The aim of this study was to investigate the acid- and alkali-resistance and its biochemical mechanism of endodontic pathogen Enterococcus faecalis and to compare with those of other oral streptococci. The acid- and alkali-resistance of each strain was estimated as follows: 1) the growth ability in the complex medium, 2) the cell durability to leakage of pre-loaded BCECF and 3) the intracellular pH (pHin) stability. The results indicate that E. faecalis is not only acid-resistant similar to Streptococcus mutans but more alkali-resistant than S. mutans. This study suggests that the acid- and alkali-resistance of E. faecalis is derived from the membrane durability and impermeability against acid and alkali. Such characteristics of E. faecalis could be the reasons why E. faecalis is frequently isolated from both acidic caries lesions and persistent infected root canals where calcium hydroxide medicaments are ineffective.
ASJC Scopus subject areas