kp04	64	512	1024	32	256	64	1024	2	1	1/Ad	2/I
Kp05	64	512	1024	8	64	32	1024	8	2	0.25/S	1.5/I
Kanamycin
Kp55	64	1024	1024	64	16	8	128	1	8	1.02/I	0.25/S
Kp02	32	1024	1024	16	512	16	256	2	2	1/Ad	0.75/Ad
Kp03	64	512	1024	32	128	32	512	2	2	0.75/Ad	1/Ad
Kp04	64	512	1024	1	128	4	32	64	16	0.27/S	0.09/S
Kp05	64	512	1024	8	64	16	128	16	8	0.25/S	0.38/S

MBEC: minimal biofilm eradication concentration, ATB: antibiotic, Thy: thymol, Pip: piperine, (ATB/Thy): concentration of antibiotic in combination with thymol, (Thy): concentration of thymol in combination with antibiotic, (ATB/Pip): concentration of antibiotic in combination with piperine, (Pip): concentration of piperine in combination with antibiotic, (ATB/Thy)^α = concentration of antibiotic alone/(ATB/Thy), (ATB/Pip)^α = concentration of antibiotic alone/(ATB/Pip), (ATB/Thy)^ο = (ATB/Thy)/concentration of antibiotic alone + (Thy)/concentration of thymol alone, (ATB/Pip)^ο = (ATB/Pip)/concentration of antibiotic alone + (Pip)/concentration of piperine alone, FICI: fractional inhibitory concentration index, S: synergy, Ad: additivity, I: indifference.