pH Required to Kill Enterococcus faecalis in Vitro

Abstract

Enterococcus faecalis tolerates highly alkaline environments, yet the exact pH required for killing E. faecalis is not known. This study tests growth at 0.5 increments from pH 9.5 to 12. Twelve culture tubes were used in each group. Positive growth was measured using turbidity, a visual scale, and a spectrophotometer. At 24 h, growth was observed in all tubes at pH 9.5 and 10. At 48 h, all pH 10.5 tubes showed growth. At 72 h, six of the pH 11 tubes showed growth. After 7 days, five of the remaining pH 11 tubes were positive. No growth occurred in any of the pH 11.5 or pH 12 tubes. Apparently, pH 10.5 to 11.0 retards growth of E. faecalis, whereas no tubes showed growth at pH 11.5 or greater.

Study Comparing the Effectiveness of Chlorhexidine, Calcium Hydroxide and Linezolid Based Medicaments Against Enterococcus Faecalis

“…High pH has a destructive effect on bacterial cell membrane and protein structure [12]. A pH of 10.5 to 11 delays the growth of EF, while, a pH of 11 or more eliminates EF [13,14]. However, CH was the least effective against EF in our study.…”

Enterococcus faecium and Enterococcus faecalis in endodontic infections: antibiotic resistance profile and susceptibility to photodynamic therapy

“…The Gram-positive, facultative aerobe E. faecalis was used as a model organism in this study since it is strongly associated with different forms of periradicular disease, primary endodontic infections as well as persistent infections after failed endodontic treatment [24,60]. A major characteristic of E. faecalis is its ability to withstand very high alkaline conditions pH 11.5 [52,60], which elucidates the importance of alternative or supportive regimens like PDT for treatment of refractory endodontic infections [52].…”

“…A major characteristic of E. faecalis is its ability to withstand very high alkaline conditions pH 11.5 [52,60], which elucidates the importance of alternative or supportive regimens like PDT for treatment of refractory endodontic infections [52].…”

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