In Vitro Antistaphylococcal Effects of Embelia schimperi Extracts and Their Component Embelin with Oxacillin and Tetracycline
Table 2
In vitro inhibitory activity of embelin in combination with oxacillin against S. aureus.
MICs (g/mL)
MICs of oxacillin in combination with listed embelin concentrations (μg/mL)
S. aureus strain
Emb
Ox
+Emb 4 μg/mL
+Emb 2 μg/mL
+Emb 1 μg/mL
+Emb 0.5 μg/mL
+Emb 0.25 μg/mL
MIC
ΣFIC
MIC
ΣFIC
MIC
ΣFIC
MIC
ΣFIC
MIC
ΣFIC
ATCC 29213
32
0.5
0.17
0.458
0.17
0.396
0.17
0.365
0.17
0.349
x
x
ATCC 43300
10.67
21.33
0.33
0.391
0.33
0.203
5.58
0.355
7.33
0.391
13.33
0.648
EMRSA15
10.67
85.33
24.67
0.477
53.33
0.719
74.67
0.922
74.67
0.898
74.67
0.899
MRSA1
8
128
2
0.516
64
0.750
64
0.625
64
0.563
64
0.531
MdRSA2
10.67
341.33
109.33
0.695
256
0.938
341.33
1.094
341.33
1.047
341.33
1.023
MdRSA3
8
341.33
10.67
0.531
266.67
1.031
341.33
1.125
341.33
1.063
341.33
1.031
MRSA4
8
64
64
1.500
64
1.250
64
1.125
64
1.063
64
1.030
TRSA1
8
0.42
0.05
0.631
0.25
0.850
0.33
0.925
0.33
0.863
0.33
0.831
TRSA2
10.67
0.33
0.01
0.398
0.33
1.188
0.33
1.094
0.33
1.047
0.33
1.023
MIC: minimum inhibitory concentration expressed as an average from three independent experiments, each performed in triplicate; Emb: embelin; Ox: oxacillin; ATCC: American type culture collection; MRSA: methicillin-resistant S. aureus; EMRSA: epidemic MRSA; TRSA: tetracycline-resistant S. aureus; MdRSA: multidrug-resistant S. aureus; x: not tested; ΣFIC: sum of fractional inhibitory concentrations: the combinatory effect is evaluated as follows: synergy if ΣFIC ≤0.5; additive if ΣFIC >0.5 and ≤1; indifferent if ΣFIC >1 and <2; and antagonistic if ΣFIC ≥2.
