Infective endocarditis by HACEK: a review

Aggregatibacter actinomycetemcomitans: From the Oral Cavity to the Heart Valves

Aggregatibacter actinomycetemcomitans (A. actinomycetecomitans) is a Gram-negative bacterial species that is an essential component of the oral microbiota. Due to its aggregative properties, it plays a role in the pathogenesis of human diseases. The presence of the surface proteins Fim, Briae, and microvesicles enables the bacterium to adhere to the epithelial surface and the tooth's surface. The presence of leukotoxin A (LtxA), which plays an important role in the pathogenicity of the bacterium, has been associated with both periodontitis and the etiology of rheumatoid arthritis (RA). A. actinomycetecomitans is also associated with several other systemic diseases and complications, such as endocarditis and different abscesses. In addition to leukotoxin A, A. actinomycetecomitans possesses several different virulence factors, including bacteriocins, chemotaxis inhibitory factors, cytotoxic factors, Fc-binding proteins, immunosuppressive factors, lipopolysaccharide collagenase, fibroblast inhibitory factors, antibiotic resistance determinants, adhesins, invasive factors and factors that inhibit the function of polymorphonuclear leukocytes. The ability of A. actinomycetemcomitans lipopolysaccharide to induce macrophages to secrete the interleukins IL-1, IL-1β, and tumor necrosis factor (TNF) is of considerable importance. The primary etiologic factor in the pathogenesis of periodontal disease is the oral biofilm colonized by anaerobic bacteria. Among these, A. actinomycetemcomitans occupies an important place as a facultative anaerobic bacterium. In addition, A. actinomycetemcomitans possesses many virulence factors that contribute to its potential to cause cancer. This article provides an overview of the virulence factors of A. actinomycetecomitans and its association with various systemic diseases, its oncogenic potential, and the treatment options for infections caused by A. actinomycetecomitans.

Periodontal pathogens and cancer development

Increasing evidence suggests a significant association between periodontal disease and the occurrence of various cancers. The carcinogenic potential of several periodontal pathogens has been substantiated in vitro and in vivo. This review provides a comprehensive overview of the diverse mechanisms employed by different periodontal pathogens in the development of cancer. These mechanisms induce chronic inflammation, inhibit the host's immune system, activate cell invasion and proliferation, possess anti-apoptotic activity, and produce carcinogenic substances. Elucidating these mechanisms might provide new insights for developing novel approaches for tumor prevention, therapeutic purposes, and survival improvement.

A Case Report of Acute Infective Endocarditis Caused by Aggregatibacter aphrophilus Involving the Tricuspid Valve

We report a case of a 16-year-old male with tricuspid valve infective endocarditis caused by Aggregatibacter aphrophilus and complicated by pulmonary septic embolisms. Multiple antimicrobial therapy was unsuccessful and surgical management was required. In this report, the authors highlight the importance of a high index of suspicion regarding the diagnosis of endocarditis and its possible complications.

Bacteria of healthy periodontal tissues as candidates of probiotics: a systematic review

OBJECTIVES

The use of probiotics could promote the balance of the subgingival microbiota to contribute to periodontal health. This study aimed to identify the potential of bacteria commonly associated with healthy periodontal tissues as probiotic candidates.

MATERIAL AND METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the PubMed, Scopus, Science Direct, ProQuest, and Ovid databases as well as the combination of Medical Subject Headings (MeSH) and non-MeSH terms. Based on the selection criteria, original studies published in English and identifying the microorganisms present in the periodontium of healthy individuals and patients with periodontitis using the high-throughput 16S ribosomal gene sequencing technique were included.

RESULTS

Out of 659 articles, 12 met the criteria for this review. These articles were published from 2012 to 2020 and mainly originated from the United States, China, and Spain. Most of these studies reported adequate criteria for selecting participants, using standardized clinical criteria, and compliance with quality based on the tools used. In periodontal healthy tissue were identified species like Actinomyces viscosus, Actinomyces naeslundii, Haemophilus parainfluenzae, Rothia dentocariosa, Streptococcus sanguinis, Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus intermedius, and Prevotella nigrescens which have recognized strains with a capacity to inhibit periodontopathogens.

CONCLUSIONS

S. sanguinis, S. oralis, S. mitis, and S. gordonii are among the bacterial species proposed as potential probiotics because some strains can inhibit periodontopathogens and have been reported as safe for humans.

Aggregatibacter actinomycetemcomitans endocarditis in an adult patient with patent ductus arteriosus

Introduction

Aggregatibacter (Actinobacillus) actinomycetemcomitans is a commensal bacterial pathogen in the human oral cavity. It can, however, represent the source of local or systemic infections with serious evolution, in particular infective endocarditis. We present a particular case of an adult male patient with infective endocarditis with A. actinomycetemcomitans and patent ductus arteriosus (PDA).

Case report

A 37-year-old patient, chronic ethanol user, is hospitalized for altered general condition, persistent cough, left chest pain, headache and dizziness, symptoms evolving for about 3 weeks. The clinical examination revealed crackling pulmonary rales present basally bilaterally, as well as numerous cavities and dental abscesses. Chest radiography showed mixed left hiliobasal pneumonia. Chest CT depicted pulmonary abscess and two filling defects in the pulmonary artery trunk, possible thrombotic/vegetative images/mediastinal thrombotic/adenopathic images. Broad spectrum antibiotic treatment was initiated. Transthoracic ultrasonography visualized persistence of ductus arteriosus and an echodense formation attached to the lateral wall of the pulmonary artery trunk. Following positive blood cultures for Aggregatibacter actinomycetemcomitans, the diagnosis of infective endocarditis was established and antibiotic treatment was de-escalated to ceftriaxone according to the antibiogram. The clinical course under treatment was slowly favorable, the patient was discharged on request on day 44 with continued treatment at home.

Conclusions

Infective endocarditis caused by Aggregatibacter actinomycetemcomitans should be considered in patients with altered general condition and congenital cardiovascular defects. In the present case, the patient presented two risk factors, namely poor dental hygiene and PDA.

Haemophilus parainfluenza-Associated Aortic Root Abscess and Septic Embolic Stroke Post-transcatheter Aortic Valve Replacement: A Case Study

We present a rare instance of aortic root abscess and septic embolic stroke due to Haemophilus parainfluenza in a 75-year-old male patient who had undergone a recent transcatheter aortic valve replacement. The patient initially presented with generalized weakness and altered mental status. Blood cultures grew Haemophilus parainfluenza. Brain imaging showed multiple infarcts with some areas of hemorrhagic conversion. Echocardiography demonstrated an aortic root abscess as well as vegetation on the tricuspid valve. Surgical correction was deemed high risk; hence, management involved intravenous (IV) antibiotics, resulting in the resolution of both symptoms and the abscess.

Haemophilus parainfluenzae infective endocarditis complicated by multiorgan septic emboli

Infective endocarditis (IE) caused by Haemophilus parainfluenzae is a rare but serious condition if not diagnosed and treated promptly. In this article, we describe a patient with H. parainfluenzae IE who initially presented with non-specific symptoms but subsequently developed multiple sequelae of IE. The diagnosis of IE was made based on clinical, echocardiographic, radiological and microbiological findings. He was treated successfully with a mitral valve replacement along with 4 weeks of intravenous antibiotic therapy. Our case highlights the importance of obtaining a thorough history and a complete physical examination to ensure an early diagnosis of IE.

Impact of Periodontitis on the Leakage of Oral Bacteria to the Gut

Colorectal cancer (CRC) and periodontitis have recently been related due to the higher incidence of CRC in periodontal patients and the involvement of periodontal pathogens in carcinogenesis, suggesting that leakage from the oral cavity to the gut occurs. However, the magnitude of this pass-through in healthy individuals is controversial, and the effect that periodontitis could play in it is understudied. To evaluate the rate of bacterial leakage from the oral cavity to the gut, we analyzed the microbial composition of saliva, subgingival plaque, and fecal samples in healthy individuals without gastrointestinal disorders, including 20 periodontitis patients and 20 oral healthy controls, using PacBio full-length 16S rRNA gene sequencing. As expected, we observed a higher abundance of periodontal pathogens in the subgingival plaque and saliva of periodontal patients. In contrast, no significant differences were found between the fecal samples of both groups, implying that gut samples from periodontal patients were not enriched in periodontal pathogens. Fusobacterium nucleatum, a biomarker of CRC, was not found in the fecal samples of any participant. Our study does show a small leakage of some oral bacteria (mainly streptococci) to the gut, regardless of periodontal health status. Future studies should test whether other host factors and/or the preexistence of a gut disorder must be present in addition to periodontitis to promote the colonization of the gut by oral pathogens. The absence of periodontal pathogens in feces supports the idea that these bacteria could be used as biomarkers of intestinal disorders, including CRC.

A Case of Gemella morbillorum Causing Multi-valvular Endocarditis

This is the case of a 31-year-old man with no significant past medical history who presented to the emergency department experiencing persistent fevers, chills, and malaise for the past 2-3 weeks. During this period, he had multiple urgent care visits for possible left-sided otitis media which was treated with short a course of Augmentin. While on antibiotics his symptoms would improve, but they would reappear once he had finished treatment. The patient also had significant dental carries with a chronic right molar infection. At the emergency department, blood cultures grew two out of two Gemella morbillorum. Transthoracic echocardiography showed a 1 cm x 0.5 cm mobile density on the left coronary cusp of the aortic valve with moderate-severe aortic insufficiency. The patient was started on empiric IV vancomycin. Further workup revealed that the source of infection was dental carries. While proceeding with a transesophageal echocardiogram, the patient went into flash pulmonary edema requiring ICU admission. Imaging revealed an elongated 1.7 cm x 0.6 cm vegetation attached to the base of the left coronary cusp on the left ventricular outflow tract side with severe aortic regurgitation and a small 0.8 cm x 0.8 cm vegetation on the atrial side of the anterior mitral leaflet at A2 associated with mitral leaflet perforation with severe mitral regurgitation. Oral surgery removed the infected teeth. Cardiothoracic surgery performed open heart valve replacement which revealed a completely destroyed aortic valve, droplet vegetation, and destruction of the mitral valve leading to mechanical valve replacement. The patient received a two-week course of gentamycin while in the ICU with meropenem. Once sensitivities were back, he was switched to IV penicillin therapy for a total of six weeks.

The Bacterial Oral Microbiome in Children with Congenital Heart Disease: An Extensive Review

Children with congenital heart disease have poorer oral health compared with healthy children. Oral diseases, such as dental caries and gingivitis, are associated with the oral microbiome. The objective of this review was to find evidence of differences in the bacterial colonization of the oral cavity of children with congenital heart disease (CHD) versus healthy children. A literature review was conducted according to predetermined criteria, including the need for controlled clinical trials. Half of the 14 studies that met the inclusion criteria reported significant differences in bacterial colonization in children with congenital heart disease. A variety of influencing factors were discussed. There is some evidence for alterations in the oral microflora as a result of physiopathological and treatment-related factors in children with CHD, but additional research is required to validate these findings.

Oral microbiota study of the patients after hospitalisation for COVID-19, considering selected dental indices and antibiotic therapy using the next generation sequencing method (NGS)

Background

Poor oral hygiene and the increased incidence and severity of periodontitis may exacerbate SARS-CoV-2 infection. The aim was to evaluate the oral microbiota of 60 participants divided into groups: COVID-19 convalescents who received antibiotics during hospitalization (I), COVID-19 convalescents without antibiotic therapy (II) and healthy individuals (III).

Materials and Methods

Dental examination was conducted, and oral health status was evaluated using selected dental indexes. Clinical samples (saliva, dorsal swabs, supragingival and subgingival plaque) were collected and used for metagenomic library to the next-generation sequencing (NGS) preparation.

Results

Each of the clinical materials in particular groups of patients showed a statistically significant and quantitatively different bacterial composition. Patients from group I showed significantly worse oral health, reflected by higher average values of dental indexes and also a higher percentage of Veillonella, Tannerella, Capnocytophaga and Selenomonas genera in comparison to other groups. Additionally, a statistically significant decrease in the amount of Akkermansia type in both groups with COVID-19 was observed for all materials.

Conclusions

The primary factor affecting the composition of oral microbiota was not the SARS-CoV-2 infection itself, but the use of antibiotic therapy. The increased percentage of pro-inflammatory pathogens observed in COVID-19 patients underscores the importance of preventing periodontal disease and improving oral hygiene in the future.

Prophylactic antibiotic use for infective endocarditis: a systematic review and meta-analysis

OBJECTIVES

Infective endocarditis (IE) is a devastating disease with a 50% 1-year mortality rate. In recent years, medical authorities across the globe advised stricter criteria for antibiotic prophylaxis in patients with high risk of IE undergoing dental procedures. Whether such recommendations may increase the risk of IE in at-risk patients must be investigated.

DESIGN

Prospectively registered systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, Scopus and ClinicalTrials.gov were searched through 23 May 2022, together with an updated search on 5 August 2023.

ELIGIBILITY CRITERIA

All primary studies reporting IE within 3 months of dental procedures in adults >18 years of age were included, while conference abstracts, reviews, case reports and case series involving fewer than 10 cases were excluded.

DATA EXTRACTION AND SYNTHESIS

All studies were assessed by two reviewers independently, and any discrepancies were further resolved through a third researcher.

RESULTS

Of the 3771 articles screened, 38 observational studies fit the inclusion criteria and were included in the study for subsequent analysis. Overall, 11% (95% CI 0.08 to 0.16, I2=100%) of IE are associated with recent dental procedures. Streptococcus viridans accounted for 69% (95% CI 0.46 to 0.85) of IE in patients who had undergone recent dental procedures, compared with only 21% (95% CI 0.17 to 0.26) in controls (p=0.003). None of the high-risk patients developed IE across all studies where 100% of the patients were treated with prophylactic antibiotics, and IE patients are 12% more likely to have undergone recent dental manipulation compared with matched controls (95% CI 1.00 to 1.26, p=0.048).

CONCLUSIONS

Although there is a lack of randomised control trials due to logistic difficulties in the literature on this topic, antibiotic prophylaxis are likely of benefit in reducing the incidence of IE in high-risk patients after dental procedures. Further well-designed high-quality case-control studies are required.

TRIAL REGISTRATION NUMBER

CRD42022326664.

Challenges and Insights in Aggregatibacter aphrophilus endocarditis: a review of literature

Infective endocarditis is a serious disease associated with high mortality despite recent advances in diagnosis and treatment. Aggregatibacter aphrophilus is a fastidious Gram-negative member of the HACEK organisms (Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). A. aphrophilus is associated with dental infections but has also been implicated in cases of infective endocarditis. We highlight the importance of a high index of suspicion in symptomatic patients with an initial negative blood culture, particularly in high-risk groups such as patients with congenital valve disease and prosthetic valve. The knowledge of this rare entity may lead to early diagnosis and appropriate management. We review the main characteristics of Aggregatibacter aphrophilus endocarditis reported in the medical literature.

An insidious Aggregatibacter actinomycetemcomitans infection of an ascending aortic endovascular graft

While HACEK group organisms cause only 1-3% of infective endocarditis (IE) cases, their insidious and varied clinical presentations make for difficult and often delayed diagnoses. We present a 65-year-old male with persistent exertional dyspnea, hemoptysis, and weight loss who was diagnosed with a HACEK aortic graft infection and IE.

An Unexpected Outcome of Streptococcus sanguinis Endocarditis Associated With Orthodontic Bracing in a Young Healthy Patient

We present a case of Streptococcus sanguinis endocarditis in a 26-year-old female following orthodontic bracing. The rarity and debilitating consequences of endocarditis caused by Streptococcus sanguinis are elaborated. The patient exhibited severe regurgitation with the eccentric posteriorly directed flow, leading to significant cardiac strain, further accentuated by systolic flow reversal in the right superior pulmonary vein. Surgical intervention, including mitral valve replacement, was crucial in addressing the underlying infection, restoring valve function, and preventing further complications. However, a second mitral valve replacement was performed due to recurrent bioprosthesis endocarditis. This case underscores the unique challenges of Streptococcus sanguinis endocarditis, emphasizing the need for a multidisciplinary approach and individualized decision-making to optimize patient care.

Transesophageal Echocardiography vs. Transthoracic Echocardiography for Methicillin-Sensitive Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Endocarditis

Infective endocarditis is an infection of the inner layers of the heart, seen often in intravenous drug users and patients with valvular lesions or prosthetic heart valves. This entity has high mortality and morbidity. The most common causative microorganism is Staphylococcus aureus. In this comprehensive literature review, we focused on both Staphylococcus aureus infections, i.e., methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) endocarditis, demographics, use of transthoracic echocardiogram and/or transesophageal echocardiogram for diagnostics, and treatments. Although clinical criteria are relevant, transesophageal echocardiogram plays a vital role in establishing and identifying the presence of infective endocarditis and its local complications, with higher sensitivity in patients with prosthetic valves. The antibiotic selection posed a great challenge for clinicians due to antibiotic resistance and the aggressive nature of Staphylococcus aureus. Early diagnosis of infective endocarditis, when suspected, and effective management by a multispecialty team can improve the outcome for the patients.

Ceftriaxone-induced neutropenia successfully overcome by a switch to penicillin G in Cardiobacterium hominis endocarditis

Leukopenia, including agranulocytosis, is a severe complication of treatment with all β-lactam antibiotics. Its incidence increases with age. Cardiobacterium hominis endocarditis after implantation of an aortic valve bio-prosthesis in a 77-year-old woman was treated with ceftriaxone 2 g/day plus gentamicin 160 mg/day intravenously. On Day 25 of treatment, blood leukocytes had decreased to 1800/μl (neutrophils 370/μl). Antibiotic therapy was switched to penicillin G 20 million international units (IU)/day. Thereafter, blood leukocytes including neutrophils normalized suggesting that penicillin G was less bone marrow-toxic than ceftriaxone. High-dose ciprofloxacin, the alternative to penicillin G, was avoided because of the risk of cognitive and behavioral side effects. The present case suggests that with close laboratory monitoring a β-lactam with differing side chains should not be considered contraindicated after β-lactam antibiotic-induced neutropenia.

In Vitro Selection of Lactobacillus and Bifidobacterium Probiotic Strains for the Management of Oral Pathobiont Infections Associated to Systemic Diseases

The human oral pathobionts Aggregatibacter actinomycetemcomitans, Streptococcus mitis and Streptococcus mutans, in dysbiosis-promoting conditions, lead to oral infections, which also represent a threat to human systemic health. This scenario may be worsened by antibiotic misuse, which favours multi-drug resistance, making the research on pathogen containment strategies more than crucial. Therefore, we aimed to in vitro select the most promising probiotic strains against oral pathogen growth, viability, biofilm formation, and co-aggregation capacity, employing both the viable probiotics and their cell-free supernatants (CFSs). Interestingly, we also assessed probiotic efficacy against the three-pathogen co-culture, mimicking an environment similar to that in vivo. Overall, the results showed that Lactobacillus CFSs performed better than the Bifidobacterium, highlighting Limosilactobacillus reuteri LRE11, Lacticaseibacillus rhamnosus LR04, Lacticaseibacillus casei LC04, and Limosilactobacillus fermentum LF26 as the most effective strains, opening the chance to deeper investigation of their action and CFS composition. Altogether, the methodologies presented in this study can be used for probiotic efficacy screenings, in order to better focus the research on a viable probiotic, or on its postbiotics, suitable in case of infections.