Research Article

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

Table 2

Mean of the minimum inhibitory concentration (MIC), 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 combinationMIC (μg/mL)FICMIC reduction fold of ATBFICI/interpretation
AloneCombined
ATBNPsATBNPsATBNPs

Cef+Cur54.1264011.20280.420.210.444.830.65/A
Cef+Pip61.89>102421.68485.050.350.472.850.82/A
Cef+Plu61.89>102429.685000.480.492.090.97/A
Cef+Thy61.89>10241.95165.050.030.1631.740.19/S
Cef+Quer61.8997.6812.9523.580.210.244.780.45/S
Cef+Sin A61.8935.379.375.420.150.156.610.30/S
Ami+Cur11.266402.20176.840.200.285.120.47/S
Ami+Pip11.26>10245.68498.530.500.491.980.99/A
Ami+Plu11.26>10246.50471.580.580.461.731.04/I
Ami+Thy11.26>10242.90217.260.260.213.880.47/S
Ami+Que11.2697.682.0317.890.180.185.550.36/S
Ami+Sin A11.2635.370.162.200.010.0670.380.08/S
Nor+Cur11.68660.210.3888.420.030.1330.740.17/S
Nor+Pip11.68>10246.37519.580.550.511.831.05/I
Nor+Plu11.68>10247.68326.740.660.321.520.98/A
Nor+Thy11.68>10243.25377.260.280.373.590.65/A
Nor+Que11.6897.681.5526.950.130.287.540.41/S
Nor+Sin A11.6835.370.586.050.050.1720.140.22/S

Geometric mean value of 19 isolates. 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.