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Conference Paper: Molecular Detection of Virulence Determinants in Enterococcus faecalis Isolates
| Title | Molecular Detection of Virulence Determinants in Enterococcus faecalis Isolates |
|---|---|
| Authors | |
| Issue Date | 2018 |
| Citation | 96th General Session & Exhibition of the IADR and IADR Pan European Regional Congress, London, UK, 22-25 July 2018 How to Cite? |
| Abstract | Objectives: Enterococcus faecalis is the most frequently isolated bacterium from root canals of teeth that exhibit chronic apical periodontitis refractory to endodontic treatment. Various survival and virulence mechanisms contribute to this recalcitrance, including its ability to invade dentinal tubules, resist harsh environmental conditions, and form strong biofilms. Regulation of virulence factors in E. faecalisr equires the activation of density-dependent gene expression, mediated through quorum-sensing systems (QS). The Fsr-QS controls proteases that contribute to virulence by degrading host tissues. The cytolysin-QS regulates the expression of a pore-forming toxin, displaying bactericidal and hemolytic activities. Consequently, inhibition of QS-systems represents an attractive way of combating E. faecalis infections without exerting a pressure to select drug-resistant strains from the population. The objective of this study was to characterize clinical strains of E. faecalis for the QS-system associated genes and virulence factor production.
Methods: Ten clinical strains of E. faecalis were isolated from root canals with persistent infection. Molecular screening of the clinical samples was performed for genes encoding virulence factors and QS-systems. The production of gelatinase and hemolysin was also investigated.
Results: The percentage of E. faecalis isolates harboring virulence and QS genes were: gelE and luxS (100%); cylA (88.9%); agg (55.6%); and fsrA (11.1%). All strains positive for cylA gene showed ß-hemolytic activity. Gelatinase activity was detected in all isolates including strains with a chromosomal deletion containing the fsr-gene cluster, suggesting a different gene-regulatory system for gelE. The presence of agg gene indicates their potential for genetic exchange by conjugation, contributing to the dissemination of antibiotic resistance genes to bacteria inhabiting the oral cavity.
Conclusions: The presence of virulence determinants in E. faecalis strains may be significant in the evolution of oral pathogenic E. faecalis strains found in persistent endodontic infections. |
| Description | Oral Session 274 - Endodontic Pathogens, Presentation No. 1774 |
| Persistent Identifier | http://hdl.handle.net/10722/263502 |
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Neelakantan, P | - |
| dc.contributor.author | Selvabaskaran, AM | - |
| dc.contributor.author | Levesque, CM | - |
| dc.date.accessioned | 2018-10-22T07:40:00Z | - |
| dc.date.available | 2018-10-22T07:40:00Z | - |
| dc.date.issued | 2018 | - |
| dc.identifier.citation | 96th General Session & Exhibition of the IADR and IADR Pan European Regional Congress, London, UK, 22-25 July 2018 | - |
| dc.identifier.uri | http://hdl.handle.net/10722/263502 | - |
| dc.description | Oral Session 274 - Endodontic Pathogens, Presentation No. 1774 | - |
| dc.description.abstract | Objectives: Enterococcus faecalis is the most frequently isolated bacterium from root canals of teeth that exhibit chronic apical periodontitis refractory to endodontic treatment. Various survival and virulence mechanisms contribute to this recalcitrance, including its ability to invade dentinal tubules, resist harsh environmental conditions, and form strong biofilms. Regulation of virulence factors in E. faecalisr equires the activation of density-dependent gene expression, mediated through quorum-sensing systems (QS). The Fsr-QS controls proteases that contribute to virulence by degrading host tissues. The cytolysin-QS regulates the expression of a pore-forming toxin, displaying bactericidal and hemolytic activities. Consequently, inhibition of QS-systems represents an attractive way of combating E. faecalis infections without exerting a pressure to select drug-resistant strains from the population. The objective of this study was to characterize clinical strains of E. faecalis for the QS-system associated genes and virulence factor production. Methods: Ten clinical strains of E. faecalis were isolated from root canals with persistent infection. Molecular screening of the clinical samples was performed for genes encoding virulence factors and QS-systems. The production of gelatinase and hemolysin was also investigated. Results: The percentage of E. faecalis isolates harboring virulence and QS genes were: gelE and luxS (100%); cylA (88.9%); agg (55.6%); and fsrA (11.1%). All strains positive for cylA gene showed ß-hemolytic activity. Gelatinase activity was detected in all isolates including strains with a chromosomal deletion containing the fsr-gene cluster, suggesting a different gene-regulatory system for gelE. The presence of agg gene indicates their potential for genetic exchange by conjugation, contributing to the dissemination of antibiotic resistance genes to bacteria inhabiting the oral cavity. Conclusions: The presence of virulence determinants in E. faecalis strains may be significant in the evolution of oral pathogenic E. faecalis strains found in persistent endodontic infections. | - |
| dc.language | eng | - |
| dc.relation.ispartof | General Session & Exhibition of the IADR and IADR Pan European Regional Congress | - |
| dc.title | Molecular Detection of Virulence Determinants in Enterococcus faecalis Isolates | - |
| dc.type | Conference_Paper | - |
| dc.identifier.email | Neelakantan, P: prasanna@hku.hk | - |
| dc.identifier.authority | Neelakantan, P=rp02214 | - |
| dc.identifier.hkuros | 293557 | - |
| dc.publisher.place | London, UK | - |