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 combination
MIC† (μg/mL)
FIC
MIC reduction fold of ATB
FICI/interpretation
Alone
Combined
ATB
NPs
ATB
NPs
ATB
NPs
Cef+Cur
54.12
640
11.20
280.42
0.21
0.44
4.83
0.65/A
Cef+Pip
61.89
>1024
21.68
485.05
0.35
0.47
2.85
0.82/A
Cef+Plu
61.89
>1024
29.68
500
0.48
0.49
2.09
0.97/A
Cef+Thy
61.89
>1024
1.95
165.05
0.03
0.16
31.74
0.19/S
Cef+Quer
61.89
97.68
12.95
23.58
0.21
0.24
4.78
0.45/S
Cef+Sin A
61.89
35.37
9.37
5.42
0.15
0.15
6.61
0.30/S
Ami+Cur
11.26
640
2.20
176.84
0.20
0.28
5.12
0.47/S
Ami+Pip
11.26
>1024
5.68
498.53
0.50
0.49
1.98
0.99/A
Ami+Plu
11.26
>1024
6.50
471.58
0.58
0.46
1.73
1.04/I
Ami+Thy
11.26
>1024
2.90
217.26
0.26
0.21
3.88
0.47/S
Ami+Que
11.26
97.68
2.03
17.89
0.18
0.18
5.55
0.36/S
Ami+Sin A
11.26
35.37
0.16
2.20
0.01
0.06
70.38
0.08/S
Nor+Cur
11.68
660.21
0.38
88.42
0.03
0.13
30.74
0.17/S
Nor+Pip
11.68
>1024
6.37
519.58
0.55
0.51
1.83
1.05/I
Nor+Plu
11.68
>1024
7.68
326.74
0.66
0.32
1.52
0.98/A
Nor+Thy
11.68
>1024
3.25
377.26
0.28
0.37
3.59
0.65/A
Nor+Que
11.68
97.68
1.55
26.95
0.13
0.28
7.54
0.41/S
Nor+Sin A
11.68
35.37
0.58
6.05
0.05
0.17
20.14
0.22/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.