Enterococcal endocarditis revisited

Novel strategies for vancomycin-resistant Enterococcus faecalis biofilm control: bacteriophage (vB_EfaS_ZC1), propolis, and their combined effects in an ex vivo endodontic model

BACKGROUND

Endodontic treatment failures are predominantly attributed to Enterococcus faecalis (E. faecalis) infection, a Gram-positive coccus. E. faecalis forms biofilms, resist multiple antibiotics, and can withstand endodontic disinfection protocols. Vancomycin-resistant strains, in particular, are challenging to treat and are associated with serious medical complications.

METHODS

A novel phage, vB_EfaS_ZC1, was isolated and characterized. Its lytic activity against E. faecalis was assessed in vitro through time-killing and biofilm assays. The phage's stability under various conditions was determined. Genomic analysis was conducted to characterize the phage and its virulence. The phage, propolis, and their combination were evaluated as an intracanal irrigation solution against a 4-week E. faecalis mature biofilm, using an ex vivo infected human dentin model. The antibiofilm activity was analyzed using a colony-forming unit assay, field emission scanning electron microscopy, and confocal laser scanning microscopy.

RESULTS

The isolated phage, vB_EfaS_ZC1, a siphovirus with prolate capsid, exhibited strong lytic activity against Vancomycin-resistant strains. In vitro assays indicated its effectiveness in inhibiting planktonic growth and disrupting mature biofilms. The phage remained stable under wide range of temperatures (- 80 to 60 °C), tolerated pH levels from 4 to 11; however the phage viability significantly reduced after UV exposure. Genomic analysis strongly suggests the phage's virulence and suitability for therapeutic applications; neither lysogeny markers nor antibiotic resistance markers were identified. Phylogenetic analysis clustered vB_EfaS_ZC1 within the genus Saphexavirus. The phage, both alone and in combination with propolis, demonstrated potent antibiofilm effects compared to conventional root canal irrigation.

CONCLUSION

Phage vB_EfaS_ZC1 demonstrates a promising therapy, either individually or in combination with propolis, for addressing challenging endodontic infections caused by E. faecalis.

Exploring the antimicrobial potential of 4,5,7-trihydroxyflavanone (THF) against vancomycin-resistant Enterococcus gallinarum infections: in vitro and in silico investigations

Enterococcus gallinarum and other Enterococcus species commonly inhabit the human gastrointestinal tract. While the pathogenicity of Enterococcus gallinarum remains incompletely understood, its infections are alarmingly severein humans, as evidenced by numerous cases. Formerly, Vancomycin was the preferred drug, but recent findings indicate that clinical isolates of Enterococcus gallinarum are resistant, leading to the emergence of vancomycin-resistant enterococci (VRE) strains. The escalation of drug resistance is often linked to overexpressed virulence factors, some of which are implicated in biofilm formation in Enterococcus infections. Henceforth, this research investigates the potential of phytocompounds to combat E. gallinarum infection, employing both in vitro and in silico methodologies. In vitro techniques were employed to assess the efficacy of various phytocompounds, ultimately identifying 4,5,7-trihydroxyflavanone (THF) as particularly effective in inhibiting microbial growth. THF displayed over 80% antibacterial activity at 200 µg/ml against E. gallinarum. Subsequent qualitative and quantitative hemolysin assays implicated hemolysin as a target of THF. Molecular docking analysis of THF and Hemolysin A revealed a strong binding affinity. Notably, residues Asn18, Asp85, and His199 formed hydrogen bonds, while His22 and His86 were involved in robust π-π stacking and π-cation interactions with THF. Overall, this study highlights THF's potential in combating E. gallinarum infections.Communicated by Ramaswamy H. Sarma.

C-terminal deletion of RelA protein is suggested as a possible cause of infective endocarditis recurrence with Enterococcus faecium

Infective endocarditis (IE) caused by Enterococcus spp. represents the third most common cause of IE, with high rates of relapse compared with other bacteria. Interestingly, late relapses (>6 months) have only been described in Enterococcus faecalis, but here we describe the first reported IE relapse with Enterococcus faecium more than a year (17 months) after the initial endocarditis episode. Firstly, by multi locus sequence typing (MLST), we demonstrated that both isolates (EF646 and EF641) belong to the same sequence type (ST117). Considering that EF641 was able to overcome starvation and antibiotic treatment conditions surviving for a long period of time, we performed bioinformatic analysis in identifying potential genes involved in virulence and stringent response. Our results showed a 13-nucleotide duplication (positions 1638-1650) in the gene relA, resulting in a premature stop codon, with a loss of 167 amino acids from the C-terminal domains of the RelA enzyme. RelA mediates the stringent response in bacteria, modulating levels of the alarmone guanosine tetraphosphate (ppGpp). The relA mutant (EF641) was associated with lower growth capacity, the presence of small colony variants, and higher capacity to produce biofilms (compared with the strain EF646), but without differences in antimicrobial susceptibility patterns according to standard procedures during planktonic growth. Instead, EF641 demonstrated tolerance to high doses of teicoplanin when growing in a biofilm. We conclude that all these events would be closely related to the long-term survival of the E. faecium and the late relapse of the IE. These data represent the first clinical evidence of mutations in the stringent response (relA gene) related with E. faecium IE relapse.

Factors Related to the Development of Infective Endocarditis in Hemodialysis Patients in a Third-Level Hospital in Panama

INTRODUCTION

Venous access for hemodialysis (HD) makes patients more susceptible to transient bacteremia, predisposing them to the development of infective endocarditis (IE). Among the risk factors observed in this population are temporary access to HD, hypoalbuminemia, diabetes mellitus, female gender, anemia, and colonization by methicillin-resistant Staphylococcus aureus (MRSA).

METHODOLOGY

A retrospective case-control study with a one-to-two ratio was carried out on patients with chronic kidney disease (CKD) undergoing renal replacement therapy with at least one vascular access for HD at Complejo Hospitalario Dr. Arnulfo Arias Madrid (CHDrAAM) from 2010 to 2020. Sociodemographic variables, past medical history, and data on current HD were studied. The odds ratio (OR) and adjusted odds ratio (aOR) were calculated for the collected variables.

RESULTS

No statistically significant differences between the groups were observed in sociodemographic variables. In terms of past medical history, the cases showed a predominance of coronary disease (47.6% vs 4.8%; OR: 37.27), valvular disease (23.8% vs 0%), and heart failure (33.3% vs 4.8%; OR: 10). In the cases, the use of a temporary catheter was more prevalent (61.9% vs 33.3%; OR: 3.25), and subclavian access was more frequently recorded (28.6% vs 2.4%; OR: 14.4). A short duration of venous access (<30 days) was found in a greater proportion of cases (23.8% vs 4.8%; OR: 6.25). The main pathogen isolated was S. aureus (33.3%), and the most affected valve was the aortic valve (59.1%). Fever was found in 100% of the reported cases, and up to 47.6% presented with a recent murmur.

DISCUSSION

Similar to previous studies conducted in other countries, we identified a history of pre-existing valve disease, the use of a temporary catheter, and recent venous access as risk factors. Contrary to what has been reported in the literature, this study did not find female sex, diabetes mellitus, and hypoalbuminemia as risks.

CONCLUSION

Factors such as a history of coronary artery disease, heart failure, preexisting valvular disease, the use of a temporary catheter, subclavian venous access, and short duration of venous access (<30 days) were identified as risk factors for the development of IE in patients with CKD on HD.

Relationship among Streptococcus gallolyticus Subsp. gallolyticus, Enterococcus faecalis and Colorectal Neoplasms in Recurrent Endocarditis: A Historical Case Series

Objectives: The role of colorectal neoplasms (CRN) as a common potential source of recurrent Streptococcus gallolyticus subsp. gallolyticus (SGG) and Enterococcus faecalis (EF) endocarditis remains unstudied. We aimed to investigate what proportion of episodes of recurrent endocarditis are caused by a succession of SGG and EF, or vice versa, and to assess the role of a colonic source in such recurrent episodes. Methods: we conducted a retrospective analysis of two prospective endocarditis cohorts (1979–2019) from two Spanish hospitals, providing descriptive analyses of the major features of the endocarditis episodes, colonoscopy findings, and histologic results. Results: among 1552 IE episodes, 204 (13.1%) were caused by EF and 197 (12.7%) by SGG, respectively. There were 155 episodes (10%) of recurrent IE, 20 of which (12.9%) were due to a succession of SGG/EF IE in 10 patients (the first episode caused by SGG in eight cases, and by EF in two cases). The median follow-up was 86 (interquartile range 34–156) months. In 8/10 initial episodes, the causative microorganism was SGG, and all patients were diagnosed with CRN either during the initial episode or during follow-up. During the second episode of IE or follow-up, colonoscopies revealed CRN in six patients. Conclusions: There seems to be an association between SGG and EF in recurrent endocarditis that warrants further investigation. Our findings reinforce the need for systematically performing colonoscopy in the event of endocarditis caused by both microorganisms.

Ampicillin Plus Ceftriaxone Regimen against Enterococcus faecalis Endocarditis: A Literature Review

Enterococcus faecalis infective endocarditis (EFIE) continues to represent a potentially fatal infectious disease characterized by elevated morbidity and mortality. Despite advances in antimicrobial therapy, changing demographics and the reduced availability of useful antibiotics combined with the dissemination of multi-drug resistant strains, the mortality rate remained unchanged in the last decades. Nowadays, optimizing the antibiotic regimen is still of paramount importance. Historically, aminoglycosides were considered as a cornerstone for treatment even though their use is associated with a high risk of kidney failure. It is against this background that, in recent years, several studies have been carried in order to assess the validity of alternative therapeutic approaches, including combinations of beta-lactams, that, acting synergistically, have yielded useful results in different clinical settings. In this scenario, we searched and critically report clinical studies assessing the efficacy and safety of double beta-lactam therapy in treating EFIE.

Enterococcus faecalis endocarditis: what's next?

Enterococcus faecalis infective endocarditis (EFIE) is a complex entity in rapid evolution. Although largely relevant findings from recent studies have advanced the knowledge on EFIE and led to some changes in clinical guidelines, there are still a number of gaps to be filled. Coordinated, international, multicenter efforts are needed to obtain quality data that rend the health systems and scientific community prepared enough to understand and handle this infection. In this Perspective, some of the most relevant aspects concerning the epidemiology, clinical presentation and outcomes, diagnostic approaches and antibiotic therapy of EFIE are addressed. Also, several potential future clinical developments in the field are discussed.

Infective Endocarditis in Patients on Chronic Hemodialysis

BACKGROUND

Infective endocarditis (IE) is a common and serious complication in patients receiving chronic hemodialysis (HD).

OBJECTIVES

This study sought to investigate whether there are significant differences in complications, cardiac surgery, relapses, and mortality between IE cases in HD and non-HD patients.

METHODS

Prospective cohort study (International Collaboration on Endocarditis databases, encompassing 7,715 IE episodes from 2000 to 2006 and from 2008 to 2012). Descriptive analysis of baseline characteristics, epidemiological and etiological features, complications and outcomes, and their comparison between HD and non-HD patients was performed. Risk factors for major embolic events, cardiac surgery, relapses, and in-hospital and 6-month mortality were investigated in HD-patients using multivariable logistic regression.

RESULTS

A total of 6,691 patients were included and 553 (8.3%) received HD. North America had a higher HD-IE proportion than the other regions. The predominant microorganism was Staphylococcus aureus (47.8%), followed by enterococci (15.4%). Both in-hospital and 6-month mortality were significantly higher in HD versus non-HD-IE patients (30.4% vs. 17% and 39.8% vs. 20.7%, respectively; p < 0.001). Cardiac surgery was less frequently performed among HD patients (30.6% vs. 46.2%; p < 0.001), whereas relapses were higher (9.4% vs. 2.7%; p < 0.001). Risk factors for 6-month mortality included Charlson score (hazard ratio [HR]: 1.26; 95% confidence interval [CI]: 1.11 to 1.44; p = 0.001), CNS emboli and other emboli (HR: 3.11; 95% CI: 1.84 to 5.27; p < 0.001; and HR: 1.73; 95% CI: 1.02 to 2.93; p = 0.04, respectively), persistent bacteremia (HR: 1.79; 95% CI: 1.11 to 2.88; p = 0.02), and acute onset heart failure (HR: 2.37; 95% CI: 1.49 to 3.78; p < 0.001).

CONCLUSIONS

HD-IE is a health care-associated infection chiefly caused by S. aureus, with increasing rates of enterococcal IE. Mortality and relapses are very high and significantly larger than in non-HD-IE patients, whereas cardiac surgery is less frequently performed.

How do I manage a patient with enterococcal bacteraemia?

BACKGROUND

Enterococcal bacteraemia (EB) is common, particularly in the nosocomial setting, and its management poses a challenge for clinicians and microbiologists.

OBJECTIVES

The aim was to summarize the more relevant features of EB and to provide a practical state-of-the-art on the topics that more directly affect its management.

SOURCES

Pubmed articles from inception to 31 May 2020.

CONTENT

The following topics are covered: epidemiological, clinical and microbiological characteristics and factors associated with prognosis of EB; diagnosis and work-up, including the use of echocardiography to rule out endocarditis; antibiotic management with special focus on antimicrobial resistance and complicated EB; and the role of infectious disease consultation and the use of bundles in EB. In addition, three clinical vignettes are presented to illustrate the practical application of the guidance provided, and major gaps in the current evidence supporting EB management are discussed.

IMPLICATIONS

EB is associated with large burdens of morbidity and mortality, particularly among fragile and immunosuppressed patients presenting complicated bacteraemia due to multidrug-resistant enterococci. Most cases of EB are caused by Enterococcus faecalis, followed by E. faecium. EB often presents as polymicrobial bacteraemia. Rapidly identifying patients at risk of EB is crucial for timely application of diagnostic techniques and empiric therapy. Early alert systems and rapid diagnostic techniques, such as matrix-assisted desorption ionization-time of flight mass spectrometry, especially if used together with infectious disease consultation within bundles, appear to improve management and prognosis of EB. Echocardiography is also key in the work-up of EB and should probably be more extensively used, although its exact indications in EB are still debated. Multidisciplinary approaches are warranted due to the complexity and severity of EB.

Four weeks versus six weeks of ampicillin plus ceftriaxone in Enterococcus faecalis native valve endocarditis: A prospective cohort study

Enterococcus faecalis infective endocarditis (EFIE) is a severe disease of increasing incidence. The objective was to analyze whether the outcome of patients with native valve EFIE (NVEFIE) treated with a short course of ampicillin plus ceftriaxone (4wAC) was similar to patients treated according to international guidelines (6wAC). Between January 2008 and June 2018, 1,978 consecutive patients with definite native valve IE were prospectively included in a national registry. Outcomes of patients with NVEFIE treated with 4wAC were compared to those of patients who received 6wAC. Three hundred and twenty-two patients (16.3%) had NVEFIE. One hundred and eighty-three (56.8%) received AC. Thirty-nine patients (21.3%) were treated with 4wAC for four weeks and 70 patients (38.3%) with 6wAC. There were no differences in age or comorbidity. Patients treated 6wAC presented a longer duration of symptoms before diagnosis (21 days, IQR 7-60 days vs. 7 days, IQR 1-22 days; p = 0.002). Six patients presented perivalvular abscess and all of these received 6wAC. Surgery was performed on 14 patients (35.9%) 4wAC and 34 patients (48.6%) 6wAC (p = 0.201). In-hospital mortality, one-year mortality and relapses among 4wAC and 6wAC patients were 10.3% vs. 11.4% (p = 0.851); 17.9% vs. 21.4% (p = 0.682) and 5.1% vs. 4.3% (p = 0.833), respectively. In conclusion, a four-week course of AC may be considered as an alternative regimen in NVEFIE, notably in patients with shorter duration of symptoms and those without perivalvular abscess. These results support the performance of a randomized clinical trial to evaluate the efficacy of this short regimen.

A Contemporary Picture of Enterococcal Endocarditis

BACKGROUND

Enterococcal endocarditis (EE) is a growing entity in Western countries. However, quality data from large studies is lacking.

OBJECTIVES

The purpose of this study was to describe the characteristics and analyze the prognostic factors of EE in the GAMES cohort.

METHODS

This was a post hoc analysis of a prospectively collected cohort of patients from 35 Spanish centers from 2008 to 2016. Characteristics and outcomes of 516 cases of EE were compared with those of 3,308 cases of nonenterococcal endocarditis (NEE). Logistic regression and Cox proportional hazards regression analysis were performed to investigate risk factors for in-hospital and 1-year mortality, as well as relapses.

RESULTS

Patients with EE were significantly older; more frequently presented chronic lung disease, chronic heart failure, prior endocarditis, and degenerative valve disease; and had higher median age-adjusted Charlson score. EE more frequently involved the aortic valve and prosthesis (64.3% vs. 46.7%; p < 0.001; and 35.9% vs. 28.9%; p = 0.002, respectively) but less frequently pacemakers/defibrillators (1.5% vs. 10.5%; p < 0.001), and showed higher rates of acute heart failure (45% vs. 38.3%; p = 0.005). Cardiac surgery was less frequently performed in EE (40.7% vs. 45.9%; p = 0.024). No differences in in-hospital and 1-year mortality were found, whereas relapses were significantly higher in EE (3.5% vs. 1.7%; p = 0.035). Increasing Charlson score, LogEuroSCORE, acute heart failure, septic shock, and paravalvular complications were risk factors for mortality, whereas prior endocarditis was protective and persistent bacteremia constituted the sole risk factor for relapse.

CONCLUSIONS

Besides other baseline and clinical differences, EE more frequently affects prosthetic valves and less frequently pacemakers/defibrillators. EE presents higher rates of relapse than NEE.

Infective Endocarditis Following Transcatheter Aortic Valve Replacement: Comparison of Balloon- Versus Self-Expandable Valves

BACKGROUND

No data exist about the characteristics of infective endocarditis (IE) post-transcatheter aortic valve replacement (TAVR) according to transcatheter valve type. We aimed to determine the incidence, clinical characteristics, and outcomes of patients with IE post-TAVR treated with balloon-expandable valve (BEV) versus self-expanding valve (SEV) systems.

METHODS

Data from the multicenter Infectious Endocarditis After TAVR International Registry was used to compare IE patients with BEV versus SEV.

RESULTS

A total of 245 patients with IE post-TAVR were included (SEV, 47%; BEV, 53%). The timing between TAVR and IE was similar between groups (SEV, 5.5 [1.2-15] months versus BEV, 5.3 [1.7-11.4] months; P=0.89). Enterococcal IE was more frequent in the SEV group (36.5% versus 15.4%; P<0.01), and vegetation location differed according to valve type (stent frame, SEV, 18.6%; BEV, 6.9%; P=0.01; valve leaflet, SEV, 23.9%; BEV, 38.5%; P=0.01). BEV recipients had a higher rate of stroke/systemic embolism (20.0% versus 8.7%, adjusted OR: 2.46, 95% CI: 1.04-5.82, P=0.04). Surgical explant of the transcatheter valve (SEV, 8.7%; BEV, 13.8%; P=0.21), and in-hospital death at the time of IE episode (SEV, 35.6%; BEV, 37.7%; P=0.74) were similar between groups. After a mean follow-up of 13±12 months, 59.1% and 54.6% of the SEV and BEV recipients, respectively, had died (P=0.66).

CONCLUSIONS

The characteristics of IE post-TAVR, including microorganism type, vegetation location, and embolic complications but not early or late mortality, differed according to valve type. These results may help to guide the diagnosis and management of IE and inform future research studies in the field.

Non-HACEK Gram-negative bacillus endocarditis

PATIENTS AND METHODS

Retrospective analysis of clinical data using 26 diagnosed non-HACEK Gram-negative infective endocarditis cases from nine hospitals in Turkey.

RESULTS

Mean age of patients was 53 (28-84) years, with a 23% case fatality. Nineteen (73%) of the 26 patients had at least one predisposing factor. The presence of a central venous catheter was the most common predisposing factor (7/26 patients). Pseudomonasaeruginosa (7/26 patients) and Escherichiacoli (7/26 patients) were the most common pathogens. The median duration of the antibiotic therapy was 42 days (range 3-84 days). Surgical procedures were performed in 10 patients. The case fatality was similar in patients who did or did not undergo surgery (20% vs. 25%).

In Silico and Experimental Data Claiming Safety Aspects and Beneficial Attributes of the Bacteriocinogenic Strain Enterococcus faecalis B3A-B3B

This study aimed at comparing the genome of Enterococcus faecalis B3A-B3B, a bacteriocinogenic strain recently isolated from a healthy Iraqi infant to those of Enterococci of clinical and beneficial grades. The putative genes gelE, cpd, efaAfm, ccf, agg, and cob coding for virulence factors were detected in B3A-B3B strain, which meanwhile resulted to be non-cytotoxic, non-hemolytic, devoid of inflammatory effects, and sensitive to most of the antibiotics tested except for clindamycin and trimethoprim, which resistance is usually ascribed to intrinsic nature. B3A-B3B strain was remarkable for its hydrophobicity, auto-aggregation, adhesion to human Caco-2 cells, and survival in simulated gastrointestinal conditions, and cholesterol assimilation fulfilling therefore key beneficial attributes.

A rationale for combination ampicillin and daptomycin in renal transplant patients with enterococcal infective endocarditis

Treatment of enterococcal endocarditis in patients with history of renal transplantation is complicated. Treatment failure and/or drug toxicities are not uncommon. Treatment with ampicillin and daptomycin in a renal transplant patient has been rarely reported. Here we report a patient who was successfully treated with this novel combination.

Early in vitro development of daptomycin non-susceptibility in high-level aminoglycoside-resistant Enterococcus faecalis predicts the efficacy of the combination of high-dose daptomycin plus ampicillin in an in vivo model of experimental endocarditis

Background

Previous studies showed development of daptomycin non-susceptibility (DNS: MIC >4 mg/L) in Enterococcus faecalis infections. However, no studies have assessed the efficacy of the combination of daptomycin/ampicillin against E. faecalis strains developing DNS in the experimental endocarditis (EE) model.

Objectives

To assess the in vitro and in vivo efficacy of daptomycin at 10 mg/kg/day, daptomycin/ampicillin and ampicillin/ceftriaxone against two high-level aminoglycoside-resistant E. faecalis strains, one developing DNS after in vitro exposure to daptomycin and another that did not (DS).

Methods

Subculture of 82 E. faecalis strains from patients with endocarditis with daptomycin MICs, time-kill and in vivo experiments using the EE model.

Results

33% of the strains (27 of 82) displayed DNS after subculture with daptomycin. Daptomycin MIC rose from 0.5-2 to 8-16 mg/L. In time-kill experiments, when using a high inoculum (10 8 cfu/mL), daptomycin/ampicillin was synergistic for one-third of DS strains and none of DNS strains, while ampicillin/ceftriaxone retained synergy in all cases. In the EE model, daptomycin did not significantly reduce cfu/g from vegetations compared with control against either strain, while daptomycin/ampicillin reduced significantly more cfu/g than daptomycin against the DS strain, but not against the DNS strain [2.9 (2.0-4.1) versus 6.1 (4.5-8.0); P  =   0.002]. Ampicillin/ceftriaxone was synergistic and bactericidal against both strains, displaying the same activity as daptomycin/ampicillin against the DS strain.

Conclusions

Performance of an Etest for daptomycin MIC after subculture with daptomycin inhibitory doses on strains of high-level aminoglycoside-resistant E. faecalis endocarditis may be an easy test to predict the in vivo efficacy of daptomycin/ampicillin.

The Changing Epidemiology of Infective Endocarditis in the Twenty-First Century

PURPOSE OF THE REVIEW

Infective endocarditis (IE) is a relatively infrequent infectious disease. It does, however, causes serious morbidity, and its mortality rate has remained unchanged at approximately 25%. Changes in IE risk factors have deeply impacted its epidemiology during recent decades but literature from low-income countries is very scarce. Moreover, prophylaxis guidelines have recently changed and the impact on IE incidence is still unknown.

RECENT FINDINGS

In high-income countries, the proportion of IE related to prior rheumatic disease has decreased significantly and has been replaced proportionally by cases related to degenerative valvulopathies, prosthetic valves, and cardiovascular implantable electronic devices. Nosocomial and non-nosocomial-acquired cases have risen, as has the proportion caused by staphylococci, and the median age of patients. In low-income countries, in contrast, rheumatic disease remains the main risk factor, and streptococci the most frequent causative agents. Studies performed to evaluate impact of guidelines changes' have shown contradictory results. The increased complexity of cases in high-income countries has led to the creation of IE teams, involving several specialties. New imaging and microbiological techniques may increase sensitivity for diagnosis and detection of IE cases. In low-income countries, IE remained related to classic risk factors. The consequences of prophylaxis guidelines changes are still undetermined.

Porphyromonas gingivalis is the most abundant species detected in coronary and femoral arteries

An association between oral bacteria and atherosclerosis has been postulated. A limited number of studies have used 16S RNA gene sequencing-based metagenomics approaches to identify bacteria at the species level from atherosclerotic plaques in arterial walls. The objective of this study was to establish detailed oral microbiome profiles, at both genus and species level, of clinically healthy coronary and femoral artery tissues from patients with atherosclerosis. Tissue specimens were taken from clinically non-atherosclerotic areas of coronary or femoral arteries used for attachment of bypass grafts in 42 patients with atherosclerotic cardiovascular disease. Bacterial DNA was sequenced using the MiSeq platform, and sequence reads were screened in silico for nearly 600 oral species using the HOMINGS ProbeSeq species identification program. The number of sequence reads matched to species or genera were used for statistical analyses. A total of 230 and 118 species were detected in coronary and femoral arteries, respectively. Unidentified species detected by genus-specific probes consisted of 45 and 30 genera in coronary and in femoral artery tissues, respectively. Overall, 245 species belonging to 95 genera were detected in coronary and femoral arteries combined. The most abundant species were Porphyromonas gingivalis, Enterococcus faecalis, and Finegoldia magna based on species probes. Porphyromonas, Escherichia, Staphylococcus, Pseudomonas, and Streptococcus genera represented 88.5% mean relative abundance based on combined species and genus probe detections. Porphyromonas was significantly more abundant than Escherichia (i.e. 46.8% vs. 19.3%; p = 0.0005). This study provides insight into the presence and types of oral microbiome bacterial species found in clinically non-atherosclerotic arteries.

Phage therapy against Enterococcus faecalis in dental root canals

Antibiotic resistance is an ever-growing problem faced by all major sectors of health care, including dentistry. Recurrent infections related to multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, and vancomycin-resistant enterococci (VRE) in hospitals are untreatable and question the effectiveness of notable drugs. Two major reasons for these recurrent infections are acquired antibiotic resistance genes and biofilm formation. None of the traditionally known effective techniques have been able to efficiently resolve these issues. Hence, development of a highly effective antibacterial practice has become inevitable. One example of a hard-to-eradicate pathogen in dentistry is Enterococcus faecalis, which is one of the most common threats observed in recurrent root canal treatment failures, of which the most problematic to treat are its biofilm-forming VRE strains. An effective response against such infections could be the use of bacteriophages (phages). Phage therapy was found to be highly effective against biofilm and multidrug-resistant bacteria and has other advantages like ease of isolation and possibilities for genetic manipulations. The potential of phage therapy in dentistry, in particular against E. faecalis biofilms in root canals, is almost unexplored. Here we review the efforts to develop phage therapy against biofilms. We also focus on the phages isolated against E. faecalis and discuss the possibility of using phages against E. faecalis biofilm in root canals.

Infective endocarditis

Infective endocarditis (IE) is a rare, life-threatening disease that has long-lasting effects even among patients who survive and are cured. IE disproportionately affects those with underlying structural heart disease and is increasingly associated with health care contact, particularly in patients who have intravascular prosthetic material. In the setting of bacteraemia with a pathogenic organism, an infected vegetation may form as the end result of complex interactions between invading microorganisms and the host immune system. Once established, IE can involve almost any organ system in the body. The diagnosis of IE may be difficult to establish and a strategy that combines clinical, microbiological and echocardiography results has been codified in the modified Duke criteria. In cases of blood culture-negative IE, the diagnosis may be especially challenging, and novel microbiological and imaging techniques have been developed to establish its presence. Once diagnosed, IE is best managed by a multidisciplinary team with expertise in infectious diseases, cardiology and cardiac surgery. Antibiotic prophylaxis for the prevention of IE remains controversial. Efforts to develop a vaccine that targets common bacterial causes of IE are ongoing, but have not yet yielded a commercially available product.

Enterococcal Infective Endocarditis following Periodontal Disease in Dogs

In humans, one of the major factors associated with infective endocarditis (IE) is the concurrent presence of periodontal disease (PD). However, in veterinary medicine, the relevance of PD in the evolution of dogs’ endocarditis remains poorly understood. In order to try to establish a correlation between mouth-associated Enterococcus spp. and infective endocarditis in dogs, the present study evaluated the presence and diversity of enterococci in the gum and heart of dogs with PD. Samples were collected during necropsy of 32 dogs with PD and visually diagnosed with IE, which died of natural causes or euthanasia. Enterococci were isolated, identified and further characterized by Pulsed-Field Gel Electrophoresis (PFGE); susceptibility to antimicrobial agents and pathogenicity potential was also evaluated. In seven sampled animals, PFGE-patterns, resistance and virulence profiles were found to be identical between mouth and heart enterococci obtained from the same dog, allowing the establishment of an association between enterococcal periodontal disease and endocarditis in dogs. These findings represent a crucial step towards understanding the pathogenesis of PD-driven IE, and constitute a major progress in veterinary medicine.