Antibiotic-Potentiating Effect of Some Bioactive Natural Products against Planktonic Cells, Biofilms, and Virulence Factors of Pseudomonas aeruginosa

Table 4

Mean of the minimum biofilm eradication concentration (MBEC), fractional inhibitory concentration (FIC), and fractional inhibitory concentration index (FICI) of antibiotics (ATB) and natural products (NPs) in combination against nineteen P. aeruginosa isolates.

Antimicrobial agent combination	MBEC (μg/mL)				FIC		MBEC reduction fold of ATB	FICI/interpretation
	Alone		Combined
	ATB	NPs	ATB	NPs	ATB	NPs
Cef+Cur	815.16	>2048	390.74	687.16	0.48	0.34	2.09	0.81/A
Cef+Pip	815.16	>2048	481.68	917.68	0.59	0.45	1.69	1.04/I
Cef+Plu	815.16	>2048	323.37	1671.16	0.40	0.82	2.52	1.21/I
Cef+Thy	815.16	>2048	279.58	970.11	0.34	0.47	2.92	0.82/A
Cef+Que	815.16	195.37	245.89	97.68	0.30	0.50	3.32	0.80/A
Cef+Sin A	815.16	303.16	129.68	80.84	0.16	0.27	6.29	0.43/S
Ami+Cur	330.11	>2048	89.26	410.95	0.27	0.20	3.70	0.47/S
Ami+Pip	330.11	>2048	80.84	1293.47	0.24	0.63	4.08	0.88/A
Ami+Plu	330.11	>2048	119.58	1455.16	0.36	0.71	2.76	1.07/I
Ami+Thy	330.11	>2048	85.89	1212.63	0.26	0.59	3.84	0.85/A
Ami+Que	330.11	195.37	82.53	79.16	0.25	0.41	4.00	0.66/A
Ami+Sin A	330.11	303.16	10.39	35.95	0.03	0.12	31.77	0.15/S
Nor+Cur	619.79	>2048	35.16	250.05	0.06	0.12	17.63	0.18/S
Nor+Pip	619.79	>2048	195.37	1455.16	0.32	0.71	3.17	1.03/I
Nor+Plu	619.79	>2048	353.68	1455.16	0.57	0.71	1.75	1.28/I
Nor+Thy	619.79	>2048	202.11	632.32	0.33	0.31	3.07	0.63/A
Nor+Que	619.79	195.37	118.74	72.42	0.19	0.37	5.22	0.56/A
Nor+Sin A	619.79	303.16	60.63	70.74	0.10	0.23	10.22	0.33/S

ATB: antibiotics; NPs: natural products; MBEC: minimum biofilm eradication concentration; Cef: ceftazidime; Ami: amikacin; Nor: norfloxacin; Cur: curcumin; Pip: piperine; Plu: plumbagin; Thy: thymol; Que: quercetin; Sin A: sinapic acid; S: synergy; A: additivity; I: indifference.