Table II.
Comparison between the MICs (µg/mL) of ciprofloxacin alone and ciprofloxacin in the presence of sildenafil, tadalafil, or vardenafil against standard bacterial strains
| Standard bacterial strains | MIC (µg/mL)* |
|||
|---|---|---|---|---|
| Ciprofloxacin | Ciprofloxacin + sildenafil | Ciprofloxacin + tadalafil | Ciprofloxacin + vardenafil | |
| Escherichia coli | 0.02 (0.01) | 1300 (100) | 1700 (100) | 1800 (100) |
| Staphylococcus aureus | 0.07 (0.05) | 1167 (58) | 1600 (100) | 1833 (58) |
| Pseudomonas aeruginosa | 0.07 (0.05) | 1267 (58) | 1700 (100) | 1867 (58) |
| Staphylococcus epidermidis | 0.14 (0.09) | 1100 (100) | 1500 (100) | 1700 (100) |
| Acinetobacter baumannii | 0.21 (0.07) | 1400 (100) | 1700 (100) | 1767 (58) |
| Proteus mirabilis | 0.17 (0.07) | 1600 (100) | 1900 (100) | 1933 (58) |
| Klebsiella pneumoniae | 0.14 (0.09) | 933 (57) | 1600 (100) | 1733 (58) |
We investigated whether PDEi could interfere with the antibacterial activity of ciprofloxacin.
Ciprofloxacin antibacterial action is inhibited when combined with PDEi
This observation is of significance, as ciprofloxacin is a commonly used antibiotic
⁎
The MIC values for ciprofloxacin alone were significantly (P < 0.05) lower than those of combination of ciprofloxacin with sildenafil, tadalafil, or vardenafil for all tested bacterial strains. Results are presented as mean (SD) of 3 independent experiments.