Combined Effect of Melittin and DNase on Enterococcus faecalis Biofilms and Its Susceptibility to Sodium Hypochlorite

Abstract

Biofilm communities are tolerant to antimicrobials and difficult to eradicate. This study aimed to investigate the effect of melittin, an antimicrobial peptide, either alone or in combination with deoxyribonuclease (DNase), an inhibitor of extracellular deoxyribonucleic acid (eDNA), against Enterococcus faecalis (E. faecalis) biofilms, and biofilm susceptibility to sodium hypochlorite (NaOCl). Biofilms of E. faecalis were developed in root canals of bovine teeth. The biofilms were treated with distilled water (control), melittin, DNase, or DNase+melittin. The antibiofilm effects of the treatments were analyzed using colony forming unit (CFU) assay, crystal violet staining, confocal laser scanning microscopy (CLSM), and field emission scanning electron microscope (FE-SEM). The susceptibility of DNase+melittin-treated biofilms to NaOCl (0%, 2.5% and 5%) was investigated by the CFU assay. The data were statistically analyzed using one-way analysis of variance, followed by Tukey’s test. A p-value of <0.05 was considered significant. Specimens treated with DNase+melittin showed a more significant decrease in the CFUs, eDNA level, and biofilm formation rate than those treated only with melittin or DNase (p < 0.05). CLSM analysis showed DNase+melittin treatment significantly reduced the volume of biofilms and extracellular polymeric substance compared to either treatment alone (p < 0.05). FE-SEM images showed a high degree of biofilm disruption in specimens that received DNase+melittin. 2.5% NaOCl in specimens pretreated with DNase+melittin showed higher antibacterial activity than those treated only with 5% NaOCl (p < 0.05). This study highlighted that DNase improved the antibiofilm effects of melittin. Moreover, DNase+melittin treatment increased the susceptibility of biofilms to NaOCl. Thus, the complex could be a clinical strategy for safer use of NaOCl by reducing the concentration.

Single DNase or Proteinase Treatment Induces Change in Composition and Structural Integrity of Multispecies Oral Biofilms

“…The authors also indicate that DNase treatment did not affect the maximum biofilm thickness and suggest that EPS matrix in biofilm towers might consist of non-DNA components. Distinct biofilm towers are not observed in our biofilm model; however, this might explain sparse DNase effects on biofilm thickness in other studies [ 27 , 29 , 30 ].…”

“…These results may also indicate, that plain DNase application on matured biofilms might not suffice to inhibit multispecies biofilm formation. Yet, a recently published endodontic study investigated DNase effects alone or in combination with an antimicrobial peptide Melittin on E. faecalis 7 days of biofilm development [ 30 ]. Interestingly, plain DNase application on the matured biofilm resulted in significantly lower bacterial counts and eDNA levels compared to the control biofilms.…”

Evaluation of Physical Properties of Zirconia Suspension with Added Silane Coupling Agent for Additive Manufacturing Processes

“…The sample size was evaluated using G-Power 3.1 software (University of Dusseldorf, Dusseldorf, Germany) [5]. The experimental results were statistically processed by one-way analysis of variance using the SPSS software package (SPSS Version 20.0, SPSS Inc., Chicago, IL, USA), and post tested with the Tukey HSD test.…”

“…Various materials have been used for prostheses in dental clinics, such as titanium, cobalt-chromium, zirconia, and glass ceramics [1][2][3][4][5][6][7]. Among them, ceramic has been widely used and actively investigated, especially with the development of computeraided design/computer-aided manufacturing (CAD/CAM) technology.…”

Antibiofilm activity of phytochemicals against Enterococcus faecalis: A literature review

“…The role of eDNA in protecting E. faecalis biofilms against antimicrobials have been elucidated, since the combination of vancomycin with the DNA‐degrading enzyme (DNase) resulted in >60% reduction in the viability of E. faecalis biofilms, which remain unsusceptible to vancomycin alone (Torelli et al, 2017). Furthermore, E. faecalis biofilms with reduced eDNA content are more susceptible to the killing effects of antimicrobial peptides (Ramaraj et al, 2020) and conventional disinfectants such as sodium hypochlorite (NaOCl; M. K. Yu et al, 2019).…”