Enterococci in human periodontitis

Prevalence of Enterococcus species in adults with periodontal health or with periodontitis: a systematic review

The aim of this study was to evaluate the prevalence of Enterococcus species in the mouth of adults with periodontal health and periodontitis. A systematic search was made in databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The search for articles was conducted in Medline/PubMed, Latin American and Caribbean Health Sciences Literature Database (LILACS), Cochrane Library, Scopus, Embase, Web of Science databases and in the System of Information on Grey Literature in Europe (SINGLE) and included articles published in English up to April 25th, 2021. Observational studies in humans with and without periodontitis were evaluated to identify the prevalence of Enterococcus species. Articles that met the inclusion criteria were analyzed and classified to determine the quality rating in good, fair, and poor. A new detailed checklist for quality assessment was developed based on the information required for applicable data extraction in reviews. The study design, sample size, demographic data, periodontal clinical parameters, microbial analysis method, biological sample, prevalence of Enterococcus spp., and correlations with periodontal clinical parameters were assessed. After screening and full-text reading, 8 articles met the inclusion criteria. All selected studies showed a significantly higher prevalence of Enterococcus spp. in patients with periodontitis compared with periodontally healthy patients. Thus, the present systematic review suggests that the prevalence of Enterococcus faecalis in the mouth of periodontitis individuals is higher than that of periodontally healthy individuals.

Newly identified pathogens in periodontitis: evidence from an association and an elimination study

We assessed the level of evidence for the presence of new periodontal pathogens by (i) comparing the occurrence of non-classical periodontal taxa between healthy vs. periodontitis patients (Association study); (ii) assessing the modifications in the prevalence and levels of these species after treatments (Elimination study). In the Association study, we compared the prevalence and levels of 39 novel bacterial species between periodontally healthy and periodontitis patients. In the Elimination study, we analyzed samples from periodontitis patients assigned to receive scaling and root planing alone or with metronidazole+ amoxicillin TID/ 14 days. Levels of 79 bacterial species (39 novel and 40 classic) were assessed at baseline, 3 and 12 months post-therapy. All samples were analyzed using Checkerboard DNA-DNA hybridization. Out of the 39 novel species evaluated, eight were categorized as having strong and four as having moderate association with periodontitis. Our findings suggest strong evidence supporting Lancefieldella rimae, Cronobacter sakazakii, Pluralibacter gergoviae, Enterococcus faecalis, Eubacterium limosum, Filifactor alocis, Haemophilus influenzae, and Staphylococcus warneri, and moderate evidence supporting Escherichia coli, Fusobacterium necrophorum, Spiroplasma ixodetis, and Staphylococcus aureus as periodontal pathogens. These findings contribute to a better understanding of the etiology of periodontitis and may guide future diagnostic and interventional studies.

Antimicrobial Chemotherapy for Recalcitrant Severe Human Periodontitis

This study evaluated a combined systemic and topical anti-infective periodontal treatment of 35 adults who had experienced ongoing periodontal breakdown following conventional surgical periodontics. The prescribed anti-infective therapy, based on microbiological testing, consisted of a single course of metronidazole plus ciprofloxacin (23 patients), metronidazole plus amoxicillin/clavulanic acid (10 patients), and metronidazole plus ciprofloxacin followed by metronidazole plus amoxicillin/clavulanic acid (2 patients). In addition, the study patients received 0.1% povidone-iodine subgingival disinfection during non-surgical root debridement and daily patient administered oral irrigation with 0.1% sodium hypochlorite. At 1 and 5 years post-treatment, all study patients showed gains in clinical periodontal attachment with no further attachment loss, and significant decreases in pocket probing depth, bleeding on probing, and subgingival temperature. The greatest disease resolution occurred in patients who at baseline harbored predominantly major periodontal pathogens which post-antibiotics became non-detectable and substituted by non-periodontopathic viridans streptococci. The personalized and minimally invasive anti-infective treatment regimen described here controlled periodontitis disease activity and markedly improved the clinical and microbiological status of the refractory periodontitis patients.

The Regulations of Essential WalRK Two-Component System on Enterococcus faecalis

Enterococcus faecalis (E. faecalis) is a Gram-positive, facultative anaerobic bacterium that is highly adaptable to its environment. In humans, it can cause serious infections with biofilm formation. With increasing attention on its health threat, prevention and control of biofilm formation in E. faecalis have been observed. Many factors including polysaccharides as well as autolysis, proteases, and eDNA regulate biofilm formation. Those contributors are regulated by several important regulatory systems involving the two-component signal transduction system (TCS) for its adaptation to the environment. Highly conserved WalRK as one of 17 TCSs is the only essential TCS in E. faecalis. In addition to biofilm formation, various metabolisms, including cell wall construction, drug resistance, as well as interactions among regulatory systems and resistance to the host immune system, can be modulated by the WalRK system. Therefore, WalRK has been identified as a key target for E. faecalis infection control. In the present review, the regulation of WalRK on E. faecalis pathogenesis and associated therapeutic strategies are demonstrated.

Prevalence and Antibiotic Susceptibility Trends of Selected Enterobacteriaceae, Enterococci, and Candida albicans in the Subgingival Microbiota of German Periodontitis Patients: A Retrospective Surveillance Study

The periodontal microbiota is ecologically diverse and may facilitate colonization by bacteria of enteric origin (Enterobacteriaceae, Enterococci) and co-infections with Candida albicans, possibly producing subgingival biofilms with high antimicrobial tolerance. This retrospective surveillance study followed periodontitis-associated superinfection profiles in a large patient sample. From 2008 to 2015, biofilm samples from deep periodontal pockets were collected from a total of 16,612 German adults diagnosed with periodontitis. The presence of selected Enterobacteriaceae, Enterococci, and Candida albicans was confirmed in overnight cultures. Antimicrobial susceptibility of these clinical isolates was tested by disk diffusion with antibiotics routinely used for treatment of oral infections, e.g., amoxicillin (AML), amoxicillin/clavulanic acid (AMC), doxycycline (DO), and ciprofloxacin (CIP). The mean annual prevalence of patients harboring Enterobacteriaceae in periodontal plaques was 11.5% in total and ranged from 2.5% for Enterobacter cloacae to 3.6% for Klebsiella oxytoca, 1.1% for Klebsiella pneumoniae, 2.8% for Serratia marcescens, and 1.5% for Serratia liquefaciens. In comparison, the mean detection rates for microbiota typically found in the oral cavity were higher, e.g., 5.6% for Enterococcus spp. and 21.8% for Candida albicans. Among the Enterobacteriaceae, species harboring intrinsic resistance to AML (Enterobacter spp., Klebsiella spp., Serratia spp.) were predominant. Non-susceptibility to AMC was observed for Serratia spp. and Enterobacter cloacae. By contrast, Enterococcus spp. only showed non-susceptibility to DO and CIP. Trends for increasing resistance were found to AML in Serratia liquefaciens and to DO in Enterococcus spp. Trend analysis showed decreasing resistance to AMC in Serratia liquefaciens and Klebsiella oxytoca; and to DO in Serratia marcescens, liquefaciens, and Enterobacter cloacae. This study confirms the low but consistent presence of Enterobacteriaceae and Enterococci among the subgingival microbiota recovered from periodontitis specimen. Although their pathogenetic role in periodontal lesions remains unclear, their presence in the oral cavity should be recognized as a potential reservoir for development and spread of antibiotic resistance in light of antibiotic usage in oral infections.

Study of the ultrastructure of Enterococcus faecalis and Streptococcus mutans incubated with salivary antimicrobial peptides

OBJECTIVES

Enterococcus faecalis has been associated with root canal infections, while Streptococcus mutans has a central role in the etiology of dental caries. One of the main reasons of endodontic failure has been associated to the presence of E. faecalis and the formation of biofilms. S. mutans inhabits the oral cavity, specifically the dental plaque, which is a multispecies biofilm formed on the hard surfaces of the tooth. The biofilm formation is the main factor determining the pathogenicity of numerous bacteria. Natural antimicrobial peptides in the saliva protect against pathogenic bacteria and biofilms. The aim of this study was to assess the ultrastructural damage induced by salivary peptides in bacteria involved in biofilms has not been previously studied.

MATERIAL AND METHODS

Enterococcus faecalis and S. mutans incubated with cystatin C, chromogranin A, or histatin 5 were morphologically analyzed and counted. The ultrastructural damage was evaluated by transmission electron microscopy (TEM).

RESULTS

A decrease in bacterial numbers was observed after incubation with cystatin C, chromogranin A, or histatin 5, compared to the control group (P <  0.001). Ultrastructural damage in E. faecalis and S. mutans incubated with salivary peptides was found in the cell wall, plasma membrane with a decreased distance between the bilayers, a granular pattern in the cytoplasm, and pyknotic nucleoids.

CONCLUSIONS

This study demonstrated that salivary peptides exert antibacterial activity and induce morphological damage on E. faecalis and S. mutans. Knowledge on the ultrastructural damage inflicted by salivary antimicrobial peptides on two important bacteria causing dental caries and root canal infections could aid the design of new therapeutic approaches to facilitate the elimination of these bacteria.

Antimicrobial susceptibility and virulence of Enterococcus spp. isolated from periodontitis-associated subgingival biofilm

BACKGROUND

This study evaluated the prevalence, virulence and antimicrobial susceptibility of enterococci isolated from the subgingival microbiota of patients with different periodontal status.

METHODS

Subgingival biofilm was obtained from individuals with periodontal health (PH) (n = 139), gingivitis (n = 103), and periodontitis (n = 305) and cultivated on selective media. Isolated strains were identified by mass spectrometry. Antimicrobial sensitivity was determined by disk diffusion, virulence genes by polymerase chain reaction, and the subgingival microbiota by checkerboard. Differences among groups were assessed by Kruskal-Wallis, Mann-Whitney, and Chi-square tests.

RESULTS

Enterococcus spp. were isolated from 7.4% of all samples; 53.7% were Enterococcus faecalis. They were more prevalent in periodontitis (9.8%) and gingivitis (7.8%) than PH (2.2%; P <0.05), but no differences among stages of disease severity were observed. High rates of low susceptibility/resistance (>64%) to at least one antimicrobial were observed. Predominant virulence factors included ace (64.3%), asa (39.3%), and esp (35.7%). Fusobacterium nucleatum was prevalent in the subgingival microbiota of enterococci+ individuals, whereas Dialister pneumosintes was found in low frequency in patients with bopD+ enterococci. Oral streptococci were prevalent (>70%) in patients carrying enterococci susceptible to doxycycline (P <0.05), usually bopD- and esp- (P <0.01).

CONCLUSIONS

E. faecalis is increased in periodontitis-associated biofilm. Oral enterococci carry virulence genes and express resistance to some antibiotics commonly used in dentistry, such as ciprofloxacin and erythromycin. Specific subgingival taxa are associated with oral enterococci, suggesting they may interact with species of the dysbiotic periodontitis biofilm, constituting a potential source of factors to tissue destruction, antibiotic resistance dissemination, and poor response to periodontal therapy.

Characterization of φEf-vB1 prophage infecting oral Enterococcus faecalis and enhancing bacterial biofilm formation

Introduction. Enterococcus faecalis is a facultative, anaerobic, opportunistic pathogen associated with medical and dental diseases. Bacterial phenotypic traits and pathogenesis are often influenced by lysogeny.Aim. The aim of this study was to characterize both the morphology and complete genome sequences of induced prophages purified from E. faecalis clinical isolates.Methodology. E. faecalis isolates were recovered from the roots of teeth of patients attending an endodontic clinic. The morphological features of isolated phage were characterized using transmission electron microscopy (TEM). DNA sequencing was performed using the Illumina MiSeq platform.Results. TEM indicated that the isolated φEf-vB1 prophage belongs to the family Siphoviridae. The φEf-vB1 prophage was stable over a wide range of temperatures and pH. Sequencing of φEf-vB1 DNA revealed that the phage genome is 37 561 bp in length with a G+C content of 37.6mol% and contained 53 ORFs. Comparison with previously predicted prophage genomes using blast revealed that φEf-vB1 has a high sequence similarity to previously characterized phage genomes. The lysogenic E. faecalis strain exhibited a higher biofilm formation capacity relative to the non-lysogenic strain.Conclusion. The current findings highlight the role of lysogeny in modification of E. faecalis properties and reveal the potential importance of prophages in E. faecalis biology and pathogenesis.

Genotype, biofilm formation ability and specific gene transcripts characteristics of endodontic Enterococcus faecalis under glucose deprivation condition

OBJECTIVE

To study the relationship between the specific gene and biofilm formation ability of seven wild type Enterococcus faecalis (E. faecalis) under glucose deprivation conditions.

DESIGN

Wild type E. faecalis (3RC, 5RC, 25RC, 31RC, 33RC, 37RC, 58RC) extracted from the teeth with persistent apical periodontitis were cultured under glucose deprivation conditions and then resequenced. The biofilm formation ability was compared using primary adherence assay, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The transcriptional level of biofilm formation-related genes (ace, gelE, efa, esp and fsrB) were detected.

RESULTS

Genomic resequencing showed that 3RC and 58RC (Class B) were similar, while 5RC, 25RC, 31RC, 33RC and 37RC (Class A) were similar. Based on primary adherence assay, CLSM and SEM results, biofilm formation ability of Class B strains was lower, while Class A strains were higher when compared with control group (0.25 % glucose). Furthermore, compared with control group (0.25 % glucose), the transcriptional levels of ace, efa and fsrB genes were upregulated in all strains; the transcriptional levels of gelE were downregulated in Class B strains, upregulated in Class A strains; the transcriptional levels of esp of Class B strains were downregulated, while upregulated in 25RC, 31RC and 37RC (Class A), and not observed in 5RC and 33RC.

CONCLUSION

The genotypes of wild type E. faecalis of different persistent periapical periodontitis teeth are different. The genotype differences and the transcription levels of related virulence genes (ace, gelE, efa, esp and fsrB) are related to the biological phenotype.

The prevalence and impact of lysogeny among oral isolates of Enterococcus faecalis

Bacterial phenotypic properties are frequently influenced by the uptake of extrachromosomal genetic elements, such as plasmids and bacteriophage genomes. Such modifications can result in enhanced pathogenicity due to toxin production, increased toxin release, altered antigenicity, and resistance to antibiotics. In the case of bacteriophages, the phage genome can stably integrate into the bacterial chromosome as a prophage, to produce a lysogenic cell. Oral enterococcal strains have been isolated from subgingival plaque and the root canals of endodontically-treated teeth that have failed to heal. Previously, we isolated a bacteriophage, phage ɸEf11, induced from a lysogenic Enterococcus faecalis strain recovered from the root canal of a failed endodontic case. PCR analysis using phage ɸEf11-specific oligonucleotide primers, disclosed that lysogens containing ɸEf11 prophages were commonly found among oral E. faecalis strains, being detected in 19 of 61 (31%) strains examined. Furthermore, in comparison to an isogenic cured strain, cultures of a lysogen harboring an ɸEf11 prophage exhibited altered phenotypic characteristics, such as increased persistence at high density, enhanced biofilm formation, and resistance to a bacteriophage lytic enzyme. From these results we conclude that lysogeny is common among oral E. faecalis strains, and that it alters properties of the lysogenic cell.

Emergence of multidrug resistance and extensive drug resistance among enterococcal clinical isolates in Egypt

Introduction

Enterococci commonly inhabit the gastrointestinal tract of both human and animals; however, they have emerged as a leading cause of several infections with substantial morbidity and mortality. Their ability to acquire resistance combined with intrinsic resistance to various antimicrobials makes treatment of enterococcal infections challenging.

Materials and methods

The aim of the study was to evaluate the antimicrobial resistance pattern, and assess the prevalence of multidrug resistance (MDR) and extensive drug resistance (XDR) among enterococcal isolates, collected from different clinical sources, in Mansoura University Hospitals, Egypt.

Results

Antibiotic sensitivity testing revealed elevated levels of resistance among enterococcal clinical isolates (N=103). All E. faecium (N=32) and 74.6% of E. faecalis isolates(N=71) were MDR, while two E. faecalis and four E. faecium isolates were XDR. High level gentamicin resistance was detected in 79.6%, most of them carried the aac(6’)-Ie-aph(2’’)-Ia gene. High level streptomycin resistance was seen in 36.9%, of which 52.6% carried the ant(6’)-Ia gene. Resistance to macrolides and lincosamides were mediated by ermB (92.2%) and msrA/B (42.7%). tetK, tetL, andtetM genes were detected among tetracyclines resistant isolates. Resistance to vancomycin was detected in 15.5%, where vanB and vanC₁ gene clusters were detected in VRE isolates. Ten isolates (9.7%) were resistant to linezolid, eight of which harbored the optrA gene. Vancomycin and linezolid resistant enterococci were more likely to exhibit strong/moderate biofilm formation than vancomycin and linezolid sensitive ones.

Conclusion

Elevated levels of resistance to different classes of antimicrobial agents and emergence of MDR and XDR strains pose a major threat with limited therapeutic options for infections caused by this emerging pathogen.

Diversity and functional analysis of salivary microflora of Indian Antarctic expeditionaries

Introduction: The human oral microbiota continues to change phenotype by many factors (environment, diet, genetics, stress, etc.), throughout life with a major impact on human physiology, psychology, metabolism and immune system. Amongst one such factor with unique and extreme environmental conditions is Antarctica. The sea voyage to Antarctica has many risks than at station for expedition members. In this study, we investigated the influence of Antarctic sea voyage and stay at the Indian Antarctic station Maitri, on the health of Indian expedition members by using a metagenomic approach to explore oral biodiversity. Methods: Saliva samples were collected from 12 expedition members, at 3 different time points viz. before the start of the ship voyage, after the completion of the voyage and at the end of the stay at Antarctica. Samples were analyzed for whole genome and 16S rRNA sequencing. Result: The oral microbial diversity of the expedition members was significantly changed, during the days of sailing and after the stay at Antarctica. The oral microbiota comprised mainly of the phyla Firmicutes (46%, 29% & 36%); Proteobacteria (40%, 48%, & 44%), Bacteroidetes (10%, 22%, &14%), Fusobacterium and Actinobacteria (5%-1%) and Unclassified (17%, 25% & 23%), at three time points, respectively. Further, the differential analysis of microbes across all the phyla revealed 89, 157 and 157 OTUs genera. The altered microbiota indicated changes in amino acid, lipid and carbohydrate metabolism. Conclusion: Study suggests that understanding the compositional and functional differences in the oral microbiota of Antarctic expedition members, can lay the foundation to relate these differences to their health status. It will further demonstrate the need for providing improved management during ship voyage and stay in Antarctica.

Antibiotics/antimicrobials: systemic and local administration in the therapy of mild to moderately advanced periodontitis

This review gives an update of the current scientific evidence on the efficacy of the adjunctive use of systemic and local antibiotics/antimicrobials in the treatment of periodontitis. In particular, it addresses whether their use can improve the results of nonsurgical mechanical therapy in mild-to-moderate forms of the disease. Large numbers of randomized clinical trials and systematic reviews with meta-analyses have clearly established that adjunctive systemic antibiotics, combined with mechanical debridement, offer clinical improvements additional to those obtained with scaling and root planing alone. These effects are more pronounced in aggressive periodontitis and in initially deep pockets, whereas more limited additional improvements, of 0.3 mm for additional pocket reduction and 0.2 mm for additional clinical attachment gain, have been documented for moderately deep sites (4-6 mm) in patients with chronic periodontitis. The marginal clinical benefit in patients with moderate disease has to be balanced against possible side effects. Notably, it has to be realized that an increasing number of warnings have been articulated against the unrestricted use of antibiotics in treating periodontal diseases because of the emerging global public health issue of bacterial resistance. The effects of the adjunctive local administration of antimicrobials have also been very well documented in several systematic reviews. Overall, in persistent or recurrent localized deep sites, the application of antimicrobials by sustained-delivery devices may offer a benefit of an additional 0.4 mm in pocket depth reduction and 0.3 mm in clinical attachment level gain. In conclusion, the slight additional benefits of adjunctive antimicrobials, which were shown for moderate forms of periodontitis, have to be balanced against their side effects and therefore their prescription should be limited as much as possible.

Effect of a genetically engineered bacteriophage on Enterococcus faecalis biofilms

OBJECTIVE

Enterococcus faecalis is a Gram-positive, facultative anaerobic bacterium that is associated with failed endodontic cases and nosocomial infections. E. faecalis can form biofilms, penetrate dentinal tubules and survive in root canals with scarce nutritional supplies. These properties can make E. faecalis resistant to conventional endodontic disinfection therapy. Furthermore, treatment may be complicated by the fact that many E. faecalis strains are resistant to antibiotics. A potential alternative to antibiotic therapy is phage therapy. ϕEf11 is a temperate phage that infects strains of E. faecalis. It was previously sequenced and genetically engineered to modify its properties in order to render it useful as a therapeutic agent in phage therapy. In the current study, we have further genetically modified the phage to create phage ϕEf11/ϕFL1C(Δ36)PnisA. The aim of this study was to evaluate the efficacy of bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA, to disrupt biofilms of two Enterococcus faecalis strains: JH2-2 (vancomycin-sensitive) and V583 (vancomycin-resistant).

METHODS

24h static biofilms of E. faecalis strains JH2-2(pMSP3535 nisR/K) and V583 (pMSP3535nisR/K), formed on cover slips, were inoculated with bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA. After 24 and 48h incubation, the bacterial biomass was imaged by confocal microscopy and viable cells were quantified by colony forming unit measurement.

RESULTS

The results showed a 10-100-fold decrease in viable cells (CFU/biofilm) after phage treatment, which was consistent with comparisons of treated and untreated biofilm images visualized as max projections of the Z-series.

CONCLUSION

The biomass of both vancomycin-sensitive and vancomycin-resistant E. faecalis biofilms is markedly reduced following infection by bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA.

Comparative Evaluation of Ciprofloxacin Levels in GCF and Plasma of Chronic Periodontitis Patients: Quasi Experimental Study

INTRODUCTION

For any antimicrobial approach to be successful in periodontal therapy, it is important that the antimicrobial agent targets the sub-gingival biofilm by attaining sufficient concentration at the sub-gingival site.

AIM

The purpose of the present study was to determine and compare the concentrations of ciprofloxacin present in Gingival Crevicular Fluid (GCF) and plasma after its systemic administration.

MATERIALS AND METHODS

A total of 20 subjects, in the age group of 30-60 years satisfying the inclusion and exclusion criteria, were chosen from the outpatient Department of Periodontology, Government Dental College and Hospital, Hyderabad and consent was obtained. Subjects were put on oral ciprofloxacin therapy (Baycip, Bayer Corporation) of 500mg twice daily doses for five days to establish steady state tissue levels of the agent. GCF and serum samples were collected at the 72(nd) hour after the first dose of ciprofloxacin and were compared using unpaired t test.

RESULTS

The mean gingival index value of the subjects was 1.8 ± 0.59 and the mean probing depth of the subjects taken in the study was 5.724 ± 0.47mm. The results of this study showed that ciprofloxacin concentrations were significantly higher (p<0.001) in GCF than in plasma.

CONCLUSION

Results from the present study and those from the earlier studies clearly indicate the ciprofloxacin's ability to reach and concentrate in infected periodontal sites via GCF. This property of ciprofloxacin may be useful for eradication of periodontal pathogens, thus improving the outcome of periodontal therapy.

Quantitative Molecular Detection of 19 Major Pathogens in the Interdental Biofilm of Periodontally Healthy Young Adults

In oral health, the interdental spaces are a real ecological niche for which the body has few or no alternative defenses and where the traditional daily methods for control by disrupting biofilm are not adequate. The interdental spaces are the source of many hypotheses regarding their potential associations with and/or causes of cardiovascular disease, diabetes, chronic kidney disease, degenerative disease, and depression. This PCR study is the first to describe the interdental microbiota in healthy adults aged 18–35 years-old with reference to the Socransky complexes. The complexes tended to reflect microbial succession events in developing dental biofilms. Early colonizers included members of the yellow, green, and purple complexes. The orange complex bacteria generally appear after the early colonizers and include many putative periodontal pathogens, such as Fusobacterium nucleatum. The red complex (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) was considered the climax community and is on the list of putative periodontal pathogens. The 19 major periodontal pathogens tested were expressed at various levels. F. nucleatum was the most abundant species, and the least abundant were Actinomyces viscosus, P. gingivalis, and Aggregatibacter actinomycetemcomitans. The genome counts for Eikenella corrodens, Campylobacter concisus, Campylobacter rectus, T. denticola, and Tannerella forsythensis increased significantly with subject age. The study highlights the observation that bacteria from the yellow complex (Streptococcus spp., S. mitis), the green complex (E. corrodens, Campylobacter gracilis, Capnocytophaga ochracea, Capnocytophaga sputigena, A. actinomycetemcomitans), the purple complex (Veillonella parvula, Actinomyces odontolyticus) and the blue complex (A. viscosus) are correlated. Concerning the orange complex, F. nucleatum is the most abundant species in interdental biofilm. The red complex, which is recognized as the most important pathogen in adult periodontal disease, represents 8.08% of the 19 bacteria analyzed. P. gingivalis was detected in 19% of healthy subjects and represents 0.02% of the interdental biofilm. T. forsythensis and T. denticola (0.02 and 0.04% of the interdental biofilm) were detected in 93 and 49% of healthy subjects, respectively. The effective presence of periodontal pathogens is a strong indicator of the need to develop new methods for disrupting interdental biofilm in daily oral hygiene.

Enterococcus faecalis from Food, Clinical Specimens, and Oral Sites: Prevalence of Virulence Factors in Association with Biofilm Formation

Enterococci have gained significance as the cause of nosocomial infections; they occur as food contaminants and have also been linked to dental diseases. E. faecalis has a great potential to spread virulence as well as antibiotic resistance genes via horizontal gene transfer. The integration of food-borne enterococci into the oral biofilm in-vivo has been observed. Therefore, we investigated the virulence determinants and antibiotic resistance of 97 E. faecalis isolates from the oral cavity, food, and clinical specimens. In addition, phenotypic expression of gelatinase and cytolysin were tested, in-vitro biofilm formation was quantified and isolates were compared for strain relatedness via pulsed field gel electrophoresis (PFGE). Each isolate was found to possess two or more virulence genes, most frequently gelE, efaA, and asa1. Notably, plaque/saliva isolates possessed the highest abundance of virulence genes, the highest levels of phenotypic gelatinase and hemolysin activity and concurrently a high ability to form biofilm. The presence of asa1 was associated with biofilm formation. The biofilm formation capacity of clinical and plaque/saliva isolates was considerably higher than that of food isolates and they also showed similar antibiotic resistance patterns. These results indicate that the oral cavity can constitute a reservoir for virulent E. faecalis strains possessing antibiotic resistance traits and at the same time distinct biofilm formation capabilities facilitating exchange of genetic material.

Enterococcus faecalis attenuates osteogenesis through activation of p38 and ERK1/2 pathways in MC3T3-E1 cells

AIM

To explore the role of Enterococcus faecalis in the proliferation, apoptosis and differentiation of osteoblasts.

METHODOLOGY

Pre-osteoblastic MC3T3-E1 cells were treated with heat-killed E. faecalis ATCC 29212 and clinical E. faecalis P25RC strains, respectively. Cell proliferation, mineralized calcium deposition, alkaline phosphatase (ALP) activity and apoptosis were assessed at various time-points. The expression levels of osteogenic-related genes including ALP, osteocalcin (OC), runt-related protein 2 (Runx2) and collagen type 1 (COL1) were also analysed throughout the duration of the experiment. Additionally, the involvement of mitogen-activated protein kinases (MAPKs) signalling pathways was analysed by Western blotting. In the presence of culture supernatant from E. faecalis-treated murine macrophages, apoptosis of MC3T3-E1 cells was detected with flow cytometry. Data were analysed using analysis of variance (anova), and P < 0.05 was considered significantly different.

RESULTS

E. faecalis significantly inhibited proliferation (P < 0.05) and also significantly induced apoptosis of MC3T3-E1 cells (P < 0.05), whilst differentiation seemed to be unaffected after 7 days of E. faecalis treatment. However, osteogenic differentiation was significantly inhibited with 21-day E. faecalis treatment (P < 0.05). The p38 and ERK1/2 phosphorylation pathways associated with mineral deposition and apoptosis were significantly activated in MC3T3-E1 cells. The culture supernatants from E. faecalis-treated macrophages induced osteoblast apoptosis.

CONCLUSIONS

E. faecalis exerted an inhibitory effect on osteogenesis in pre-osteoblastic MC3T3-E1 cells via phosphorylation of p38 and ERK1/2.

Transcriptome analysis of Enterococcus faecalis in response to alkaline stress

Enterococcus faecalis is the most commonly isolated species from endodontic failure root canals; its persistence in treated root canals has been attributed to its ability to resist high pH stress. The goal of this study was to characterize the E. faecalis transcriptome and to identify candidate genes for response and resistance to alkaline stress using Illumina HiSeq 2000 sequencing. We found that E. faecalis could survive and form biofilms in a pH 10 environment and that alkaline stress had a great impact on the transcription of many genes in the E. faecalis genome. The transcriptome sequencing results revealed that 613 genes were differentially expressed (DEGs) for E. faecalis grown in pH 10 medium; 211 genes were found to be differentially up-regulated and 402 genes differentially down-regulated. Many of the down-regulated genes found are involved in cell energy production and metabolism and carbohydrate and amino acid metabolism, and the up-regulated genes are mostly related to nucleotide transport and metabolism. The results presented here reveal that cultivation of E. faecalis in alkaline stress has a profound impact on its transcriptome. The observed regulation of genes and pathways revealed that E. faecalis reduced its carbohydrate and amino acid metabolism and increased nucleotide synthesis to adapt and grow in alkaline stress. A number of the regulated genes may be useful candidates for the development of new therapeutic approaches for the treatment of E. faecalis infections.

Avaliação da suscetibilidade antimicrobiana de bactérias anaeróbias facultativas isoladas de canais radiculares de dentes com insucesso endodôntico frente aos antibióticos de uso sistêmico

<title>Resumo</title><sec><title>Introdução</title><p>Bactérias associadas ao insucesso do tratamento endodôntico são capazes de adquirir e expressar resistência aos agentes antimicrobianos comumente empregados para tratar infecções, o que torna necessário, em determinadas situações, a realização de testes laboratoriais para detectar a resistência ou a suscetibilidade antimicrobiana desses micro-organismos.</p></sec><sec><title>Objetivo</title><p>avaliar a suscetibilidade antimicrobiana das cepas de <italic>Enterococcus faecalis</italic>, <italic>Enterococcus faecium</italic>, <italic>Actinomyces viscosus</italic> e <italic>Staphylococcus aureus</italic> isoladas de canais radiculares de dentes com insucesso endodôntico.</p></sec><sec><title>Material e método</title><p>Cepas clínicas de <italic>Enterococcus faecalis</italic> (n=3), <italic>Enterococcus faecium</italic> (n=3), <italic>Actinomyces viscosus</italic> (n=3) e <italic>Staphylococcus aureus</italic> (n=3), coletadas in vivo de canais radiculares com insucesso endodôntico, foram testadas quanto à suscetibilidade antimicrobiana por meio do método E-test em duplicata, utilizando os antibióticos: Amoxicilina (AC), Rifampicina (RI), Moxifloxacina (MX), Vancomicina (VA), Tetraciclina (TC), Ciprofloxacina (CI), Cloranfenicol (CL), Benzilpenicilina (PG), Amoxicilina + ácido clavulânico (XL), Doxiciclina (DC), Eritromicina (EM) e Azitromicina (AZ).</p></sec><sec><title>Resultado</title><p>Todas as cepas clínicas testadas foram suscetíveis aos antibióticos AC, XL, PG, DC, MX, TC e VA. Todos os isolados das espécies de <italic>S. aureus</italic> foram suscetíveis aos 12 antibióticos testados. As cepas de <italic>E. faecalis</italic>, <italic>E. faecium</italic> e <italic>A. viscosus</italic> mostraram padrão de suscetibilidade intermediário contra EM. Algumas cepas de <italic>E. faecalis</italic> e <italic>E. faecium</italic> foram resistentes a AZ e RI.</p></sec><sec><title>Conclusão</title><p>As cepas clínicas isoladas dos canais radiculares de dentes com insucesso endodôntico mostraram perfis diferentes de suscetibilidade antimicrobiana e nenhum isolado de <italic>E. faecalis</italic> e <italic>E. faecium</italic>apresentou-se suscetível a AZ e EM.</p></sec>

Propionibacterium acnes Recovered from Atherosclerotic Human Carotid Arteries Undergoes Biofilm Dispersion and Releases Lipolytic and Proteolytic Enzymes in Response to Norepinephrine Challenge In Vitro

In the present study, human atherosclerotic carotid arteries were examined following endarterectomy for the presence of the Gram-positive bacterium Propionibacterium acnes and its potential association with biofilm structures within the arterial wall. The P. acnes 16S rRNA gene was detectable in 4 of 15 carotid artery samples, and viable P. acnes was one among 10 different bacterial species recoverable in culture. Fluorescence in situ hybridization analysis of 5 additional atherosclerotic carotid arteries demonstrated biofilm bacteria within all samples, with P. acnes detectable in 4 samples. We also demonstrated that laboratory-grown cultures of P. acnes biofilms were susceptible to induction of a biofilm dispersion response when challenged with physiologically relevant levels of norepinephrine in the presence of iron-bound transferrin or with free iron. The production and release of lipolytic and proteolytic extracellular enzymes by P. acnes were shown to increase in iron-induced dispersed biofilms, and these dispersion-induced P. acnes VP1 biofilms showed increased expression of mRNAs for the triacylglycerol lipases PPA2105 and PPA1796 and the hyaluronate lyase PPA380 compared to that in untreated biofilms. These results demonstrate that P. acnes can infect the carotid arteries of humans with atherosclerosis as a component of multispecies biofilms and that dispersion is inducible for this organism, at least in vitro, with physiologically relevant levels of norepinephrine resulting in the production and release of degradative enzymes.

A novel termini analysis theory using HTS data alone for the identification of Enterococcus phage EF4-like genome termini

Background

Enterococcus faecalis and Enterococcus faecium are typical enterococcal bacterial pathogens. Antibiotic resistance means that the identification of novel E. faecalis and E. faecium phages against antibiotic-resistant Enterococcus have an important impact on public health. In this study, the E. faecalis phage IME-EF4, E. faecium phage IME-EFm1, and both their hosts were antibiotic resistant. To characterize the genome termini of these two phages, a termini analysis theory was developed to provide a wealth of terminal sequence information directly, using only high-throughput sequencing (HTS) read frequency statistics.

Results

The complete genome sequences of phages IME-EF4 and IME-EFm1 were determined, and our termini analysis theory was used to determine the genome termini of these two phages. Results showed 9 bp 3′ protruding cohesive ends in both IME-EF4 and IME-EFm1 genomes by analyzing frequencies of HTS reads. For the positive strands of their genomes, the 9 nt 3′ protruding cohesive ends are 5′-TCATCACCG-3′ (IME-EF4) and 5′-GGGTCAGCG-3′ (IME-EFm1). Further experiments confirmed these results. These experiments included mega-primer polymerase chain reaction sequencing, terminal run-off sequencing, and adaptor ligation followed by run-off sequencing.

Conclusion

Using this termini analysis theory, the termini of two newly isolated antibiotic-resistant Enterococcus phages, IME-EF4 and IME-EFm1, were identified as the byproduct of HTS. Molecular biology experiments confirmed the identification. Because it does not require time-consuming wet lab termini analysis experiments, the termini analysis theory is a fast and easy means of identifying phage DNA genome termini using HTS read frequency statistics alone. It may aid understanding of phage DNA packaging.

Enterococcus faecalis lipoteichoic acid suppresses Aggregatibacter actinomycetemcomitans lipopolysaccharide-induced IL-8 expression in human periodontal ligament cells

Periodontitis is caused by multi-bacterial infection and Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are closely associated with inflammatory periodontal diseases. Although lipopolysaccharide (LPS) of A. actinomycetemcomitans (Aa.LPS) and lipoteichoic acid of E. faecalis (Ef.LTA) are considered to be major virulence factors evoking inflammatory responses, their combinatorial effect on the induction of chemokines has not been investigated. In this study, we investigated the interaction between Aa.LPS and Ef.LTA on IL-8 expression in human periodontal ligament (PDL) cells. Aa.LPS, but not Ef.LTA, substantially induced IL-8 expression at the protein and mRNA levels. Interestingly, Ef.LTA suppressed Aa.LPS-induced IL-8 expression without affecting the binding of Aa.LPS to Toll-like receptor (TLR) 4. Ef.LTA reduced Aa.LPS-induced phosphorylation of mitogen-activated protein kinases, including ERK, JNK and p38 kinase. Furthermore, Ef.LTA inhibited the Aa.LPS-induced transcriptional activities of the activating protein 1, CCAAT/enhancer-binding protein and nuclear factor-kappa B transcription factors, all of which are known to regulate IL-8 gene expression. Ef.LTA augmented the expression of IL-1 receptor-associated kinase-M (IRAK-M), a negative regulator of TLR intracellular signaling pathways, in the presence of Aa.LPS at both the mRNA and protein levels. Small interfering RNA silencing IRAK-M reversed the attenuation of Aa.LPS-induced IL-8 expression by Ef.LTA. Collectively, these results suggest that Ef.LTA down-regulates Aa.LPS-induced IL-8 expression in human PDL cells through up-regulation of the negative regulator IRAK-M.

An in vivo comparison of internal bacterial colonization in two dental implant systems: identification of a pathogenic reservoir

OBJECTIVES

The aim of this study was to compare internal bacterial colonization in two implant systems, one screw root form (SRF) with an external hexagon connection and one plateau root form (PRF) with a Morse taper internal connection.

MATERIALS AND METHODS

Thirty-two implants; 12 SRF and 20 PRF, were sampled in 15 patients. All implants had been in function for at least 6 months prior to sampling. The implant restoration was removed and 10 µl of sterile saline was introduced into the implant well via a sterile glass syringe. The saline was drawn back up and transferred to the laboratory for microbiological analysis. The number of aerobic and anaerobic colony forming units per millilitre was determined and the dominant micro-organism in each sample was identified by 16s rRNA gene amplicon sequencing.

RESULTS

There was a significant difference between bleeding on probing around the SRF implants (3%) and the PRF implants (28%) (p = 0.0496). Bacterial colonization was identified at 11 SRF and 19 PRF implants. The numbers of anaerobic bacteria recovered from PRF implants was significantly higher than that from SRF implants (p = 0.0002). Streptococcus species and Enterococcus faecalis were found to dominate.

CONCLUSIONS

This in vivo study demonstrated bacterial colonization in both types of implant systems, irrespective of the type of connection. Significantly greater anaerobic counts were found in the Morse taper internal connection implants.

Single consumption of Bryndza cheese temporarily affects oral microbiota and salivary markers of oxidative stress

Several oral diseases are associated with changes in oral microbiota and higher oxidative stress. Enterococcus faecalis has been hypothesized to directly contribute to the oxidative stress in oral cavity. The aim of this study was to examine the effect of single consumption of unpasteurized Bryndza cheese containing enterococci on changes of microbiota and oxidative status in saliva. Fourteen healthy volunteers aged 23-30 years were asked to eat 100 g of Bryndza cheese. Saliva samples were collected before and 1, 10, 100 min, and 24 h after Bryndza cheese consumption. Species-specific PCR and terminal restriction fragment length polymorphism (T-RFLP) analysis were used to characterize oral microbiota. Markers of oxidative stress and antioxidant status were measured in saliva. PCR identified E. faecium in 36 % of probands saliva up to 1 day after consumption of enterococci containing Bryndza cheese. E. faecalis was detected in 57 % of probands saliva up to 10 min and in one proband up to 100 min after Bryndza cheese consumption. T-RFLP analysis confirmed short-term changes in composition of oral microbiota after Bryndza cheese ingestion. Nevertheless, the microbiota was completely restored after 24 h. One minute after ingestion of Bryndza cheese, salivary advanced oxidation protein products were significantly increased (by 74.6 %, P < 0.001), and total antioxidant capacity was decreased (by 22.0 %, P < 0.05). This study shows that single consumption of enterococci containing Bryndza cheese can temporally affect the composition of oral microbiota and oxidative stress in saliva. Further studies should identify the impact of these changes to the pathogenesis of oral diseases.

Bactericidal effect of hydroxyl radicals generated from a low concentration hydrogen peroxide with ultrasound in endodontic treatment

One approach to enhance the disinfection of root canals in endodontic treatment is ultrasonic irrigation with sodium hypochlorite. Reactive oxygen species, such as hydroxyl radical, are generated by biological defense systems to kill invading bacteria. Ultrasonic irrigation with hydrogen peroxide may be a promising option to increase hydroxyl radical generation. We examined the bactericidal effects of hydroxyl radical generated from low concentration hydrogen peroxide with ultrasound in vitro. An ultrasonic tip was submerged in 0.5 or 1.0 M hydrogen peroxide in a microfuge tube. hydrogen peroxide was irradiated with the ultrasound, the tip of which was maintained centered in the tube to mimic ultrasonic irrigation. Hydroxyl radical generation was assessed by electron spin resonance spectroscopy. Subsequently, Enterococcus faecalis suspension in hydrogen peroxide was prepared and irradiated as described above. Bactericidal effects were assessed by viable counting. Electron spin resonance measurements showed that hydroxyl radical generation increased significantly in a time- and dose-dependent manner (two-way analysis of variance and Tukey's test, p<0.05). Moreover, the bactericidal effects of hydrogen peroxide against Enterococcus faecalis were enhanced by ultrasonic irradiation in a time- and dose-dependent manner. These results suggest that ultrasonic irrigation in the presence of low concentration hydrogen peroxide can serve as a disinfection strategy in endodontic treatment.

Investigation of the oral infections and manifestations seen in patients with advanced cancer

Objective: A prospective, observational study was undertaken to investigate the epidemiology of oral infection among the patients with advanced malignancies, and to investigate the effects of therapy strategies and risk factors on the incidence of oral infection.

Methods: The patients with advanced malignancies were enrolled into the study. The incidence of oral infection with different malignant tumor groups or different treatment methods and the diagnoses of oral infection were confirmed. Demographic data on age, gender, bed rest time, nutritional status, smoking habit and the presence of oral prosthesis were also recorded.

Results: Oral infection was prevalent in 46% (391/850) of all cancer patients, with the highest rate in oral and maxillofacial cancer group (67%), followed by Hematological malignancy group (58.6%) and other groups (ranging from 43.3% to 35.3%). Oral candidiasis, oral herpes simplex, and oral mucositis were the popular infectious diseases in the patients. Chemotherapy and radiotherapy, especially combined radio- and chemotherapy, resulted in more oral infections compared with palliative care and surgery. Poor nutritional status and oral prosthesis were identified as independent risk factors associated with oral infection.

Conclusion: Oral infection is prevalent among advanced cancer patients and associated with therapy methods and risk factors. More oral health care should be carried out for the patients with advanced malignant tumor.

Quantitative detection of Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa in human oral epithelial cells from subjects with periodontitis and periodontal health

Epithelial cells in oral cavities can be considered reservoirs for a variety of bacterial species. A polymicrobial intracellular flora associated with periodontal disease has been demonstrated in buccal cells. Important aetiological agents of systemic and nosocomial infections have been detected in the microbiota of subgingival biofilm, especially in individuals with periodontal disease. However, non-oral pathogens internalized in oral epithelial cells and their relationship with periodontal status are poorly understood. The purpose of this study was to detect opportunistic species within buccal and gingival crevice epithelial cells collected from subjects with periodontitis or individuals with good periodontal health, and to associate their prevalence with periodontal clinical status. Quantitative detection of total bacteria and Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis in oral epithelial cells was determined by quantitative real-time PCR using universal and species-specific primer sets. Intracellular bacteria were visualized by confocal microscopy and fluorescence in situ hybridization. Overall, 33% of cell samples from patients with periodontitis contained at least one opportunistic species, compared with 15% of samples from healthy individuals. E. faecalis was the most prevalent species found in oral epithelial cells (detected in 20.6% of patients with periodontitis, P = 0.03 versus healthy individuals) and was detected only in cells from patients with periodontitis. Quantitative real-time PCR showed that high levels of P. aeruginosa and S. aureus were present in both the periodontitis and healthy groups. However, the proportion of these species was significantly higher in epithelial cells of subjects with periodontitis compared with healthy individuals (P = 0.016 for P. aeruginosa and P = 0.047 for S. aureus). Although E. faecalis and P. aeruginosa were detected in 57% and 50% of patients, respectively, with probing depth and clinical attachment level ≥6 mm, no correlation was found with age, sex, bleeding on probing or the presence of supragingival biofilm. The prevalence of these pathogens in epithelial cells is correlated with the state of periodontal disease.

Characterisation of the plasmidome within Enterococcus faecalis isolated from marginal periodontitis patients in Norway

The present study aimed to identify and characterize plasmids in a national collection of oral Enterococcus faecalis (n = 106) isolated from patients with marginal periodontitis. Plasmid replicon typing was performed by multiplex-PCR and sequencing with specific primers for 18 rep-families and 1 unique sequence. Additional plasmid analysis by S1-PFGE was performed for comparison. Totally 120 plasmid replicon amplicons of seven rep-families were identified in 93 E. faecalis strains, e.g. rep9 (prototype pCF10), rep6 (prototype pS86), rep2 (prototype pRE25/pEF1), and rep8 (prototype pAM373). Rep9 was the most predominant rep-family being detected in 81 (76.4%) strains. Forty of these strains were tetracycline resistant and three were erythromycin resistant. Rep6 was the second predominant rep-family being detected in 22 (20.8%) strains. Rep2 was detected in eight (7.5%) strains. All rep2-positive strains were resistant to tetracycline and/or erythromycin and six of them contained Tn916/Tn1545 genes. The rep-positive E. faecalis exhibited divergence in multilocus sequence types (STs). There was a significant correlation between rep9 and ST21, while multiple rep-families appeared in ST40. Totally 145 plasmid bands were identified in 95 E. faecalis strains by S1-PFGE, 59 strains carrying one plasmid, 27 carrying two, five carrying three, three carrying four, and one strain carrying five plasmids. Plasmid sizes varied between 5-150 kbp. There was a significant correlation between the number of plasmids identified by PCR rep-typing and by S1-PFGE. The results indicate that the majority of E. faecalis of marginal periodontitis are likely to be a reservoir for diverse mobile genetic elements and associated antimicrobial resistance determinants.

Low-cost periodontal therapy

Periodontitis is a complex infectious disease that affects low-income individuals disproportionately. Periodontitis is associated with specific bacterial species and herpesviruses, and successful prevention and treatment of the disease is contingent upon effective control of these pathogens. This article presents an efficacious, highly safe, minimally invasive, practical and low-cost periodontal therapy that involves professional and patient-administered mechanical therapy and antimicrobial agents. The major components are scaling for calculus removal, periodontal pocket irrigation with potent antiseptics, and treatment with systemic antibiotics for advanced disease. Povidone-iodine and sodium hypochlorite have all the characteristics for becoming the first-choice antiseptics in the management of periodontal diseases. Both agents show excellent antibacterial and antiviral properties, are readily available throughout the world, have been safely used in periodontal therapy for decades, offer significant benefits for individuals with very limited financial resources, and are well accepted by most dental professionals and patients. Four per cent chlorhexidine applied with a toothbrush to the most posterior part to the tongue dorsum can markedly reduce or eliminate halitosis in most individuals. Systemic antibiotics are used to treat periodontopathic bacteria that are not readily reached by topical therapy, such as pathogens within gingival tissue, within furcation defects, at the base of periodontal pockets, and on the tongue, tonsils and buccal mucosae. Valuable antibiotic therapies are amoxicillin-metronidazole (250 mg of amoxicillin and 250 mg of metronidazole, three times daily for 8 days) for young and middle-aged patients, and ciprofloxacin-metronidazole (500 mg of each, twice daily for 8 days) for elderly patients and for patients in developing countries who frequently harbor enteric rods subgingivally. Scaling to remove dental calculus and the prudent use of inexpensive antimicrobial agents can significantly retard or arrest progressive periodontitis in the great majority of patients.

Antibiotic resistance in human peri-implantitis microbiota

OBJECTIVES

Because antimicrobial therapy is often employed in the treatment of infectious dental implant complications, this study determined the occurrence of in vitro antibiotic resistance among putative peri-implantitis bacterial pathogens.

METHODS

Submucosal biofilm specimens were cultured from 160 dental implants with peri-implantitis in 120 adults, with isolated putative pathogens identified to species level, and tested in vitro for susceptibility to 4 mg/l of doxycycline, 8 mg/l of amoxicillin, 16 mg/l of metronidazole, and 4 mg/l of clindamycin. Findings for amoxicillin and metronidazole were combined post-hoc to identify peri-implantitis species resistant to both antibiotics. Gram-negative enteric rods/pseudomonads were subjected to ciprofloxacin disk diffusion testing.

RESULTS

One or more cultivable submucosal bacterial pathogens, most often Prevotella intermedia/nigrescens or Streptococcus constellatus, were resistant in vitro to clindamycin, amoxicillin, doxycycline, or metronidazole in 46.7%, 39.2%, 25%, and 21.7% of the peri-implantitis subjects, respectively. Only 6.7% subjects revealed submucosal test species resistant in vitro to both amoxicillin and metronidazole, which were either S. constellatus (one subject) or ciprofloxacin-susceptible strains of gram-negative enteric rods/pseudomonads (seven subjects). Overall, 71.7% of the 120 peri-implantitis subjects exhibited submucosal bacterial pathogens resistant in vitro to one or more of the tested antibiotics.

CONCLUSIONS

Peri-implantitis patients frequently yielded submucosal bacterial pathogens resistant in vitro to individual therapeutic concentrations of clindamycin, amoxicillin, doxycycline, or metronidazole, but only rarely to both amoxicillin and metronidazole. Due to the wide variation in observed drug resistance patterns, antibiotic susceptibility testing of cultivable submucosal bacterial pathogens may aid in the selection of antimicrobial therapy for peri-implantitis patients.

Antibiotic susceptibility of periodontal Enterococcus faecalis

BACKGROUND

Enterococcus faecalis may contribute to periodontal breakdown in heavily infected subgingival sites, particularly in patients responding poorly to mechanical forms of periodontal therapy. Because only limited data are available on the antimicrobial sensitivity of enterococci of subgingival origin, this study evaluates the in vitro antibiotic susceptibility of E. faecalis isolated from periodontitis patients in the United States.

METHODS

Pure cultures of 47 subgingival E. faecalis clinical isolates were each inoculated onto specially prepared broth microdilution susceptibility panels containing vancomycin, teicoplanin, and six oral antibiotics of potential use in periodontal therapy. After incubation in ambient air for 18 to 20 hours, minimal inhibitory drug concentrations were determined using applicable Clinical and Laboratory Standards Institute criteria and interpretative guidelines. The organisms were additionally evaluated for in vitro resistance to metronidazole at 4 μg/mL.

RESULTS

Periodontal E. faecalis exhibited substantial in vitro resistance to tetracycline (53.2% resistant), erythromycin (80.8% resistant or intermediate resistant), clindamycin (100% resistant to 2 μg/mL), and metronidazole (100% resistant to 4 μg/mL). In comparison, the clinical isolates were generally sensitive to ciprofloxacin (89.4% susceptible; 10.6% intermediate resistant) and 100% susceptible in vitro to ampicillin, amoxicillin/clavulanate, vancomycin, and teicoplanin.

CONCLUSIONS

Tetracycline, erythromycin, clindamycin, and metronidazole revealed poor in vitro activity against human subgingival E. faecalis clinical isolates, and would likely be ineffective therapeutic agents against these species in periodontal pockets. Among orally administered antibiotics, ampicillin, amoxicillin/clavulanate, and ciprofloxacin exhibited marked in vitro inhibitory activity against periodontal E. faecalis, and may be clinically useful in treatment of periodontal infections involving enterococci.

Virulence factors and antibiotic susceptibility in enterococci isolated from oral mucosal and deep infections

OBJECTIVE

This study evaluates the presence of virulence factors and antibiotic susceptibility among enterococcal isolates from oral mucosal and deep infections.

METHODS

Forty-three enterococcal strains from oral mucosal lesions and 18 from deep infections were isolated from 830 samples that were sent during 2 years to Oral Microbiology, University of Gothenburg, for analysis. The 61 strains were identified by 16S rDNA, and characterized by the presence of the virulence genes efa A (endocarditis gene), gel E (gelatinase gene), ace (collagen binding antigen gene), asa (aggregation substance gene), cyl A (cytolysin activator gene) and esp (surface adhesin gene), tested for the production of bacteriocins and presence of plasmids. MIC determination was performed using the E-test method against the most commonly used antibiotics in dentistry, for example, penicillin V, amoxicillin and clindamycin. Vancomycin was included in order to detect vancomycin-resistant enterococci (VRE) strains.

RESULTS

Sixty strains were identified as Enterococcus faecalis and one as Enterococcus faecium. All the virulence genes were detected in more than 93.3% (efa A and esp) of the E. faecalis strains, while the presence of phenotypic characteristics was much lower (gelatinase 10% and hemolysin 16.7%). Forty-six strains produced bacteriocins and one to six plasmids were detected in half of the isolates.

CONCLUSIONS

Enterococcal strains from oral infections had a high virulence capacity, showed bacteriocin production and had numerous plasmids. They were generally susceptible to ampicillins but were resistant to clindamycin, commonly used in dentistry, and no VRE-strain was found.

In vitro susceptibility of e.faecalis and c.albicans isolates from apical periodontitis to common antimicrobial agents, antibiotics and antifungal medicaments

The aim of this study was to evaluate in vitro antimicrobial activity of 4 antibiotic agents (for E.faecalis) and 4 antifungal agents (for C.albicans) by agar dilution method. Additionally, modified strip diffusion method was used for detection of in vitro antimicrobial activities of 5% NaOCl, 2.5% NaOCl, 17% EDTA and 2% CHX and agar diffusion method for detection of in vitro susceptibilities of three intracanal medicaments for 18 E.faecalis and 18 C.albicans isolates from primary and secondary root canal infection. Isolates were recovered from 231 endodontic samples of patients, with the need of root canal treatment and retreatment. All tested E.faecalis isolates showed resistance to antibiotics. For irrigation solutions, 2% CHX was more effective in eliminating E.faecalis but 5% NaOCl showed larger inhibition zone than 2.5% NaOCl, 17% EDTA and 2% CHX. For intracanal medication, Ca(OH)2-CHX worked efficiently in killing E.faecalis isolates compared to Ca(OH)2-Steril saline solution, Ca(OH)2-Glycerin. For C.albicans, 18 isolates were susceptible to amphotericin B, nistatin, fluconazole but showed resistance to ketoconazole. 5% NaOCl was more effective in eliminating and produced larger inhibition zone compared to 2.5% NaOCl, 17% EDTA and 2% CHX. Ca(OH)2-Glycerin intracanal medication was better in eliminating C.albicans isolates and produced larger inhibition zone compared to other Ca(OH)2 medicaments.

Key words:E.faecalis, C.albicans, antimicrobial, antibiotic, antifungal.

Food-borne enterococci and their resistance to oxidative stress

Enterococci are important food-borne pathogens that cause serious infections. Several virulence factors have been described including aggregation substance, gelatinase, cytolysin, and enterococcal surface protein. The ability to cause infections is mainly dependent on the response to oxidative stress due to the production of reactive oxygen species by immune cells. The aim of our study was to analyze the resistance of enterococcal strains from food to clinically relevant antiseptic agents with regard to the presence of selected virulence factors, and to uncover potential mechanisms of the antioxidative resistance. Eighty-two enterococcal isolates from Bryndza cheese were tested using in vitro growth assays to study the ability of these isolates to survive exposure to antiseptic agents - hydrogen peroxide, hypochlorite, and Chlorhexidine. Virulence genotypes of the isolates were determined by PCR, and RT real time PCR was used for gene expression under oxidative stress. Resistance against antiseptic agents depends on the concentration of applied chemicals, on the time of exposure, but also on virulence factors of the enterococcal strains. Oxidative stress induces the expression of antioxidative enzymes and down-regulates the expression of prooxidative enzymes. These effects are dependent on the virulence genotype of the enterococcal strains. These findings are important for future research, especially concerning the role of enterococci in oral diseases.

The annotated complete DNA sequence of Enterococcus faecalis bacteriophage φEf11 and its comparison with all available phage and predicted prophage genomes

φEf11 is a temperate Siphoviridae bacteriophage isolated by induction from a lysogenic Enterococcus faecalis strain. The φEf11 DNA was completely sequenced and found to be 42,822 bp in length, with a G+C mol% of 34.4%. Genome analysis revealed 65 ORFs, accounting for 92.8% of the DNA content. All except for seven of the ORFs displayed sequence similarities to previously characterized proteins. The genes were arranged in functional modules, organized similar to that of several other phages of low GC Gram-positive bacteria; however, the number and arrangement of lysis-related genes were atypical of these bacteriophages. A 159 bp noncoding region between predicted cI and cro genes is highly similar to the functionally characterized early promoter region of lactococcal temperate phage TP901-1, and possessed a predicted stem-loop structure in between predicted P(L) and P(R) promoters, suggesting a novel mechanism of repression of these two bacteriophages from the λ paradigm. Comparison with all available phage and predicted prophage genomes revealed that the φEf11 genome displays unique features, suggesting that φEf11 may be a novel member of a larger family of temperate prophages that also includes lactococcal phages. Trees based on the blast score ratio grouped this family by tail fiber similarity, suggesting that these trees are useful for identifying phages with similar tail fibers.

Assessment of antimicrobial susceptibility of Enterococcus faecalis isolated from chronic periodontitis in biofilm versus planktonic phase

BACKGROUND

Enterococci are often associated with chronic and recurrent infectious diseases because of their antimicrobial resistance. The aim of this study is to assess antimicrobial susceptibility of Enterococcus faecalis in chronic periodontitis.

METHODS

Antimicrobial susceptibility was determined on 23 E. faecalis strains isolated from patients with chronic periodontitis. Ampicillin, erythromycin, gentamicin, tetracycline, triclosan, and vancomycin were prepared in two-fold serial dilution up to 8,192 μg/mL. Enterococcal biofilm was established by a biofilm device and observed by confocal laser microscopy and scanning electron microscopy. The minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration, and minimum biofilm eradication concentration were determined by spectrophotometer at optical density(650).

RESULTS

A few patches of monolayer early biofilm were observed on the surfaces of biofilm device pegs. The colony-forming units of biofilm per peg were 1.2 × 10(3) to 1.7 × 10(4) and 0 to 20 post-triclosan treatment. The MIC(50) was higher than the MIC epidemiologic cut-off for tetracycline and the MIC(90) was higher than the cut-off for erythromycin and tetracycline, respectively. In biofilm, minimum biofilm eradication concentrations were extremely high for all of the drugs except triclosan.

CONCLUSIONS

The E. faecalis strains of chronic periodontitis exhibited weak biofilm formation ability at the early stage. Over 50% of the strains were resistant to tetracycline, and a few strains were highly resistant to erythromycin or gentamicin. E. faecalis cells in biofilm were hardly eradicated by most of the agents, even in high concentrations. Triclosan was effective in inhibiting E. faecalis growth in both biofilm and planktonic phase.

Prevalence, phenotype, and genotype of Enterococcus faecalis isolated from saliva and root canals in patients with persistent apical periodontitis

INTRODUCTION

The aim of this study was to investigate the prevalence, phenotype, and genotype of Enterococcus faecalis isolated from saliva and root canals in patients with endodontic treatment failure.

METHODS

Samples were collected from 32 adults undergoing retreatment for periapical lesions after endodontic treatment performed at least 2 years previously. Isolates that were presumed to be E. faecalis were identified by both API20 Strep kits and 16S rRNA sequencing. Phenotypic tests for hemolysin and gelatinase production and antibiotic susceptibility were performed. Genotype analysis comprised virulence gene detection and pulsed field gel electrophoresis (PFGE).

RESULTS

The prevalence of E. faecalis was 18.8% in saliva and 40.6% in root canals (P = .666, Fisher exact test). Of the 19 isolates of E. faecalis, 6 were from saliva and 13 were from root canals. In 3 patients, E. faecalis isolates from saliva were more resistant to gentamicin than those from root canals. The genes ace, asa, gelE, cylA, and efaA were detected from all isolates. PFGE after SmaI digestion showed a genetic correlation among all isolates of 62%-100%.

CONCLUSIONS

Phenotype and genotype evidence of potential virulence factors was identified in E. faecalis from both saliva and root canals. A single patient might carry different E. faecalis strains in saliva and root canals.

Occurrence, population structure, and antimicrobial resistance of enterococci in marginal and apical periodontitis

Subgingival plaque samples and root canal samples were collected from 2,839 marginal periodontitis (MP) patients and 21 apical periodontitis (AP) patients. Enterococcus species were identified by a series of phenotypic and genotypic tests. Antimicrobial susceptibility assays were performed by an agar disk diffusion test. Multilocus sequence typing (MLST), eBURST, and minimum spanning tree were used for enterococcal genetic clustering and population analysis. Enterococcus faecalis was recovered from 3.7% MP patients and 9.5% AP patients, and Enterococcus faecium was recovered from 0.04% MP patients. Enterococci were detected more often in older male patients. E. faecalis isolates of MP were found resistant to tetracycline (49.1%), erythromycin (8.5%), trimethoprim (2.8%), and gentamicin (1.9%), while one AP isolate was resistant to tetracycline. A total of 40 sequence types (STs) were resolved in 108 E. faecalis isolates. Comparison with E. faecalis international MLST database revealed that 27 STs were previously found, 13 STs were novel, and several major clonal complexes in the database were also found in MP isolates. The tetracycline-resistant isolates distributed mainly in the major clonal complexes and singletons, whereas the erythromycin-resistant isolates were more dispersed. Although the rate of occurrence of enterococci recovered in the MP and AP samples was low, 50% of these isolates are resistant to at least one antimicrobial agent, which is most often tetracycline. This implies that subgingival E. faecalis might represent a reservoir of resistance to tetracycline and erythromycin. The subgingival E. faecalis isolates show high genetic diversity but are grouped, in general, with the known isolates from the international database.