Table 1.
Optimal upper and lower bounds of zone diameter for predicting antibiotic resistance genotype from disk diffusion phenotype in our dataset.
| Antibiotic | Lower Bound (mm) | Upper Bound (mm) | Positive Predictive Value for genotype* | Resistance genotype |
|---|---|---|---|---|
| Oxacillin | 16.5 | 22.5 | 0.98 | mecA+ |
| Ampicillin | 17.5 | 17.5 | 0.9 | mecA+ |
| Amoxycillin | 20.5 | 20.5 | 0.97 | mecA+ |
| Amoxycillin + clavulanate | 28.5 | 28.5 | 0.82 | mecA+ |
| Cephalexin | 22.5 | 26.5 | 0.97 | mecA+ |
| Cefpodoxime | 20.5 | 25.5 | 0.98 | mecA+ |
| Cefovecin | 25.5 | 29.5 | 0.97 | mecA+ |
| Oxytetracycline | 11.5 | 27 | 1 (S = 1, n = 12) | tetM+ |
| Doxycycline | 17.5 | 28 | 1 (S = 1, n = 12) | tetM+ |
| Ciprofloxacin | 11.5 | 28.5 | 1 (S = 1, n = 16) | GyrA 84 L and Glr 80I |
| Enrofloxacin | 12.5 | 25 | 1 (S = 1, n = 16) | GyrA 84 L and Glr 80I |
| Trimethoprim | 5.5 | 19.5 | 1 (S = 1, n = 19) | dfrG+ |
| Clindamycin | 19 | 25 | 1 (S = 0.94, n = 18) | ermB+ |
| Chloramphenicol | 10.5 | 23.5 | 1 (S = 1, n = 15) | cat(pC221)+ |
| Gentamicin | 18.5 | 23 | 1 (S = 1, n = 18) | aac(6)/aph(2) + ** |
*For non-beta-lactam class antibiotics, positive predictive values are calculated for the 29 isolates which had genomes sequenced as part of this study. The sensitivity (S) of the test and the number (n) of resistance gene-containing genomes is shown in parentheses.
**Gentamicin resistance is also associated with genes aphIII and antIV in the sequenced NZ isolates.