Table 3.
Evaluation of antimicrobial activity of CasuL in combination with tetracycline against Staphylococcus isolates from bovine and caprine mastitis
| Isolate | MIC (µg/ml) | FICI | Effect | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Alone | In CasuL + tetracycline combination | ||||||||
| CasuL | Tetracycline | CasuLa | Tetracyclinea | ||||||
| Sa (Staphylococcus aureus) | 3.75 | 0.50 | 2.30 × 10−4 | 0.12 | 0.250 | Synergistic | |||
| Ssp6PD (Staphylococcus sp.) | 3.75 | 2.00 | 3.66 × 10−3 | 3.12 × 10−2 | 0.016 | Synergistic | |||
| Ssp01 (Staphylococcus sp.) | 15.00 | 1.00 | ND | ND | NC | Antagonistic | |||
| Ssp5D (Staphylococcus sp.) | 3.75 | 4.00 | 6.00 × 10−5 | 4.0 | 1.000 | Additive | |||
Classification: synergistic (FICI ≤ 0.5), additive (0.5 < FICI ≤ 1), indifferent (1 < FICI ≤ 2) or antagonistic (FICI > 2).
Abbreviations: FICI, fractional inhibitory concentration index; MIC, minimum inhibitory concentration; NC, not calculated; ND, not detected.
a
The values correspond to the concentration of CasuL or ampicillin in the microplate well containing both compounds.