A study of the antibacterial effect of boric acid

Abstract

The antibacterial effect of boric acid, especially as it relates to dermatological infectious disease, was studied. Boric acid was once one of the most important reagents applied to the treatment of dermatological infectious diseases. Since the 19 th century it was widely used and thought to be one of the most effective antibacterial reagents. Since 1950, though, many side effects of boric acid have been strongly pointed out, including accidental death. As a result, use of boric acid was stopped in spite of its usefulness. In this study, we examined the antibacterial effect of boric acid and obtained very interesting results. The growth of all bacteria and fungi tested here was completely inhibited by 1%(wt/vol) of boric acid added to the media. MICs were distributed between 0.125%, to 1%, and bacteria belonging to the same species showed similar MICs. Compared with 16 years ago, the antibacterial effect against Staphylococcus aureus has not changed at all, and there have been no differences in the MICs between methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). This shows that MRSA might have difficulty in acquiring resistance to boric acid. The effect on MRSA suggests that this formerly used reagent might be able to be used to treat infection with MRSA. This study suggests that the antibacterial effect of boric acid should be reevaluated, and that use at appropriate dosages may be beneficial in treating bacterial skin infections.