Mediterr J Otol 2005:1(2):83-86.

The efficacy of boric acid in otomycosis: An in vitro study

Karaarslan A., Ozcan KM., Ozcan M.
Dept. Microbiology Univ. of Ankara, Ankara, Turkey. kursatmuratozcan@yahoo.com

OBJECTIVES: Topical antiseptics and antifungal agents are frequently used for the treatment of otomycosis. Topical use of boric acid solution in alcohol is also recommended, and some studies report its clinical efficacy. However, there are no studies in the English literature concerning the in vitro efficacy of boric acid salts on fungi isolated from the ears with otomycosis. In this study, we investigated the in vitro effectiveness of boric acid solutions in distilled water and in ethanol on Aspergillus species and Candida albicans that were isolated from the ears with otomycosis.

MATERIALS AND METHODS: In vitro susceptibilities of Aspergillus species including A. niger, A. fumigatus, A. flavus, A. terreus and C. albicans strains to boric acid solution in distilled water (eau boric), boric acid solution in 70% ethanol (alcohol boric), and to 70% ethanol were investigated using the agar dilution method described by Shubair and Larsen. Concentrations of the media ranged from 0.25% to 4%.

RESULS: Eau boric and alcohol boric were equally effective to inhibit the growth of C. albicans in all concentrations equal to or greater than 0.5% (p>0.05). However, at 0.25%, both solutions were equally ineffective to inhibit the growth of the A s p e r g i l l u s species (p>0.05). At 0.5% concentration, alcohol boric was found significantly more effective against all A s p e r g i l l u s species compared to eau boric (p<0.001). The inhibition of A. niger was significantly more prominent with 1% alcohol boric compared to 1% eau boric (p<0.001). Both solutions were equally effective against all fungi at the concentrations of 2% and 4% (p> 0.05). When compared to alcohol boric and eau boric, ethanol was less effective to inhibit the growth of all fungi at all concentrations (p<0.001).

CONCLUSION: The results of this in vitro study suggest that both alcohol boric and eau boric inhibit the growth of Aspergillus species and C. albicans isolated from the ears with otomycosis. Alcohol boric produces maximal inhibition in lower concentrations compared to eau boric; thus, it may be considered a cost-effective treatment option for otomycosis.