Extracellular dextran and DNA affect the formation of Enterococcus faecalis biofilms and their susceptibility to 2% chlorhexidine.
BACKGROUND
Enterococcus faecalis is frequently recovered from root-filled teeth with refractory apical periodontitis. The ability of E. faecalis to form a matrix-encased biofilm contributes to its pathogenicity; however, the role of extracellular dextran and DNA in biofilm formation and its effect on the susceptibility of the biofilm to chlorhexidine remains poorly understood.


METHODS
E. faecalis biofilms were incubated on dentin blocks. The effect of a dextran-degrading enzyme (dextranase) and DNase I on the adhesion of E. faecalis to dentin was measured using the colony-forming unit (CFU) counting method. CFU assays and confocal laser scanning microscopy were used to investigate the influence of dextranase and DNase I on the antimicrobial activity of 2% chlorhexidine.


RESULTS
The CFU count assays indicated that the formation of biofilms by E. faecalis was reduced in cells treated with dextranase or DNase I compared with that in untreated cells (P < .05). In addition, we found that treating E. faecalis biofilms with dextranase or DNase I effectively sensitized the biofilms to 2% chlorhexidine (P < .05).


CONCLUSIONS
Both dextranase and DNase I decrease the adhesion of E. faecalis to dentin and sensitized E. faecalis biofilms to 2% chlorhexidine.
Changsha Stomatological Hospital, Changsha, China.
Weilan
W
Li
Hongyan
H
Liu
Qiong
Q
Xu
D000293:Adolescent; D000328:Adult; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002710:Chlorhexidine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000378:metabolism; D003786:Dental Pulp Cavity / Q000382:microbiology; D003804:Dentin / Q000382:microbiology; D003850:Deoxyribonuclease I / Q000494:pharmacology*; D003910:Dextranase / Q000494:pharmacology*; D003911:Dextrans / Q000378:metabolism; D013293:Enterococcus faecalis / Q000187:drug effects*; D005109:Extracellular Matrix / Q000737:chemistry; D006801:Humans; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D012388:Root Canal Irrigants / Q000494:pharmacology*; D055815:Young Adult
D004269:DNA, Bacterial; D003911:Dextrans; D012388:Root Canal Irrigants; D003850:Deoxyribonuclease I; D003910:Dextranase; D002710:Chlorhexidine