Elsevier

Journal of Endodontics

Volume 42, Issue 8, August 2016, Pages 1233-1238
Journal of Endodontics

Basic Research
The Starvation Resistance and Biofilm Formation of Enterococcus faecalis in Coexistence with Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus

https://doi.org/10.1016/j.joen.2016.05.002Get rights and content

Highlights

  • Enterococcus faecalis was more resistant to starvation in a dual-species model than alone.

  • E. faecalis formed more thick and dense biofilms in coexistence with Streptococcus gordonii.

  • E. faecalis formed more thick and dense biofilms in coexistence with Actinomyces viscosus.

  • The multispecies community may be conducive to the survival of E. faecalis.

Abstract

Introduction

Enterococcus faecalis is the most frequently detected species in root canal–treated teeth, and it is able to survive under starvation conditions. However, persistent periapical disease is often caused by multispecies. The aim of this study was to explore the survival of E. faecalis in starvation conditions and biofilm formation with the 4 common pathogenic species.

Methods

A dual-species model of Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus in combination with E. faecalis was established and allowed to grow in phosphate-buffered saline for the examination of starvation survival. Cefuroxime sodium and vancomycin at a concentration of 100 mg/L were added into brain-heart infusion plate agar to count the 2 bacteria separately in the dual species. Scanning electron microscopy was used to observe the dual species and multiple species on the root canal dentin of bovine teeth for 48 hours. A confocal laser scanning microscope was used to show the 4 groups of dual-species biofilms on substrates with glass bottoms for 48 hours.

Results

E. faecalis was more resistant to starvation in coexistence with C. albicans, S. gordonii, A. viscosus, or L. acidophilus, and S. gordonii was completely inhibited in coexistence with E. faecalis. The dual-species biofilm showed that E. faecalis formed thicker and denser biofilms on the root canal dentin and glass slides in coexistence with S. gordonii and A. viscosus than C. albicans and L. acidophilus.

Conclusions

The multispecies community is conducive to the resistance to starvation of E. faecalis and biofilm formation in root canals.

Section snippets

Bacterial Culture

E. faecalis ATCC 29212, C. albicans ATCC 90028, L. acidophilus ATCC 4356, A. viscosus ATCC 15987, and S. gordonii ATCC 10558 were used in this study. The bacteria were streaked from a frozen stock culture onto their respective plates at 37°C for 48 hours. E. faecalis, A. viscosus, and S. gordonii were grown on brain-heart infusion agar (BHI; Difco Laboratories, Detroit, MI) plates; C. albicans were grown on yeast peptone dextrose agar (Difco) plates; and L. acidophilus were grown on de Man,

Antibacterial Assay

Vancomycin and cefuroxime sodium showed different antibacterial activities against E. faecalis, C. albicans, L. acidophilus, A. viscosus, and S. gordonii (Table 1).

Dual-species Resistance to Starvation

At 1 and 2 days of starvation, no significant difference was found between the survival rates of E. faecalis in dual species and alone (P > .05). E. faecalis generated greater resistance to starvation in the presence of C. albicans, S. gordonii, A. viscosus, and L. acidophilus than alone after 4 days, and both showed significant

Discussion

The pathogenic bacteria of root-filled canals with apical periodontitis are frequently restricted to a few gram-positive bacteria, but persistent infection is often caused by polymicrobial action. Although E. faecalis was frequently found in root-filled teeth with apical periodontitis, the strains were not isolated as a monoinfection in most cases 21, 22. Therefore, we explored the dual-species model of E. faecalis and the other 4 common species found in root-filled canals. To quantify either

Acknowledgments

Yan Gao and Xiaoqiong Jiang contributed equally to this work.

We are grateful to Elsevier Language Editing Services for professionally editing this article.

Supported by grants from the Guangdong Natural Science Foundation (no. 2014A030313026).

The authors deny any conflicts of interest related to this study.

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