Bactericidal activity of phosphoric acid, citric acid, and EDTA solutions against Enterococcus faecalis

Objectives The objectives of this study were to evaluate the minimal bactericidal concentration (MBC) for Enterococcus faecalis of phosphoric acid, citric acid, and ethylenediaminetetraacetic acid (EDTA) solutions, and to determine the contact time required for 2.5% and 5% phosphoric acid, 10% and 25% citric acid, and 17% EDTA to exert bactericidal activity. Study design Bactericidal activity was tested by means of the dilution neutralization method in accordance with BS-EN-1040:2005 norm, using contact times of 0.5 to 60 minutes. Results The MBCs of citric and phosphoric acid were 20% and 2.5%, respectively. EDTA solution lacks bactericidal activity, even after 60 minutes of contact. The 2.5% and 5% phosphoric acid solutions required 5- and 3-minute contact times, and the 10% and 25% citric acid solutions required 10- and 3-minute contact times, respectively. Conclusions Phosphoric acid revealed bactericidal activity against E. faecalis and required less time than citric acid to exert its activity.