Bactericidal activity of slightly acidic electrolyzed water against the cariogenic bacterium Streptococcus mutans and other oral bacteria

Introduction: Slightly acidic electrolyzed water (SAEW) is sterilizing agent produced by the electrolysis of hydrochloric acid. Because SAEW has been applied to various foods as the disinfectant, SAEW is expected to be used in the medical field. In this study, we evaluated the bactericidal effect of SAEW on various oral bacteria.Methodology: The bactericidal activity of SAEW against cariogenic bacteria, periodontopathogenic bacteria, and antibiotic-resistant bacteria was evaluated.Results: We first examined the effect of SAEW on Streptococcus mutans UA159 with different reaction time or the number of bacterial cells. SAEW showed complete bactericidal activity against up to 10(7) cells within 1 min and even 10 s. Against cariogenic bacteria, periodontopathogenic bacteria, and antibiotic-resistant bacteria, we evaluated the bactericidal effect of SAEW against 10 S. mutans clinical isolates, three periodontopathogenic bacteria, and 18 cephalosporin-resistant Gram-negative bacteria, and we found complete killing against all bacteria. Various dilutions (25%, 50%, and 75%) of SAEW by water still showed complete bactericidal activity, while dilutions by artificial saliva lost the bactericidal activity significantly, with 23.3% bactericidal activity even by 75% SAEW. Storage of SAEW for 7 days at room temperature still showed complete killing activity.Conclusion: Our results demonstrated that SAEW has a high antibacterial effect on oral bacteria, indicating the possibility of clinical use in the dental field such as disinfection of dental devices and oral care.