Antibacterial activity of mometasone furoate.

OBJECTIVE To test the antibacterial properties of the topical corticoid mometasone furoate, which is used as a nasal spray. DESIGN The activity of mometasone (0.01%, 0.1%, and 0.5%) in buffer solution against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pyogenes, and Streptococcus milleri was tested by quantitative killing assays. SETTING In vitro study. MAIN OUTCOME MEASURE Reduction of viable bacteria and fungi in quantitative killing assays. RESULTS Mometasone (0.5%) reduced viable counts of S pyogenes and S milleri by 99.99% and 99.00%, respectively, after 24 hours of incubation, whereas colony-forming units (CFUs) of S aureus, P aeruginosa, and E coli were not affected by the corticoid. Mometasone (0.1%) caused a decrease in CFUs of S pyogenes of 99.90% to 99.99%, while it led to a 99.00% reduction in CFUs of S milleri, but only if low bacterial counts of 1 x 10(4) CFUs/mL were incubated. By contrast, the use of mometasone at a low concentration (0.01%) demonstrated an increase in CFUs of S milleri if the baseline bacterial count was low (1 x 10(4) CFUs/mL). CONCLUSION Mometasone demonstrates antimicrobial activity against streptococci.