Current Issues in the Diagnosis and Management of Blood Culture-Negative Infective and Non-Infective Endocarditis

Aortic Valve Endocarditis in an Intravenous Drug User With Psychiatric History: A Diagnostic Challenge

Infective endocarditis (IE), a life-threatening cardiac infection, can present atypically, complicating diagnosis. We present a case of a 45-year-old male patient with schizophrenia and intravenous drug use (IVDU) who presented with suicidal ideation. Though afebrile, he exhibited tachycardia, bilateral pedal edema, bronchial breath sounds, and a diastolic murmur. Echocardiography identified an extensive aortic valve vegetation and a reduced ejection fraction. Despite negative resected valve cultures and Gram staining, emergency aortic valve replacement and left atrial appendage clipping were performed, followed by a six-week antibiotic course. This case underscores the diagnostic challenge of afebrile, culture-negative IE, likely due to prior antibiotics or fastidious organisms, particularly in high-risk populations like those with IVDU. Psychiatric presentations may obscure typical IE symptoms, necessitating heightened clinical suspicion and comprehensive evaluation, including echocardiography, even without classic signs like fever or leukocytosis. Timely intervention and individualized diagnostics are critical to improving outcomes in such complex cases.

Pathogenic spectrum of infective endocarditis and analysis of prognostic risk factors following surgical treatment in a tertiary hospital in China

BACKGROUND

This study aimed to summarize the pathogenic spectrum of infective endocarditis (IE) and analyze the risk factors for poor prognosis in surgical patients in a tertiary hospital in China.

METHODS

We retrospectively included patients diagnosed with IE between January 2013 and January 2022. The pathogenic spectrum was summarized; the risk factors for early postoperative mortality and embolic events were analyzed using multivariate logistic regression.

RESULTS

Among 630 patients who underwent blood cultures, the positivity rate was 56.83%. The most prevalent pathogens were viridans streptococci, Staphylococcus aureus, enterococci, and coagulase-negative staphylococci (CoNS). The prevalence of viridans streptococci significantly increased in the surgically treated group, compared to the medically treated group (50.80% vs. 27.78%, P < 0.001), while that of CoNS decreased (5.60% vs. 12.04%, P = 0.034). There has been a declining trend in the blood culture positivity in recent years compared to earlier years (2018-2022 vs. 2013-2017 = 60.95% vs. 47.30%, P = 0.037), with an increasing trend in viridans streptococci and a decreasing trend in CoNS. Multivariate logistic regression analysis identified male gender, coronary artery disease, platelet count < 100 × 109/L, albumin < 35 g/L, elevated creatinine, and prosthetic valve as independent risk factors for early postoperative mortality. Risk factors for embolic events included recent cerebral infarction within 3 months, history of peripheral vasculopathy, and hemoglobin (Hb) < 90 g/L.

CONCLUSIONS

Viridans streptococci predominates as the most common IE pathogen, with its incidence rising recently, especially among surgical patients. Blood culture positivity is decreasing. Understanding risk factors for early postoperative mortality and embolic events is crucial for optimizing patient management and prognosis.

CLINICAL TRIAL NUMBER

Not applicable.

Culture-Negative Endocarditis Complicated by Cerebral Abscesses Due to Streptococcus gordonii: A Diagnostic Odyssey

Endocarditis is a serious diagnostic entity that carries a high rate of morbidity and mortality, with complications including heart failure, septic embolization, brain abscesses, and stroke. Blood culture-negative endocarditis (BCNE) represents a particularly challenging clinical scenario where the causative organism is undetectable, either due to being difficult to culture or due to the empiric administration of antimicrobial agents. This entity generally results in delayed diagnosis and treatment of endocarditis, with a potential increase in the rate of complications. In this report, we present a case of multiple brain abscesses resulting from BCNE, where the causative organism - and hence effective treatment - was only identified with the implementation of modern molecular diagnostic techniques like Karius, isothermal amplification methods, etc. We also highlight the specific entities of BCNE, its pathogenesis, and differential diagnosis, as well as the effective diagnostic and therapeutic options available to date.

Diagnostic Benefit of Molecular Imaging in Patients Undergoing Heart Valve Surgery for Infective Endocarditis

(1) Background: The successful treatment of infective endocarditis (IE) relies on detecting causative pathogens to administer targeted antibiotic therapy. In addition to standard microbiological cultivation of pathogens from tissue obtained during heart valve surgery, the potential of molecular biological methods was evaluated. (2) Methods: A retrospective study was performed on heart valve tissue from 207 patients who underwent heart valve surgery for IE. FISHseq (fluorescence in situ hybridization combined with 16S rRNA gene PCR and sequencing) was performed in addition to conventional culture-based microbiological diagnostics. The diagnostic performance of FISHseq was compared with the conventional methods and evaluated in the clinical context. (3) Results: Overall, FISHseq provided a significantly higher rate of specific pathogen detection than conventional valve culture (68.1% vs. 33.3%, p < 0.001). By complementing the findings from blood culture and valve culture, FISHseq was able to provide a new microbiological diagnosis in 10% of cases, confirm the cultural findings in 24.2% of cases and provide greater diagnostic accuracy in 27.5% of cases. FISHseq could identify a pathogen in blood-culture-negative IE in 46.2% of cases, while valve culture provided only 13.5% positive results (p < 0.001). (4) Conclusions: This study demonstrates that using FISHseq as an additional molecular biological technique for diagnostics in IE adds substantial diagnostic value, with potential implications for the treatment of IE. It provides pathogen detection, especially in cases where conventional microbiological cultivation is negative or inconclusive.

Libman-Sacks Endocarditis in a Congenital Valve Defect: A Case Report

Libman-Sacks endocarditis (LSE) is a rare complication of systemic lupus erythematosus (SLE), characterized by noninfectious vegetation on normal heart valves. We present the case of a 20-year-old woman with SLE and a congenital valve malformation. Despite a year of effective SLE treatment, she later developed stage IV dyspnea, chest pain, and signs of right heart failure. Investigations revealed active lupus, mitral valve vegetation, agenesis of the posterior mitral leaflet, and severe mitral insufficiency. The patient was treated with corticosteroids, antibiotics, anticoagulants, and symptomatic heart failure management. Despite initial improvement, her condition deteriorated, and she did not respond to resuscitation. While LSE often responds well to treatment, severe valvulopathy, particularly with congenital valve defects, can result in fatal outcomes.

Diagnostic Work-Up in Patients with Nonbacterial Thrombotic Endocarditis

Nonbacterial thrombotic endocarditis (NBTE) is a form of endocarditis that occurs in patients with predisposing conditions, including malignancies, autoimmune diseases (particularly antiphospholipid antibody syndrome, which accounts for the majority of lupus-associated cases), and coagulation disturbances for which the correlation with classical determinants is unclear. The condition is commonly referred to as "marantic", "verrucous", or Libman-Sacks endocarditis, although these are not synonymous, representing clinical-pathological nuances. The clinical presentation of NBTE involves embolic events, while local valvular complications, generally regurgitation, are typically less frequent and milder compared to infective forms of endocarditis. In the past, the diagnosis of NBTE relied on post mortem examinations, while at present, the diagnosis is primarily based on echocardiography, with the priority of excluding infective endocarditis through comprehensive microbiological and serological tests. As in other forms of endocarditis, besides pathology, transesophageal echocardiography remains the diagnostic standard, while other imaging techniques hold promise as adjunctive tools for early diagnosis and differentiation from infective vegetations. These include cardiac MRI and 18FDG-PET/CT, which already represents a major diagnostic criterion of infective endocarditis in specific settings. We will herein provide a comprehensive review of the current knowledge on the clinics and therapeutics of NBTE, with a specific focus on the diagnostic tools.

Blood culture-negative infective endocarditis presenting with atypical dermatologic manifestation: A rare case report and review of the literature

Infective endocarditis (IE) rarely presents with cutaneous manifestations due to earlier diagnosis and treatment. We present a case of middle-aged male patient presenting with an erythematous papular rash in the upper extremities and left knee, further progressing into painful ulcers with crusted and necrotic center in the arms and fingers. These cutaneous lesions were further followed by shaking chills and fever, which brought the patient to our hospital. Laboratory evaluation revealed elevated ESR (erythrocyte sedimentation rate) and C-reactive protein. Blood cultures taken were negative. Biopsy of the skin lesions were consistent with cutaneous leukocytoclastic vasculitis, and the gram smear revealed gram-positive cocci. The patient developed dyspnea and chest pain, which raised suspicion for IE. TEE (transesophageal echocardiography) demonstrated mild LV diastolic dysfunction, 1+ tricuspid valve regurgitation, mild mitral regurgitation, and vegetation-like lesions on the surface of mitral valve leaflets, consequently IE was confirmed. In conclusion, clinicians must look carefully for skin manifestations in cases with high likelihood of IE, even when other typical symptoms are absent.

A retrospective analysis of blood culture-negative endocarditis at a tertiary care centre in Switzerland

AIMS OF THE STUDY

Numerous studies from different countries have contributed to an improved understanding of blood culture-negative infective endocarditis. However, little is known about its epidemiology and microbiology in Switzerland. We aimed to assess the epidemiology and microbiology of blood culture-negative endocarditis at the University Hospital Zurich, Switzerland.

METHODS

We screened all patients hospitalised between 1997 and 2020 with possible or definite endocarditis at our institution. Thereof, we identified all cases with blood culture-negative endocarditis and retrospectively retrieved patient characteristics, microbiological, histopathological, radiographic and surgical data from medical records.

RESULTS

Among 861 patients screened, 66 (7.7%) cases of blood culture-negative endocarditis were identified. Thereof, 31 cases could be microbiologically documented or not documented (n = 30), and in five cases a non-infectious aetiology was confirmed. Endocarditis predominantly affected men (77%) and the left heart (79%); predisposing factors were prosthetic valves (42%), congenital heart disease (35%) and prior endocarditis (14%). The most common reasons for negative blood cultures were antibiotic treatment prior to blood culture sampling (35%), fastidious and slow growing microorganisms (30%) and definite non-infective endocarditis (8%). Coxiella burnetii and Bartonella spp. were the most common fastidious bacteria identified. In addition to serology, identification of causative microorganisms was possible by microbiological and/or histopathological analysis of tissue samples, of which polymerase chain reaction testing (PCR) of the 16S ribosomal RNA proved to be most successful.

CONCLUSIONS

The present study provides a detailed analysis of blood culture-negative endocarditis over a time span of more than 20 years in Zurich, Switzerland. Antibiotic treatment prior to blood collection, and fastidious and slow growing organisms were identified as main reasons for sterile blood cultures. Typical culture-negative bacteria were mainly found by PCR and/or culture of tissue samples.

Immune mechanisms associated with cardiovascular disease in systemic lupus erythematosus: A path to potential biomarkers

Systemic lupus erythematosus (SLE) patients display an increased risk of cardiovascular disease (CVD). With the improved clinical management of other classical severe manifestation of the disease, CVD is becoming one of the most relevant complications of SLE, and it is an important factor causing morbidity and mortality. Several immune constituents have been shown to be involved in the pathogenesis of atherosclerosis and endothelial damage in SLE patients, including specific circulating cell populations, autoantibodies, and inflammatory mediators. In this review, we summarize the presentation of CVD in SLE and the role of the autoimmune responses present in SLE patients in the induction of atherogenesis, endothelial impairment and cardiac disease. Additionally, we discuss the utility of these immune mediators as early CVD biomarkers and targets for clinical intervention in SLE patients.

A Review of Cardiac Manifestations in Patients With Systemic Lupus Erythematosus and Antiphospholipid Syndrome With Focus on Endocarditis

Patients with autoimmune diseases such as systemic lupus erythematosus (SLE) or antiphospholipid syndrome (APS) are at a higher risk for adverse cardiovascular events associated with increased morbidity and mortality. The increased risk of these events is often associated with rheumatic heart disease (heart valve or mural endocardium damage from rheumatic fever) following microbial infection (i.e., untreated or under-treated streptococcal infection). In particular, the weakening of cardiac vasculature due to rheumatic heart disease makes such patients with autoimmune diseases more susceptible to endocarditis. Endocarditis can be caused by an infection (infective endocarditis) or inflammation tied to disease activity (non-bacterial thrombotic endocarditis [NBTE]). Infective endocarditis among patients with autoimmune diseases may result from exposure to pathogens during dental or surgical procedures. NBTE commonly occurs as a result of fibrin and platelet aggregation on the cardiac valves without bacterial infection. While diagnosis and management can vary based on underlying etiology, an interdisciplinary approach that includes prevention and management from dentists, cardiologists, rheumatologists, and primary care physicians is needed. In addition, increasing patient and physician education on risk factors and prevention strategies is much needed. This manuscript will review the pathophysiology of endocarditis, the association between SLE and APS and endocarditis risk, the diagnosis and management of these autoimmune diseases with a focus on the prevention of cardiovascular disease risk, and make recommendations for diagnostic and management approaches to improve care. 

A case of endocarditis and spondylodiscitis associated with Mycobacterium tuberculosis

Tuberculosis (TB) is a global health problem, in which the majority of cases occur in population-dense developing countries. Despite advances in various diagnostic TB modalities, extrapulmonary TB remains a challenge due to complexities related to its diagnostic approach. Hereby, we present a rare case of endocarditis and spondylodiscitis associated with Mycobacterium tuberculosis (MTB). This case report highlighted the challenges faced in diagnosing blood culture-negative infective endocarditis (BCNIE). We also emphasized the importance of considering MTB as etiology of BCNIE, particularly in endemic TB areas.

Coronary artery embolism and culture-negative endocarditis post Bentall's procedure

Infective endocarditis is an important cause of morbidity and mortality, which classically presents with fevers and nonspecific symptoms. Afebrile infective endocarditis with negative blood cultures makes diagnosis more challenging and delays in treatment can occur increasing the likelihood of complications. The presence of prosthetic heart valves places patients at an increased risk of infective endocarditis and the case described below highlights the importance of considering this diagnosis even if classic clinical features such as fever and raised inflammatory markers are not present, as well as discussing an unusual complication of infective endocarditis; coronary artery embolism leading to myocardial infarction.

Blood culture-negative infective endocarditis: a worse outcome? Results from a large multicentre retrospective Spanish cohort study

BACKGROUND

To assess the impact of blood cultures negative infective endocarditis (BCNIE) on in-hospital mortality.

METHODS

Prospective multicentre study with retrospective analysis of a Spanish cohort including adult patients with definite IE. Cardiac implantable devices infection were excluded. Comparisons between blood cultures positive and BCNIE groups were performed to analyse in-hospital mortality.

RESULTS

1001 cases were included of which 83 (8.3%) had BCNIE. Alternative microbiological diagnosis was achieved for 39 (47%) out 83 cases. The most frequent identifications were: Coxiella burnetii (11; 28.2%), Tropheryma whipplei (4; 10.3%), Streptococcus gallolyticus (4;10.3%) and Staphylococcus epidermidis (3; 7.7%). Surgery was performed more frequently in BCNIE group (57.8 vs. 36.9%, p < .001). All-cause in-hospital mortality rate was 26.7% without statistical difference between compared groups. BCNIE was not associated to worse mortality rate in Cox regression model (aHR = 1.37, 95% CI 0.90-2.07, p = .14). Absence of microbiological diagnosis was also not associated to worse in-hospital prognosis (aHR = 1.62, 95% CI 0.99-2.64, p = .06).

CONCLUSIONS

In our cohort, BCNIE was not associated to greater in-hospital mortality based in multivariate Cox regression models. The variables most frequently associated with mortality were indicated but not performed surgery (aHR = 2.48, 95% CI 1.73-3.56, p < .001), septic shock (aHR = 2.24, 95% CI 1.68-2.99, p < .001), age over 65 years (aHR = 1.88, 95% CI 1.40-2.52, p < .001) and complicated endocarditis (aHR = 1.79, 95% CI 1.36-2.37, p < .001).

Diagnostic stewardship based on patient profiles: differential approaches in acute versus chronic infectious syndromes

Introduction: New diagnostics may be useful in clinical practice, especially in contexts of high prevalence of multidrug-resistant organisms (MDRO). However, misuse of diagnostic tools may lead to increased costs and worse patient outcome. Conventional and new techniques should be appropriately positioned in diagnostic algorithms to guide an appropriate use of antimicrobial therapy.Areas covered: A panel of experts identified 4 main areas in which the implementation of diagnostic stewardship is needed. Among chronic infections, bone and prosthetic joint infections and subacute-chronic intravascular infections and endocarditis represent common challenges for clinicians. Among acute infections, bloodstream infections and community-acquired pneumonia may be associated with high mortality and require appropriate diagnostic approach.Expert opinion: Diagnostic stewardship aims to improve the appropriate use of microbiological diagnostics to guide therapeutic decisions through appropriate and timely diagnostic testing. Here, diagnostic algorithms based on different patient profiles are proposed for chronic and acute clinical syndromes. In each clinical scenario, combining conventional and new diagnostic techniques is crucial to make a rapid and accurate diagnosis and to guide the selection of antimicrobial therapy. Barriers related to the implementation of new rapid diagnostic tools, such as high initial costs, may be overcome through their rational and structured use.

Current Challenges in the Management of Infective Endocarditis

Infective endocarditis is a relatively rare, but deadly cause of sepsis, with an overall mortality ranging from 20 to 25% in most series. Although the classic clinical classification into syndromes of acute or subacute endocarditis have not completely lost their usefulness, current clinical forms have changed according to the profound epidemiological changes observed in developed countries. In this review, we aim to address the changing epidemiology of endocarditis, several recent advances in the understanding of the pathophysiology of endocarditis and endocarditis-triggered sepsis, new useful diagnostic tools as well as current concepts in the medical and surgical management of this disease. Given its complexity, the management of infective endocarditis requires the close collaboration of multidisciplinary endocarditis teams that must decide on the diagnostic approach; the appropriate initial treatment in the critical phase; the detection of patients needing surgery and the timing of this intervention; and finally the accurate selection of patients for out-of-hospital treatment, either at home hospitalization or with oral antibiotic treatment.

Culture-negative endocarditis with neurologic presentations and dramatic response to heparin: a case report

Background

Blood culture-negative endocarditis (BCNE) is diagnosed in 2–7% of patients with infective endocarditis (IE) and recent antibiotic use is a known risk factor. Altered mental status may be a presenting symptom. Besides empiric antibiotics, intravenous anticoagulation using heparin may have a role in the management of such patients.

Case presentation

A 23-year-old male patient was referred to our center with fever, altered mental status and abnormal gait. Neurologic examination revealed Wernicke’s aphasia. Cardiac auscultation revealed systolic murmur at the left sternal border. ECG (electrocardiogram) was unremarkable. Brain MRI showed multiple cerebellar lesions. Transthoracic echocardiography (TTE) demonstrated three large masses on the right ventricle (RV), tricuspid valve (TV), and anterior mitral valve (MV) leaflet. Blood cultures (three sets) were negative. Intravenous heparin therapy was administered. After 48 h, the second TTE demonstrated that one valvular lesion disappeared and the other two lesions showed a significant decrease in size. The patient’s neurological symptoms resolved gradually. Further workup for collagen vascular disorders did not show any abnormality.

Conclusion

BCNE should be considered in patients with fever and neurologic manifestations. TTE should be performed to detect valvular abnormalities. Intravenous heparin could be used in such patients when TTE demonstrate valvular vegetations.

Infective endocarditis at a tertiary-care hospital in China

Background

The aim of this study was to describe the clinical features and outcome of infective endocarditis at a general hospital in China and to identify the risk factors associated with in-hospital mortality.

Methods

A retrospective study was conducted and all patients diagnosed with definite or possible infective endocarditis between January 2013 and June 2018 according to the modified Duke criteria were included.

Results

A total of 381 patients were included. The mean age was 46 years old and 66.9% patients were male patients. Community acquired IE was the most common type of infective endocarditis and Viridans Group Streptococci (37.5%) was still the most common causative pathogen. The microbial etiology of infective endocarditis varied with location of acquisition. 97 (25.5%) patients had culture-negative infective endocarditis. Vegetations were detected in 85% patients and mitral valve was the most common involved valve. Operations were performed in 72.7% patients and in-hospital mortality rate was 8.4%. The risk factors of in-hospital mortality were age old than 70 years old, heart failure, stroke and medical therapy.

Conclusions

Older age, heart failure, stroke and medical therapy were risk factors of in-hospital mortality. Infective endocarditis, were mainly caused by Viridans Group Streptococci, characterized by younger patients and lower mortality rate in China.

Fluorescence in situ hybridization for identification and visualization of microorganisms in infected heart valve tissue as addition to standard diagnostic tests improves diagnosis of endocarditis

OBJECTIVES

In infective endocarditis (IE), identification of the causative organism and consecutive treatment are crucial for patient survival. Although the macroscopic aspect resembles infected tissue, standard diagnostic tests often fail to allow one to identify bacteria. Fluorescence in situ hybridization (FISH) is a molecular, culture-independent technique that allows one to identify and visualize microorganisms within tissue and to recognize their morphology, number and activity. We analysed the diagnostic benefit of FISH/polymerase chain reaction (PCR) by comparing its results to those of standard diagnostic tests.

METHODS

From September 2015 to April 2018, 128 patients underwent first-time or redo valve surgery to treat IE. Patients were designated according to the modified Duke criteria as definite (n = 61), possible (n = 34) or rejected (n = 33) IE. Tissue specimens obtained intraoperatively were analysed using FISH/PCR in addition to undergoing standard diagnostic testing and PCR alone.

RESULTS

We used blood cultures to detect microorganisms in 67/128 patients; valve cultures, in 34/128; PCR, in 67/128; histopathological diagnosis showed IE in 72/128 cases. We were able to detect microorganisms in 103/128 cases using FISH/PCR, with 55/61 in definite IE. Furthermore, we were able to identify 26 cases of bacterial biofilm using FISH/PCR, despite antibiotic treatment of 61 in the definite, 13 in the possible and 1 in the rejected group, including 8/33 patients in the rejected group with active bacteria. In all cases, the patient's therapy was altered.

CONCLUSIONS

FISH/PCR was used to identify microorganisms in cases in which standard diagnostic tests failed to provide sufficient results for various reasons. Furthermore, FISH/PCR enabled us to identify bacterial biofilms and to differentiate between active versus degraded bacteria, thus indicating the impact of treatment. Therefore, we suggest FISH/PCR as an additional diagnostic tool in IE alongside standard diagnostic tests.

Factors Affecting Mortality in Patients with Blood-Culture Negative Infective Endocarditis

Infective endocarditis retains high morbidity and mortality rates despite recent advances in diagnostics, pharmacotherapy, and surgical intervention. Risk stratification in endocarditis patients, including blood-culture negative endocarditis, is crucial in deciding the optimal management strategy; however, the studies investigating risk stratification in these patients were lacking despite the difference with blood-culture positive endocarditis. The aim of this study is to identify risk factors associated with in-hospital mortality in blood-culture negative infective endocarditis patients. A retrospective cohort study was conducted at National Cardiovascular Center Harapan Kita, Jakarta in blood-culture negative infective endocarditis patients from 2013 to 2015. Patient characteristics, clinical parameters, echocardiographic parameters, and clinical complications were collected from medical records and hospital information systems. There were 146 patients that satisfy the inclusion and exclusion criteria out of 162 patients with blood-culture infective endocarditis. The in-hospital mortality rate was 13.5%. On bivariate analyses, factors that were related to in-hospital mortality include New York Heart Association (NYHA) class III and IV heart failure ( p  = 0.007), history of hypertension ( p  = 0.021), stroke during hospitalization ( p  < 0.001), the decline in renal function ( p  < 0.001), and surgery ( p  = 0.028). Variables that were independently associated with mortality upon multivariate analysis were heart failure NYHA functional class III and IV (OR 7.56, p  = 0.011), worsening kidney function (OR 10.23, p  < 0.001), and stroke during hospitalization (OR 8.92, p  = 0.001). Presence of heart failure with NYHA functional class III and IV, worsening kidney function, and stroke during hospitalization were independently associated with in-hospital mortality in blood-culture infective endocarditis patients.

Blood culture-negative endocarditis presenting as altered mental status

Blood culture-negative endocarditis (BCNE) is difficult to diagnose because one of the major criteria to raise suspicion for endocarditis, a positive blood culture, is absent. BCNE accounts for 2.5% to 31% of all cases of endocarditis. Our report describes a 69-year-old woman with end-stage renal disease who presented with altered mental status. Physical examination and testing, including complete blood count, comprehensive metabolic panel, chest X-ray and head CT were otherwise unremarkable. Brain MRI revealed multiple areas of decreased diffusion concerning for cardioembolic stroke. A transthoracic echocardiogram demonstrated an abnormality on the mitral valve. Operative evaluation revealed a purulent mitral valve with vegetative clumps. Cultures of the vegetation and the blood grew no organisms. BCNE is a rare entity; neurological abnormalities may be the only presenting signs/symptoms. Endocarditis should be considered among the causes of altered mental status, even in the absence of positive blood cultures.

Stroke due to non-bacterial thrombotic endocarditis as initial presentation of breast invasive ductal carcinoma

We present a case of a 71-year-old woman with recurrent stroke episodes due to non-bacterial thrombotic endocarditis (NBTE) leading to the diagnosis of an early-stage breast carcinoma. NBTE is associated with a variety of inflammatory states, including malignancy. NBTE presents itself with systemic embolization, mostly stroke. Treatment consists of treating the underlying condition and start of systemic anticoagulation therapy. Cardiac surgery is restricted to highly selected cases, since prognosis usually is limited by the neoplasm, which usually is in an advanced stage at time of diagnosis of NBTE. The malignancy usually is diagnosed prior to NBTE. Cases presenting with NBTE leading to the diagnosis of malignancy, however, are rarely reported. To our knowledge, we present the first case leading to the diagnosis of an early-stage breast carcinoma.

Identification of Dietzia spp. from Cardiac Tissue by 16S rRNA PCR in a Patient with Culture-Negative Device-Associated Endocarditis: A Case Report and Review of the Literature

The genus Dietzia was recently distinguished from other actinomycetes such as Rhodococcus. While these organisms are known to be distributed widely in the environment, over the past decade several novel species have been described and isolated from human clinical specimens. Here we describe the identification of Dietzia natronolimnaea/D. cercidiphylli by PCR amplification and sequencing of the 16S rRNA encoding gene from cardiac tissue in a patient with culture-negative device-associated endocarditis.

Endocarditis: the great mimic of rheumatic diseases

Rheumatic manifestations may be prevalent in more than 30% of patients with infective endocarditis (IE), often predating this diagnosis by several months. A case series of five patients recorded at a tertiary care Rheumatology and Clinical Immunology unit over a period of 1 year emphasises that varied presentations of endocarditis may mimic uncommon rheumatic diseases.

HACEK endocarditis: a review

INTRODUCTION

The HACEK group, referring to Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae, is a rare cause of infective endocarditis (IE). It causes the majority of Gram-negative endocarditis cases and has an excellent prognosis and simple management if properly identified. However, delay in diagnosis and associated complications can render the infection fatal.

AREAS COVERED

Over the past few decades, there have been tremendous advancements in understanding the manifestations and progression of HACEK endocarditis (HE). This review tackles the epidemiology of HE, the microbiological characteristics of each organism in the HACEK group, the methods used to diagnose HE, the clinical manifestations, complications, and mortality of patients with HE, as well as the recommended treatment and preventive methods. Expert Commentary: The lack of robust randomized controlled trials in diagnosis and treatment of HE makes it difficult to determine the optimal management of such infections. Nevertheless, advancements in culturing methods have shown progress in isolating and identifying these fastidious organisms. Positive blood cultures for any of the HACEK organisms in the setting of no definite focus of infection is highly suggestive of HE. In such cases, treatment with ceftriaxone or a fluoroquinolone, even without obtaining antibiotic susceptibilities, should be initiated. Moreover, the decision to proceed with surgical intervention should be individualized. As is the case for other IE, HE requires the collaboration of a multidisciplinary team consisting of the infectious disease specialist, cardiologist, cardiothoracic surgeon, and the microbiologist.

First Case Report of the Antemortem Diagnosis of Nonbacterial Thrombotic Endocarditis of a Mechanical Prosthetic Valve

A 67-year-old man with a history of aortic mechanical valve replacement exhibited an abnormal mass on the sewing ring of the prosthesis on echocardiography. Despite receiving strong anticoagulation, he developed acute cerebral infarction due to the formation of emboli resulting from the thrombus and underwent urgent re-aortic valve replacement. Based on the microscopic findings of the resected mass, he was finally diagnosed as having nonbacterial thrombotic endocarditis (NBTE) of the mechanical prosthetic valve, which was thought to be associated with colorectal cancer. We herein report the first known case of an antemortem diagnosis of NBTE on a mechanical heart valve.

Total Artificial Heart as Bridge to Transplantation for Severe Culture-Negative Prosthetic Valve Endocarditis Due to Gemella haemolysans

We report a rare case of a patient with prosthetic valve endocarditis (PVE) requiring implantation of a total artificial heart (TAH) as a bridge to heart transplantation. Gemella haemolysans, an unusual cause of PVE, was identified as the organism responsible only by 16s rRNA polymerase chain reaction analysis of surgical tissue samples. We also describe one of the first uses of combined TAH and veno-venous extracorporeal membrane oxygenation therapy in the setting of severe respiratory and cardiac failure. Implantation of a TAH may be considered in situations where more traditional reconstructive methods are not feasible.

Infective endocarditis in the military patient

Infective endocarditis (IE) is a potentially fatal cardiac infection associated with an inhospital mortality rate of up to 22%. Fifty per cent of IE cases develop in patients with no known history of valve disease. It is therefore important to remain vigilant to the possibility of the diagnosis in patients with a febrile illness and unknown source. From a military perspective, our patients are unique due to the breadth of pathogens they are exposed to, and blood-culture-negative IE is a risk. In particular, there should be awareness of Coxiella burnetii as a possible causative pathogen. In this review we incorporate the latest consensus from systematic reviews and publications identified by a literature search through Medline. We describe the diagnosis and management of IE with particular reference to the military population.

Infections and cardiovascular disease: is Bartonella henselae contributing to this matter?

Cardiovascular disease is still the major cause of death worldwide despite the remarkable progress in its prevention and treatment. Endothelial progenitor cells (EPCs) have recently emerged as key players of vascular repair and regenerative medicine applied to cardiovascular disease. A large amount of effort has been put into discovering the factors that could aid or impair the number and function of EPCs, and also into characterizing these cells at the molecular level in order to facilitate their therapeutic applications in vascular disease. Interestingly, the major cardiovascular risk factors have been associated with reduced number and function of EPCs. The bacterial contribution to cardiovascular disease represents a long-standing controversy. The discovery that Bartonella henselae can infect and damage EPCs revitalizes the enduring debate about the microbiological contribution to atherosclerosis, thus allowing the hypothesis that this infection could impair the cardiovascular regenerative potential and increase the risk for cardiovascular disease. In this review, we summarize the rationale suggesting that Bartonella henselae could favour atherogenesis by infecting and damaging EPCs, thus reducing their vascular repair potential. These mechanisms suggest a novel link between communicable and non-communicable human diseases, and put forward the possibility that Bartonella henselae could enhance the susceptibility and worsen the prognosis in cardiovascular disease.