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.
Highlights
The persistence of microbes in the root canal system often leads to endodontic failures [1].Among these, Enterococcus faecalis (E. faecalis), a gram-positive facultative anaerobic cocci, is one of the Materials 2020, 13, 3740; doi:10.3390/ma13173740 www.mdpi.com/journal/materialsMaterials 2020, 13, 3740 predominant bacteria associated with failed endodontic cases and can adapt to harsh environmental conditions by forming antimicrobial-resistant biofilms [1]
A significant reduction in Extracellular deoxyribonucleic acid (eDNA) was noted in specimens treated with melittin, DNase, and DNase+melittin (p < 0.05), compared to the control
This present study evaluated the efficacy of melittin against E. faecalis biofilms for the first time
Summary
Materials 2020, 13, 3740 predominant bacteria associated with failed endodontic cases and can adapt to harsh environmental conditions by forming antimicrobial-resistant biofilms [1]. Bacteria within biofilms are more resistant to antibacterial agents than their planktonic forms [4]. This is because the bacteria encased in biofilms are protected by a complex matrix of extracellular polymeric substances (EPS), which provide mechanical stability to the biofilms and prevent the entry/action of antimicrobials [5]. Extracellular deoxyribonucleic acid (eDNA), an important component of the extracellular matrix, is responsible for maintaining the stability of biofilms and preventing the penetration of antimicrobial agent through the matrix encased biofilms [6]. Deoxyribonuclease (DNase), an inhibitor of the eDNA, has been shown to digest eDNA in biofilms and reduce the adherence of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
