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Table 3 In vitro antibacterial activities of cinnamon oil, silver nanoparticles and their combination against S. agalactiae isolated from clinical bovine mastitis

From: Antimicrobial and antibiofilm potentials of cinnamon oil and silver nanoparticles against Streptococcus agalactiae isolated from bovine mastitis: new avenues for countering resistance

Isolate No. Zone diameters for the agar well diffusion method (mm)* MIC (μg/mL)** ΣFIC Interactive category
Cinnamon oil (%) Silver nanoparticles (%) Cinnamon oil Silver nanoparticles Cinnamon oil/ Silver nanoparticles
100 50 25 100 50 25
1 38 29 20 31 24 18 0.063 8 0.00012/0.125 0.02 Synergistic
2 40 31 23 29 22 17 0.004 8 0.0005/0.250 0.16 Synergistic
3 40 30 22 30 23 16 0.016 8 0.0005/0.250 0.06 Synergistic
4 39 28 19 28 25 19 0.016 16 0.002/0.125 0.13 Synergistic
5 36 27 18 30 21 17 0.008 16 0.002/0.125 0.26 Synergistic
6 36 26 18 28 21 15 0.031 16 0.0005/0.250 0.03 Synergistic
7 40 33 21 29 23 18 0.063 8 0.0005/0.250 0.04 Synergistic
8 36 28 21 30 21 17 0.016 8 0.002/0.125 0.14 Synergistic
9 40 32 23 30 22 16 0.004 8 0.0005/0.250 0.16 Synergistic
10 40 30 22 28 22 16 0.063 16 0.00012/0.125 0.01 Synergistic
11 39 30 21 31 23 18 0.016 8 0.002/0.125 0.02 Synergistic
12 36 28 19 28 25 19 0.016 16 0.0005/0.250 0.05 Synergistic
13 36 26 18 29 22 17 0.031 8 0.0005/0.250 0.05 Synergistic
14 40 34 23 27 20 15 0.008 16 0.002/0.125 0.3 Synergistic
Mean ± SE 38.29 ± 0.50a 29.43 ± 0.66b 20.57 ± 0.51c 29.14 ± 0.33a 22.43 ± 0.40b 17.00 ± 0.35c 0.01±
0.01a
11.43±
1.10a
0.0010 ± 0.0002b/0.19 ± 0.02b
  1. MIC minimum inhibitory concentration, ΣFIC fractional inhibitory concentration index; SE, standard error
  2. * Means ± standard errors of the inhibition zones` diameters for different concentrations (25, 50 and 100%) of cinnamon oil or silver nanoparticles carrying different superscripts are highly significant (P < 0.0001)
  3. ** Means ± standard errors of the MIC values of cinnamon oil or silver nanoparticles (serial dilutions were done for each antibacterial agent starting from 1024 μg/mL and downwards) and their combination carrying different superscripts are highly significant (P < 0.0001)