Table 4.
Minimum inhibitory concentration (MIC) of anthocyanin-rich extracts from the four varieties of blueberries, expressed in mg/mL.
| Type of Strain | UTI Strains | ATCC Standard Strains | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Gram staining of the strains | Gram-negative | Gram-positive | Gram-negative | Gram-positive | |||||
| Strains | Klebsiella pneumoniae ssp. pneumoniae | Providencia stuartii | Escherichia coli β-Haemolytic | Pseudomonas aeruginosa | Micrococcus spp. | Escherichia coli ATCC 25922 | Salmonella Enteritidis ATCC 13076 | Listeria monocytogenes ATCC 19114 | |
| Sample | |||||||||
| Cristina Blue | 9.52 ± 0 Ac | 1.78 ± 0.65 A,a | 3.74 ± 1.372 A,b | 0.85 ± 0.31 A,a | 1.41 ± 0.65 A,a | 3.74 ± 1.37 A,b | 2.16 ± 0 C,a | 4.54 ± 0 D,b | |
| Star | 9.52 ± 0 Ad | 1.78 ± 0.65 A,a,b | 3.74 ± 1.372 A,c | 0.49 ± 0 A,a | 2.57 ± 1.79 A,b,c | 3.74 ± 1.37 A,c | 1.03 ± 0 B,a,b | 2.16 ± 0 C,a,b,c | |
| Snowchaser | 9.52 ± 0 Ad | 1.78 ± 0.65 A,a,b | 3.74 ± 1.372 A,c | 0.58 ± 0.41 A,a | 1.78 ± 0.65 A,a,b | 3.74 ± 1.37 A,c | 1.78 ± 0.65 C,a,b | 2.16 ± 0 C,b | |
| Stella Blue | 9.52 ± 0 Ad | 1.78 ± 0.65 A,a,b | 3.74 ± 1.372 A,c | 0.40 ± 0.15 A,a | 0.76 ± 0.46 A,a,b | 3.74 ± 1.37 A,c | 2.16 ± 0 C,b | 1.41 ± 0.653 B,a,b | |
| Positive control (µg/mL) | 0.28 ± 0.20Aa | 1.45 ± 0.67 A,b | 0.12 ± 0.11 A,a | 3.85 ± 1.41 A,c | 0.02 ± 0 A,a | 0.05 ± 0.05 A,a | 0.69 ± 0.32 A,a,b | 0.02±0 A,b | |
Note: The data are presented as mean ± SD, n = 3. Different uppercase letters indicate statistically significant differences on the columns, and therefore differences among the samples, while the different lowercase indicate statistically significant differences on the rows, therefore differences among the different strains (Fisher LSD, p < 0.05). The negative control was 70% methanol, the solvent used for the dilution of the lyophilised anthocyanins, while the positive control was Gentamicin (with the initial concentration of stock solution of 0.4 mg/mL).