Table 1. . Light and dark MIC values for Escherichia coli, methicillin-resistant Staphylococcus aureus, two tetracycline resistant E. coli strains using four tetracyclines.
| Microorganism | Tetracycline | Dark MIC (μg/ml)† | Light MIC (μg/ml) | p-value |
|---|---|---|---|---|
| Escherichia coli UTI | DMCT | 0.16–0.32 | 0.16–032 | n.s. |
| DOTC | 0.625 | 0.625 | n.s. | |
| TC | 1.25 | 1.25 | n.s. | |
| MC | 0.32–0.625 | >5 | <0.0001 | |
| MRSA | DMCT | 0.08 | 0.02–0.04 | 0.0001 |
| DOTC | 0.08–0.16 | 0.01–0.02 | 0.0003 | |
| TC | 0.16–0.32 | 0.08–0.16 | 0.018 | |
| MC | 0.04 | 0.04 | n.s. | |
| E. coli 5-66 | DMCT | 64 | 16–32 | 0.0002 |
| DOTC | 16 | 4–8 | 0.0134 | |
| E. coli 3-62 | DMCT | 64 | 16–32 | 0.0004 |
| DOTC | 16–32 | 8 | 0.0134 |
p-values determined by two-tailed unpaired t-test.
†
As is customary values are given in microgram per milliliter. In order to compare with concentrations given in micrometer in Figure 3, it should be noted that 1 μg/ml is equivalent to 2.25 μM for DOTC and 2 μM for DMCT.
DMCT: Demeclocycline; DOTC: Doxycycline; MC: minocycline; MIC: Minimum inhibitory concentration; MRSA: Methicillin-resistant Staphylococcus aureus; n.s: Not significant; TC: Tetracycline; UTI: Urinary tract infection.