Table 5.
Fractional Inhibitory Concentration
| P seudomonas | Disinfectants | MIC in the | Checkerboard | |
|---|---|---|---|---|
| aeruginosa strains | Combination | Combination (ppm) | FICI | Interpretation |
| P.aer 123 | Polyquad-1+Aldox | 5.64 + 90.9 | 1.5 | No interaction |
| Polyquad-1+PAPB | 45.45 + 90.9 | 6 | Antagonism | |
| Polyquad-1+Alexidine | 5.64 + 5.64 | 2.5 | No interaction | |
| Polyquad-1+PAPB+Alexidine | 0.78 + 2.84 + 0.78 | 0.36 | Synergy | |
| P.aer 127 | Polyquad-1+Aldox | 2.84 + 11.36 | 1.125 | No interaction |
| Polyquad-1+PAPB | 4.5 + 90.9 | 3.6 | No interaction | |
| Polyquad-1+Alexidine | 2.5 + 2 .84 | 1.2 | No interaction | |
| Polyquad-1+PAPB+Alexidine | 0.0097 + 5.64 + 0.39 | 0.25 | Synergy | |
| P.aer 155 | Polyquad-1+Aldox | 11.36 + 45.45 | 3 | No interaction |
| Polyquad-1+PAPB | 45.45 + 90.9 | 8 | Antagonism | |
| Polyquad-1+ALX | 45.45+ 5 | 16.4 | Antagonism | |
| Polyquad-1+PAPB+Alexidine | 0.39+ 2.84+ 0.78 | 0.4 | Synergy |
Combined MIC is the that of each disinfectant when tested in combination with other disinfectants.
Aldox, myristamidopropyl dimethylamine; ALX, alexidine; FICI, fractional inhibitory concentration index (synergy: FICI ≤0.5; no interaction: 0.5 < FICI ≤ 4; and antagonism: FICI > 4); MIC, minimum inhibitory concentration; PAPB, polyaminopropyl biguanide; Polyquad-1, polyquaternium-1.