Antimicrobial Activity of Coronarin D and Its Synergistic Potential with Antibiotics
Table 3
Fractional inhibitory concentration index () and minimal inhibitory concentration (MIC) of antibiotics in combination with coronarin D.
MIC in g/mL
S. aureus
S. epidermidis
E. faecalis
B. cereus
Coronarin D (CD)
12.5
12.5
50
6.25
Penicillin G
0.048
0.048
0.78
100
Lowest antibiotic in combination with CD (concentration of CD, gaina)
0.006 (0.5MIC, 8)
0.006 (0.5MIC, 8)
1.56 (0.5MIC, 0.5)
1.56 (0.5MIC, 64)
Penicillin G + CD at 0.25MIC (gain)
0.024 (2)
0.024 (2)
1.56 (0.5)
6.25 (16)
(concentration of CD/concentration of antibiotic)
0.625 (6.25/0.006)
0.5625 (1.56/0.024)
2.0625 (3.12/1.56)
0.25 (0.78/12.5)
Oxacillin
1.56
0.78
12.5
25
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.024 (0.5MIC, 64)
0.006 (0.5MIC, 130)
0.097 (0.5MIC, 128)
0.097 (0.5MIC, 258)
Oxacillin + CD at 0.25MIC (gain)
0.048 (32)
0.024 (32)
0.78 (16)
0.195 (128)
(concentration of CD/concentration of antibiotic)
0.25 (1.56/0.097)
0.1875 (1.56/0.048)
0.25 (6.25/1.56)
0.25 (0.78/3.12)
Polymyxin B
25
50
200
50
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.78 (0.5MIC, 32)
3.12 (0.5MIC, 16)
50 (0.5MIC, 4)
0.78 (0.5MIC, 64)
Polymyxin B + CD at 0.25MIC (gain)
3.12 (8)
12.5 (4)
200 (1)
1.56 (32)
(concentration of CD/concentration of antibiotic)
0.375 (3.12/3.12)
0.375 (1.56/12.5)
0.75 (25/50)
0.28 (1.56/1.56)
Ciprofloxacin
0.195
0.39
1.56
0.39
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.012 (0.5MIC, 16)
0.0015 (0.5MIC, 260)
0.012 (0.5MIC, 130)
0.006 (0.5MIC, 64)
Ciprofloxacin + CD at 0.25MIC (gain)
0.048 (4)
0.048 (8)
0.097 (16)
0.048 (8)
(concentration of CD/concentration of antibiotic)
0.5 (3.12/0.048)
0.375 (1.56/0.097)
0.3125 (12.5/0.097)
0.3125 (0.39/0.097)
Rifampicin
0.003
0.0003
0.78
0.024
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.0007 (0.5MIC, 4)
0.00015 (0.25MIC, 2)
0.024 (0.5MIC, 32)
0.024 (0.5MIC, 1)
Rifampicin + CD at 0.25MIC (gain)
0.003 (1)
0.00015 (2)
0.195 (4)
0.024 (1)
(concentration of CD/concentration of antibiotic)
0.75 (6.25/0.0007)
0.75 (3.12/0.00015)
0.5 (12.5/0.195)
1.5 (3.12/0.024)
Chloramphenicol
12.5
12.5
12.5
6.25
Lowest antibiotic in combination with CD (concentration of CD, gaina)
12.5 (0.5MIC, 1)
3.12 (0.5MIC, 4)
6.25 (0.25MIC, 2)
0.048 (0.5MIC, 130)
Chloramphenicol + CD at 0.25MIC (gaina)
12.5 (1)
12.5 (1)
6.25 (2)
3.12 (2)
(concentration of CD/concentration of antibiotic)
1.5 (6.25/12.5)
0.75 (6.25/3.12)
0.75 (12.5/6.25)
0.5078 (3.12/0.048)
Tetracycline
0.195
0.195
0.195
0.39
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.195 (0.5MIC, 1)
0.048 (0.5MIC, 4)
0.097 (0.5MIC, 2)
0.39 (0.5MIC,1)
Tetracycline + CD at 0.25MIC (gain)
0.195 (1)
0.097 (2)
0.195 (1)
0.39 (1)
(concentration of CD/concentration of antibiotic)
1.5 (6.25/0.195)
0.75 (3.12/0.097)
1 (25/0.097)
1.5 (3.12/0.39)
Gentamicin
3.12
0.39
12.5
0.78
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.024 (0.5MIC, 130)
0.006 (0.5MIC, 65)
0.048 (0.5MIC, 260)
0.024 (0.5MIC, 32)
Gentamicin + CD at 0.25MIC (gain)
0.195 (16)
0.012 (32)
0.097 (128)
0.195 (4)
(concentration of CD/concentration of antibiotic)
0.25 (1.56/0.39)
0.1875 (1.56/0.024)
0.15625 (6.25/0.39)
0.375 (0.78/0.195)
Erythromycin
0.39
0.78
0.39
3.12
Lowest antibiotic in combination with CD (concentration of CD, gain)
0.195 (0.25MIC, 2)
0.195 (0.5MIC, 4)
0.195 (0.5MIC, 2)
0.78 (0.5MIC, 4)
Erythromycin + CD at 0.25MIC (gain)
0.195 (2)
0.78 (1)
0.39 (1)
1.56 (2)
(concentration of CD/concentration of antibiotic)
0.75 (3.12/0.195)
0.75 (6.25/0.195)
1 (25/0.195)
0.75 (3.12/0.78)
gain >1: decrease concentration of antibiotic, <1: increase concentration of antibiotic, and 1: no effect.
bThe best fractional inhibitory concentration index; ≤ 0.5 means total synergism, 0.5 < ≤ 0.75 means partial synergism, 0.75 < ≤ 2 means no effect, and > 2 means antagonism.
