Table 2.
Mean diameter of inhibition zones (mm) obtained by the agar diffusion method and the interpretation according to the European Committee on Antimicrobial Susceptibility Testing Breakpoint tables for interpretation of MICs and zone diameters Version 9.0, valid from 2019-01-01.
| A. a. strains | Inhibition Zone Diameter (mm) 1* | p-value | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| EO | Antimicrobials | |||||||||
|
O. vulgare 27.6 µg |
AMC 2 | AML 3 | DO 4 | SP 5 | CIP 6 | MH 7 | VA 8 | MTZ 9 | ||
| 25 µg | 25 µg | 30 µg | 100 µg | 5 µg | 30 µg | 30 µg | 5 µg | |||
| Breakpoints | ||||||||||
| S ≥ 15 R < 15 |
note10 | note11 | no info | S ≥ 30 R < 30 |
S ≥ 24 R < 21 |
no info | no info | |||
| clinical strain 1 | 37.33 ± 2.08 | 31.66 ± 1.15 | 30.33 ± 0.57 | 25.00 ± 0.00 ** | 29.66 ± 0.57 | 28.33 ± 0.57 | 36.00 ± 1.73 | 0.00 | 0.00 | <0.001 |
| S | S | S | S | -- | R | S | -- | R | ||
| clinical strain 2 | 51.33 ± 0.57 ** | 32.66 ± 0.57 ** | 29.33 ± 1.15 ** | 23.33 ± 0.57 | 22.66 ± 0.57 | 26.66 ± 0.57 ** | 36.33 ± 0.57 ** | 14.33 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | R | S | -- | R | ||
| clinical strain 3 | 65.66 ± 0.57 ** | 30.66 ± 0.57 | 30.66 ± 1.15 | 25.66 ± 0.57 | 28.66 ± 1.15 | 29.33 ± 1.15 | 38.33 ± 2.08 ** | 15.66 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | R | S | -- | R | ||
| clinical strain 4 | 63.66 ± 0.57 ** | 32.00 ± 1.00 | 28.66 ± 1.15 | 27.66 ± 0.57 | 27.66 ± 1.15 | 33.00 ± 1.00 | 39.33 ± 0.57 ** | 15.00 ± 0.00 ** | 0.00 | <0,001 |
| S | S | S | S | -- | S | S | -- | R | ||
| clinical strain 5 | 65.33 ± 0.57 ** | 31.00 ± 1.73 | 27.33 ± 0.57 ** | 23.33 ± 0.57 ** | 28.33 ± 0.57 | 31.66 ± 0.57 | 38.00 ± 1.73 ** | 14.66 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| clinical strain 6 | 56.33 ± 1.52 ** | 31.00 ± 0.00 | 27.66 ± 0.57 | 22.66 ± 0.57 ** | 27.00 ± 1.00 | 31.66 ± 0.57 | 34.66 ± 0.57 ** | 15.33 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| ATCC 43717 (Suny aB75) | 69.66 ± 0.57 ** | 40.33 ± 0.57 ** | 25.66 ± 0.57 | 28.33 ± 0.57 | 29.33 ± 0.57 | 30.66 ± 0.57 | 33.66 ± 0.57 ** | 24.66 ± 0.57 | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| ATTC 43718 Y4 | 65.33 ± 0.57 ** | 25.33 ± 0.57 | 34.33 ± 0.57 | 28.66 ± 0.57 | 28.66 ± 1.15 ** | 31.00 ± 1.00 ** | 33.33 ± 0.57 | 24.33 ± 0.57 | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| HK1651 (JP2) | 67.66 ± 1.52 ** | 28.33 ± 0.57 | 27.66 ± 0.57 | 28.33 ± 0.57 | 27.33 ± 0.57 | 34.33 ± 0.57 | 32.00 ± 1.73 | 23.66 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| HK 921 (JP2) | 37.00 ± 1.73 | 29.66 ± 0.57 | 27.66 ± 0.57 | 29.00 ± 0.00 | 25.66 ± 0.57 | 34.66 ± 0.57 | 29.33 ± 1.15 | 20.33 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | S | S | -- | R | ||
| HK1605 (non JP2) | 46.00 ± 1.00 ** | 29.33 ± 0.57 | 22.66 ± 0.57 ** | 26.66 ± 1.15 ** | 29.33 ± 1.15 | 29.33 ± 1.15 ** | 32.00 ± 1.00 ** | 19.66 ± 0.57 ** | 0.00 | <0.001 |
| S | S | S | S | -- | R | S | -- | R | ||
Calculation of Inhibition Zone Diameter includes the diameter of the well (6mm). * Mean ± Standard deviation; R: resistant;S: susceptible; EO: essential oil. ** p < 0.01: the inhibition zone diameter of a group (EO or antimicrobials) vs. the inhibition diameters of all other groups for each strain. 1 Diameter of inhibition zones, including diameter of well 6 mm, 2 Amoxicillin + Clavulanic Ac, 3 Amoxicillin, 4 Doxycycline; 5 Spiramycine; 6 Ciprofloxacine; 7 Minocycline; 8 Vancomycin; 9 Metronidazol. 10 Breakpoint is missing for Amoxicillin; however, susceptibility can be interred from ampicillin, for which the breakpoint is: S ≥ 16 and R< 16 mm. 11 breakpoint is missing for Doxycycline; however, isolates susceptible to tetracycline are also susceptible to Doxycycline. Breakpoint for tetracycline is: S ≥ 25 and R< 22.