TABLE 1.
Overview of the disinfectants used and their antimicrobial properties
| Disinfectant [units] | Minimum inhibitory concentration (MIC)a | Minimum bactericidal concentration (MBC)a | Concentration in time–kill and evolution assay | Predicted persister fraction gb |
|---|---|---|---|---|
| Hydrogen peroxide (H2O2) [mM] | 12.5–25 | 12.5–25 | 75 | 0 |
| Glutaraldehyde (GTA) [%] | 0.08–0.16 | 0.08–0.16 | 0.015c | 0 |
| Chlorhexidine (CHX) [µg/mL] | 6.25–9.375 | 18.75–25 | 100 | 0 |
| Benzalkonium chloride (BAC) [µg/mL] | 31.8–35.4 | 35.4–53.1 | 42.5 | 3 × 10−3 [2 × 10−3 – 6 × 10−3] |
| Didecyldimethyl-ammonium chloride (DDAC) [µg/mL] | 16–24 | 16–24 | 28 | 1.4 × 10−4 [3.6 × 10−5 – 5 × 10−4] |
| Isopropanol (ISO) [%] | 2.2–4.4 | 4.4–8.75 | 12 | 7.6 × 10−4 [2.5 × 10−4 – 2.3 × 10−3] |
Concentrations tested in the MIC and MBC assays: H2O2 [mM]: 0.39, 0.78, 1.56, 3.125, 6.25, 12.5, 25, 50, 100, 200; glutaraldehyde [%]: 0.02, 0.04, 0.08, 0.16, 0.23, 0.31, 0.47, 0.63, 0.94, 1.25; chlorhexidine [µg/mL]: 2, 3, 4, 5, 6.25, 9.375, 12.5, 18.75, 25, 35; benzalkonium chloride [µg/mL]: 5.3, 7.1, 14.2, 17.7, 21.2, 24.8, 28.3, 31.8, 35.4, 53.1; DDAC [µg/mL]: 14, 16, 24, 32, 40, 48, 56, 64, 72, 80; isopropanol [%]: 0.07, 0.14, 0.275, 0.55, 1.1, 2.2, 4.4, 8.75, 17.5, 35.
Parameter values for best model fits are given in Table S1 . The range indicates the upper and lower limit of the calculated persister fraction.
The lower concentration in the time–kill assay compared to the MBC for GTA is explained by the strong effect of organic matter in LB used for MBC determination compared to phosphate-buffered saline used for the time–kill assay.