Antibacterial Activity of 2-Hydroxyisocaproic Acid (HICA) Against Obligate Anaerobic Bacterial Species Associated With Periodontal Disease

Topical antiseptics are used to assist and further increase the effect of mechanical biofilm eradication and to potentially prevent new biofilm formation in periodontal treatment. This is of importance in treatment-resistant infections with 10% prevalence of all periodontitis cases to avoid the need for antibiotic therapy. The purpose of this study was to evaluate the antimicrobial activity of DL-2-hydroxyisocaproic acid on human pathogenic obligate anaerobic bacteria related to periodontitis. In this study antimicrobial activity of 2-hydroxyisocaproic acid was observed against 14 bacterial reference strains and clinical isolates of obligate anaerobic bacterial species using a microdilution method in 1.25 to 160 mg/mL concentrations of 2-hydroxyisocaproic acid. The 11 strains of bacteria included in this study are typically associated with periodontal disease; Porphyromonas gingivalis, Fusobacterium nucleatum, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, and Parvimonas micra. Three strains of Cutibacterium acnes, normally associated with skin diseases, were tested for comparison. 90% inhibitory concentration was determined at 48 hours and minimum bactericidal concentration was determined after 72 hours incubation. The 2-hydroxyisocaproic acid was bactericidal at ⩾160 mg/mL for all isolates tested. The reference strain of T. forsythia, and the reference strain and the clinical isolates of C. acnes were the most tolerant ones. The reference strains and clinical isolates of F. nucleatum and A. actinomycetemcomitans were killed at ⩾40 mg/mL concentration. In conclusion, topical use of 2-hydroxyisocaproic acid could eventually be a well-tolerated and useful method in the therapy of patients with difficult-to-treat periodontal disease or other superficial infections to avoid unnecessary antibiotic use and the emergence of antibiotic resistance.