Infective endocarditis at autopsy: a review of pathologic manifestations and clinical correlates

From the archives of MD Anderson Cancer Center. Mesothelial/monocytic incidental cardiac excrescence with a review of the literature

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a rare benign lesion composed of monocytes and mesothelial cells that is most often encountered during cardiothoracic surgery. We describe a case in a 71-year-old man with known aortic valve stenosis who presented with gradual onset dyspnea over a few weeks, made worse with minimal exertion. A transesophageal echocardiogram revealed severe aortic stenosis and mild pericardial effusion. The patient underwent aortic valve replacement, coronary artery bypass, and amputation of the left atrial appendage. Histological examination of a 0.8 cm blood clot received along with the atrial appendage showed an aggregation of bland cells with features of monocytes associated with small strands and nodules of mesothelial cells, fat cells, fibrin and a minute fragment of bone. Immunohistochemical analysis showed that the monocytic cells were positive for CD4 and CD68 (strong) and negative for calretinin and keratin. By contrast, the mesothelial cells were positive for calretinin and keratin and negative for all other markers. In sum, the morphologic and immunohistochemical findings support the diagnosis of MICE. Based on our review of the literature, about 60 cases of MICE have been reported previously which we have tabulated. We also discuss the differential diagnosis.

Splenic abscess and infective endocarditis

OBJECTIVE

To determine the background, bacteriological, clinical and radiological findings, associated lesions, treatment and outcome of splenic abscesses (SAs) in infective endocarditis (IE).

METHODS

Retrospective study (2005-2021) of 474 patients with definite IE. The diagnosis of SA was made in 36 (7.6%) patients (31, 86.1%, males, mean age = 51.3) on abdominal CT.

RESULTS

The main implicated organisms were Streptococcus spp (36.1%), Enterococcus faecalis (27.7%), Staphyloccus spp (19.4%). Rare agents were present in 10 patients (27.8%). Pre-existing conditions included a prosthetic valve (19.4%), previous IE (13.9%), intravenous drug use (8.4%), diabetes (25%) alcohol abuse (13.9%), liver disease (5.5%). Vegetations ≥ 15 mm were present in 36.1%. Common presentations were abdominal pain (19.4%) and left-sided pleural effusion (16.5%). SA were more often small (50%; 7 multiple) than large (36.1%; 1 multiple) or microabscesses (13.9%, 3 multiple). Associated complications were extrasplenic abscesses (brain, 11.1%; lung, 5.5%; liver, 2.8%), infectious aneurysms (16.7%: 3 intracranial, 1 splenic, 1 hepatic, 1 popliteal), emboli (brain, 52.8%; spleen, 44.4%, 5 evolving to SA; kidney, 22.2%; aorta, 2.8%), osteoarticular infections (25%). Twenty-eight (77.8%) patients only received antimicrobials, 7 (19.4%) underwent splenectomy, after cardiac surgery in 5. One had percutaneous drainage. The outcome was uneventful (follow-up 3 months-14 years; mean: 17.2 months).

CONCLUSION

In SA-IE patients, the prevalence of vegetation size, Enterococcus faecalis, rare germs, diabetes, osteo-arthritic involvement and cancer was higher than in non-SA patients. Some SAs developed from splenic infarcts. IE-patients with evidence of splenic emboli should be evaluated for a possible abcedation. Cardiac surgery before splenectomy was safe.

A Rare Case of Bivalvular Infective Endocarditis With Left Atrial Mural Endocarditis

Infective endocarditis (IE) is a life-threatening cardiac infection usually associated with cardiac valves. Left atrial (LA) mural endocarditis is rarely seen and occurs in isolation or in conjunction with mitral valve endocarditis. We present a case of a 61-year-old male with no prior cardiac history who presented with melena and fevers. Blood cultures were positive for Enterococcus faecalis. Transesophageal echocardiogram (TEE) demonstrated aortic and mitral valve vegetations with several small echo densities present on the left atrial wall. These findings were further assessed with a computed tomography angiogram of the heart and cardiac magnetic resonance imaging Ti600 sequence. The patient was treated with intravenous antibiotics and underwent aortic and mitral valve replacement with resection of numerous small fungating masses on the left atrium. There are currently no formal guidelines in place for managing mural endocarditis. However, conducting a multidisciplinary evaluation by an endocarditis team could aid in achieving earlier and more precise diagnoses of the underlying condition and its complications. This approach could also ensure consistent antibiotic therapy and appropriate timing for surgical intervention.

Atrioventricular conduction disorders in aortic valve infective endocarditis

BACKGROUND

Aortic valve infective endocarditis may be complicated by high-degree atrioventricular block in up to 10-20% of cases.

AIM

To assess high-degree atrioventricular block occurrence, contributing factors, prognosis and evolution in patients referred for aortic infective endocarditis.

METHODS

Two hundred and five patients referred for aortic valve infective endocarditis between January 2018 and March 2021 were included in this study. A comprehensive assessment of clinical, electrocardiographic, biological, microbiological and imaging data was conducted, with a follow-up carried out over 1 year.

RESULTS

High-degree atrioventricular block occurred in 22 (11%) patients. In univariate analysis, high-degree atrioventricular block was associated with first-degree heart block at admission (odds ratio 3.1; P=0.015), periannular complication on echocardiography (odds ratio 6.9; P<0.001) and severe biological inflammatory syndrome, notably C-reactive protein (127 vs 90mg/L; P=0.011). In-hospital mortality (12.7%) was higher in patients with high-degree atrioventricular block (odds ratio 4.0; P=0.011) in univariate analysis. Of the 16 patients implanted with a permanent pacemaker for high-degree atrioventricular block and interrogated, only four (25%) were dependent on the pacing function at 1-year follow-up.

CONCLUSIONS

High-degree atrioventricular block is associated with high inflammation markers and periannular complications, especially if first-degree heart block is identified at admission. High-degree atrioventricular block is a marker of infectious severity, and tends to raise the in-hospital mortality rate. Systematic assessment of patients admitted for infective endocarditis suspicion, considering these contributing factors, could indicate intensive care unit monitoring or even temporary pacemaker implantation in those at highest risk.

Splenic Embolism in Infective Endocarditis: A Systematic Review of the Literature with an Emphasis on Radiological and Histopathological Diagnoses

Infective endocarditis (IE) is characterised by fever, heart murmurs, and emboli. Splenic emboli are frequent in left-sided IE. A systematic review of the literature published on splenic embolism (SE) between 2000 and 2023 was conducted. Search strategies in electronic databases identified 2751 studies published between 1 January 2000 and 4 October 2023, of which 29 were finally included. The results showed that the imaging tests predominantly used to detect embolisms were computed tomography (CT), magnetic resonance imaging, positron emission tomography (PET)/CT, single-photon emission computed tomography/CT, ultrasound, and contrast-enhanced ultrasound. More recent studies typically used 18F-FDG PET-CT. The proportion of SE ranged from 1.4% to 71.7%. Only seven studies performed systematic conventional CT screening for intra-abdominal emboli, and the weighted mean frequency of SE was 22% (range: 8-34.8%). 18F-FDG PET-CT was performed systematically in seven studies, and splenic uptake was found in a weighted mean of 4.5%. There was a lack of uniformity in the published literature regarding the frequency and management of splenic embolisation. CT scans were the most frequently used method, until recently, when 18F-FDG PET-CT scans began to predominate. More data are necessary regarding the frequency of SE, especially focusing on their impact on IE management and prognosis.

Infective Endocarditis in an Intravenous Drug User Leading to Myocardial Rupture and Hemopericardium

Introduction

Infective endocarditis (IE) is an infectious disorder of the innermost lining of the heart that can be fatal if left untreated. Infective endocarditis can spread beyond the endocardium into the myocardium and cause arrhythmias and myocardial wall rupture. Individuals with a history of intravenous drug use are at increased risk of developing IE and are at higher risk of dying, given their limited access to health care and adherence to treatment.

Methods

A medicolegal autopsy was performed on a 30-year-old woman with a history of intravenous drug use and recent assault after a hospital admission during which she did not survive resuscitation.

Results

The cause of death was found to be myocardial rupture in the setting of transmural IE. Postmortem imaging showed hemopericardium which was identified grossly with valvular vegetations in the heart. A ventricular wall defect along with transmural abscess formation was identified. Perimortem toxicology was positive for fentanyl, methamphetamine, and benzoylecgonine, a metabolite of cocaine. Postmortem blood cultures were positive for coagulase-negative Staphylococci, Staphylococcus aureus, Candida tropicalis, and Viridians group Streptococci. Postmortem tissue cultures taken from the heart was positive for Candida glabrata and Streptococcus mitis.

Discussion

The decedent had significant risk factors for IE, such as intravenous drug use and a prior admission to hospital for IE. The organisms identified on culture are in-keeping with the gross findings of IE and the terminal event of myocardial rupture was likely the result of tissue damage resulting from IE.

Applications of microbiology to different forensic scenarios - A narrative review

In contrast to other forensic disciplines, forensic microbiology is still too often considered a "side activity" and is not able to make a real and concrete contribution to forensic investigations. Indeed, the various application aspects of this discipline still remain a niche activity and, as a result, microbiological investigations are often omitted or only approximated, in part due to poor report in the literature. However, in certain situations, forensic microbiology can prove to be extremely effective, if not crucial, when all other disciplines fail. Precisely because microorganisms can represent forensic evidence, in this narrative review all the major pathological forensic applications described in the literature have been presented. The goal of our review is to highlight the versatility and transversality of microbiology in forensic science and to provide a comprehensive source of literature to refer to when needed.

Left ventricular pseudoaneurysm associated with infective endocarditis: an autopsy case report

Background

Infective endocarditis (IE) is a bacterial infection of the heart valves or endocardium, with complications such as valve perforation, ring abscess, fistula, or damage to the subaortic structures. This case report aims to illustrate an atypical complication of IE which is a pseudoaneurysm depicting a periannular hemorrhage.

Case presentation

We describe a case of a 19-year-old male youth who presented with fever and cough a few days prior to his demise. There was no known risk factor for IE. The autopsy revealed a bulging anterior surface, upper part of the left ventricle which was soft and slightly fluctuant. Cut section of the heart revealed large vegetations affecting the right and left coronary cusps of the aortic valve. The vegetations at the left coronary cusp were mobile, with necrotic and hollow area underneath, appearing like a cavity and containing blood clots. The course of the cavity was determined to be at the periannular region and contained within the myocardium. These findings were consistent with left ventricular pseudoaneurysm. Culture of the vegetations specimen yielded growth of Granulicatella adiacens sp. anti-streptolysin O titre (ASOT) was 400 IU/mL and reported as positive.

Conclusions

IE secondary to Granulicatella sp is rare and may result in catastrophic complications. Therefore, this case report is intended to highlight the autopsy findings of the disease as well as to create awareness of its subtle clinical symptoms.

Laboratory Grown Biofilms of Bacteria Associated with Human Atherosclerotic Carotid Arteries Release Collagenases and Gelatinases during Iron-Induced Dispersion

The association of bacteria with arterial plaque lesions in patients with atherosclerosis has been widely reported. However, the role these bacteria play in the progression of atherosclerosis is still unclear. Previous work in our lab has demonstrated that bacteria exist in carotid artery plaques as biofilm deposits. Biofilms are communities of microorganisms enmeshed within a protective, self-produced extracellular matrix and have been shown to contribute to chronic infections in humans. Biofilm communities have the potential to impact surrounding tissues in an infection if they undergo a dispersion response, releasing bacteria into the surrounding environment by enzymatic degradation of the extracellular matrix. One concern relating to these enzymes is that they could cause collateral damage to host tissues. In this study, we present an in vitro multispecies biofilm culturing model used to investigate the potential role of bacterial biofilm dispersion in the progression of atherosclerosis. This work has demonstrated an increase in cell release from mixed-species biofilms formed by bacteria associated with human carotid arterial plaque deposits following treatment with iron or a combination of norepinephrine and transferrin. Greater extracellular lipase, protease, and collagenase/gelatinase activity was also associated with iron-treated biofilms. The results of this work suggest that bacteria in this model undergo iron-induced biofilm dispersion, as evidenced by the increased cell release and higher enzyme activity following treatment. This work demonstrates the potential for multispecies biofilm dispersion to contribute to arterial tissue degradation by bacteria and suggests that in atherosclerotic infections, biofilm dispersion may contribute to thrombogenesis, which can lead to heart attack or stroke. IMPORTANCE Atherosclerosis, or hardening of the arteries, is a leading cause of congestive heart failure, heart attack, and stroke in humans. Mounting evidence, in the literature and from our lab, points to the regular involvement of bacteria within arterial plaque deposits in patients with advanced atherosclerosis. Very little is known about the behavior of these bacteria and whether they may contribute to tissue damage in infected arteries. Tissue damage within the arterial plaque lesion can lead to rupture of the plaque contents into the bloodstream, where a clot may form, resulting in a potential heart attack or stroke. This study shows that plaque-associated bacteria, when cultured as mixed-species biofilms in the laboratory, can release degradative enzymes into their environment as the result of a dispersion response triggered by iron. These degradative enzymes can digest proteins and lipids which are associated with the tissues that separate the plaque lesion from the arterial lumen. Thus, this study demonstrates that if mixed species biofilms are induced to undergo dispersion in an infected atherosclerotic lesion when exposed to an elevated concentration of free iron, they have the potential to contribute to the weakening of arterial tissues, which may contribute to atherosclerotic plaque destabilization.

Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis

Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.

Solitary 15 cm Splenic Abscess Successfully Treated with Percutaneous Drainage

Splenic abscesses are rare, but can be life-threatening. Antibiotics, percutaneous drainage and splenectomy are the usual treatment options. However, there is no ideal algorithm for choosing among these options. A man in his 60 s presented with 10 days of left upper quadrant pain and abdominal distension. Computed tomography (CT) scan of the abdomen revealed a splenic abscess measuring 15 cm in diameter. Transesophageal echocardiography confirmed the diagnosis of infectious endocarditis. Ultrasound-guided percutaneous drainage was performed and Streptococcus anginosus grew in cultures of both blood and intrasplenic fluid. The patient was treated with intravenous antibiotics and continuous drainage for 8 weeks. The abscess cavity nearly disappeared on follow-up CT scan. Percutaneous drainage should be considered for a solitary unilocular splenic abscess even if the abscess is large.

Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome

Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.

Ultrastructural mitral valve abnormalities in infective endocarditis

Aim. Using an original method based on backscattered scanning electron microscopy, to study the structural features of the mitral valve leaflets in infective endocarditis.

Material and methods. We examined 9 mitral valves extracted during surgical interventions due to structural malfunction in patients with infective endocarditis (IE). The samples were fixed in buffered paraformaldehyde with osmium tetraoxide postfixation. After dehydration by increasing alcohol concentration and acetone, the samples were placed in epoxy resin. After the resin has polymerized, the samples were ground and then polished to the desired depth. To increase the electronic contrast, the samples were treated with a uranyl acetate alcohol solution during dehydration and with Reynolds' lead citrate after polishing the epoxy blocks. The samples were visualized by backscattered scanning electron microscopy at an accelerating 15-kV voltage.

Results. Structural leaflet injuries caused by IE were most pronounced in the central part and the base. Necrotic areas were extensive electron-dense formations located in the central leaflet layers, or displaced towards the ventricular surface. The electron-dense material in the necrotic area was poorly structured and contained individual cells and bacteria. Bacteria were also present outside the necrotic area. Necrotic areas were surrounded by a layer of a modified extracellular matrix, usually covered with a fibrin layer. Among the extracellular matrix fibers, the macrophages, smooth myocytes and fibroblasts was noted. The fibrin layer, in addition to these cells, contained a large number of blood vessels and was often covered with endothelium.

Conclusion. Infection of the mitral valve leaflets causes a simultaneous inflammatory response and regeneration activation. Without adequate regulatory factors, the processes of inflammation and connective tissue creation lead to structural and functional leaflet failure. Specific causes may be overgrowth of necrotic and inflammatory areas, edema and fiber orientation disorder, as well as leaflet rupture.

Bacterial biofilms in infective endocarditis: an in vitro model to investigate emerging technologies of antimicrobial cardiovascular device coatings

Objective

In spite of the progress in antimicrobial and surgical therapy, infective endocarditis (IE) is still associated with a high morbidity and mortality. IE is characterized by bacterial biofilms of the endocardium, especially of the aortic and mitral valve leading to their destruction. About one quarter of patients with formal surgery indication cannot undergo surgery. This group of patients needs further options of therapy, but due to a lack of models for IE prospects of research are low. Therefore, the purpose of this project was to establish an in vitro model of infective endocarditis to allow growth of bacterial biofilms on porcine aortic valves, serving as baseline for further research.

Methods and results

A pulsatile two-chamber circulation model was constructed that kept native porcine aortic valves under sterile, physiologic hemodynamic and temperature conditions. To create biofilms on porcine aortic valves the system was inoculated with Staphylococcus epidermidis PIA 8400. Aortic roots were incubated in the model for increasing periods of time (24 h and 40 h) and bacterial titration (1.5 × 10⁴ CFU/mL and 1.5 × 10⁵ CFU/mL) with 5 L cardiac output per minute. After incubation, tissue sections were analysed by fluorescence in situ hybridization (FISH) for direct visualization of the biofilms. Pilot tests for biofilm growth showed monospecies colonization consisting of cocci with time- and inocula-dependent increase after 24 h and 40 h (n = 4). In n = 3 experiments for 24 h, with the same inocula, FISH visualized biofilms with ribosome-containing, and thus metabolic active cocci, tissue infiltration and similar colonization pattern as observed by the FISH in human IE heart valves infected by S. epidermidis.

Conclusion

These results demonstrate the establishment of a novel in vitro model for bacterial biofilm growth on porcine aortic roots mimicking IE. The model will allow to identify predilection sites of valves for bacterial adhesion and biofilm growth and it may serve as baseline for further research on IE therapy and prevention, e.g. the development of antimicrobial transcatheter approaches to IE.

Graphic abstract

Widespread septic embolization in injection drug use mitro-aortic infective endocarditis as a remote cause of death

Injection drug use-related infective endocarditis (IDU-IE) assumes peculiar epidemiological, pathogenetic, and prognostic characteristics that allow to consider it a distinct nosological entity, as well as a current problem of considerable social weight. Incidence is reasonably underestimated because diagnosis is often accidental in postmortem examination when drug-related death is suspected. In many cases, postmortem toxicological examinations are negative for acute drug abuse, and findings of infective endocarditis became relevant in the explanation of the mechanism of death. Extracardiac involvement of infective endocarditis is rarely reported as fatal. Fragmentation and embolization of bacterial vegetations can be associated with parenchymal infarcts, systemic spread of the infectious process by formation of an abscess. A case of septic shock as a consequence of the constant bacteremia determined by the continuous proliferation and release of bacteria into the circulation is presented in an injection drug user with left-sided endocarditis and widespread septic embolization. Authors reviewed forensic and medical literature and promote epidemiological value of medical and forensic autopsy. Extracardiac involvement of infective endocarditis may represent a remote and alternative cause of death in injection drug users, and an early diagnosis can be relevant for prognosis. Postmortem examination still represents a valuable opportunity of learning for clinicians and improving diagnostic accuracy with injection drug users. A call for changing of attitudes and practice toward autopsy is finally demanded.

Coagulation: At the heart of infective endocarditis

Infective endocarditis is a life-threatening and enigmatic disease with a mortality of 30% and a pathophysiology that is poorly understood. However, at its core, an endocarditis lesion is mainly a fibrin and platelet blood clot infested with bacteria, clinging at the cardiac valves. Infective endocarditis therefore serves as a paradigm of immunothrombosis gone wrong. Immunothrombosis refers to the entanglement of the coagulation system with innate immunity and the role of coagulation in the isolation and clearance of invading pathogens. However, in the case of infective endocarditis, instead of containing the infection, immunothrombosis inadvertently creates the optimal shelter from the immune system and allows some bacteria to grow almost unimpeded. In every step of the disease, the coagulation system is heavily involved. It mediates the initial adhesion of bacteria to the leaflets, fuels the growth and maturation of a vegetation, and facilitates complications such as embolization and valve destruction. In addition, the number one cause of infective endocarditis, Staphylococcus aureus, has proven to be a true manipulator of immunothrombosis and thrives in the fibrin rich environment of an endocarditis vegetation. Considering its central role in infective endocarditis, the coagulation system is an attractive therapeutic target for this deadly disease. There is, however, a very delicate balance at play and the use of antithrombotic drugs in patients with endocarditis is often accompanied with a high bleeding risk.

Overview and Comparison of Infectious Endocarditis and Non-infectious Endocarditis: A Review of 814 Autoptic Cases

AIM

We examined evidence on infective and non-infective endocarditis obtained from a database of 50,403 clinical autopsies performed at an Italian general hospital between January 1983 and December 2006.

MATERIALS AND METHODS

Out of 814 endocarditis cases, 409 were of infective endocarditis (IE) and 405 non-infective (NIE). The median age at the time of death was 78 years for those with IE and 83 for those with NIE. Data were collected on gender, clinical history, comorbidities, kind of affected valve (non-prosthetic/mechanical/biological), pathological features of endocarditis, endocarditis complications and microbiological agents.

RESULTS

The diagnosis of IE was frequently missed and these conditions were often complicated by cardiovascular events. IE was more common among patients with prior valve infection or cardiovascular surgery, while malignancies were frequent comorbidities of NIE.

CONCLUSION

In general, we found several data that differ from those generally present in the scientific literature, and this could be explained by the fact that data on IE and NIE are generally obtained from surgical and clinical databases, while we analysed only autoptic cases.

Associations between echocardiographic manifestations and bacterial species in patients with infective endocarditis: a cohort study

Background

The diagnosis of infective endocarditis (IE) is based on microbiological analyses and diagnostic imaging of cardiac manifestations. Echocardiography (ECHO) is preferred for visualization of IE-induced cardiac manifestations. We investigated associations between bacterial infections and IE manifestations diagnosed by ECHO.

Methods

In this cohort study, data from patients aged 18 years or above, with definite IE admitted at the Karolinska University Hospital between 2008 and 2017 were obtained from Swedish National Registry of Endocarditis. Bacteria registered as pathogen were primarily selected from positive blood culture and for patients with negative blood culture, bacteria found in culture or PCR from postoperative material was registered as pathogen. Patients with negative results from culture or PCR, and patients who did not undergo ECHO during hospital stay, were excluded. IE manifestations diagnosed by ECHO were obtained from the registry. Chi-squared test and two-sided Fisher’s exact test was used for comparisons between categorical variables, and student’s t test was used for continuous numerical variables. Multivariable analyses were performed using logistic regression. Secular trend analyses were performed using linear regression. Associations and the strength between the variables were estimated using odds ratios (ORs) with 95% confidence intervals (CIs). P < 0.05 was considered significant.

Results

The most common bacteria were Staphylococcus aureus (n = 239, 49%) and viridans group streptococci (n = 102, 21%). The most common manifestations were vegetation in the mitral (n = 195, 40%), aortic (n = 190, 39%), and tricuspid valves (n = 108, 22%). Associations were seen between aortic valve vegetations and Enterococcus faecalis among patients with native aortic valves, between mitral valve vegetations and streptococci of group B or viridans group, between tricuspid valve vegetations and S. aureus among patients with intravenous drug abuse, and between perivalvular abscesses as well as cardiovascular implantable electronic device (CIED)-associated IE and coagulase negative staphylococci (all P < 0.05).

Conclusions

Associations were found between certain bacterial species and specific ECHO manifestations. Our study contributes to a better understanding of IE manifestations and their underlying bacterial etiology, which pathogens can cause severe infections and might require close follow-up and surgical treatment.

Characteristics and outcomes of patients with right-sided endocarditis undergoing cardiac surgery

Background

There has been an increasing incidence of right-sided infective endocarditis (RSIE) due to the global rise of intravenous drug use (IVDU) and an increasing number of implantable cardiac electronic devices and central venous catheters. Our aim was to investigate differences in the clinical presentation, microbiological findings and prognosis of patients undergoing surgery for RSIE compared to left-sided infective endocarditis (LSIE).

Methods

Relevant clinical data of all 432 consecutive patients undergoing valve surgery for infective endocarditis (IE) at our institution between January 2009 and December 2018 were retrospectively analyzed. Acquired data included patients' demographic and preoperative comorbidities, manifestation of IE according to the recently modified Duke Criteria, perioperative data and relevant clinical outcomes.

Results

A total of 403 patients (93.3%) underwent surgery for LSIE and twenty-nine patients (6.7%) for RSIE. Eleven patients with RSIE (37.9%) showed a concomitant left-sided infection. Compared to LSIE, RSIE patients were significantly younger [47.5 (40.4-69.3) vs. 65.1 (53.7-74.6); P=0.008] and presented with less comorbidities such as hypertension (41.4% vs. 65.3%; P=0.010) and coronary artery disease (6.9% vs. 29.0%; P=0.010). Rates of IVDU (34.5% vs. 4.5%; P<0.001), human immunodeficiency virus (HIV) (10.3% vs. 1.7%; P=0.023) and hepatitis C virus (HCV) infection (24.1% vs. 5.2%; P=0.001) were greater in RSIE. The proportion of Staphylococcus aureus IE was significantly higher in RSIE compared to LSIE (37.9% vs. 21.1%; P=0.035). 30-day mortality was 6.9% after surgery for RSIE compared to 14.6% after operation for LSIE (P=0.372).

Conclusions

Patients undergoing surgery for RSIE compared to LSIE presented with a higher rate of pulmonary septic emboli, more Staphylococcus aureus infections and larger vegetations. Larger multicenter prospective trials are needed to provide more reliable data on the clinical profile of these patients, in order to determine optimal surgical management.

Aspergillus endocarditis diagnosed by fungemia plus serum antigen testing

Fungal endocarditis remains an uncommon clinical diagnosis, though is likely to become more frequent due to the global increase in transplantations and cardiac valvular surgery. A case of prosthetic valve endocarditis due to Aspergillus fumigatus is described that was diagnosed with serologic fungal markers and confirmed with positive blood cultures, an uncommon finding.

Detection of spleen, kidney and liver infarcts by abdominal computed tomography does not affect the outcome in patients with left-side infective endocarditis

Extra-cardiac abdominal complications are common in left-side infective endocarditis (LS-IE). The aim of this work was to study whether patients with LS-IE presenting splenic, renal, or liver (SRL) involvement seen in abdominal computed tomography (CT) had different clinical features, therapeutic plans, and outcome than those without these findings on CT.From January 2008 to April 2010, multidisciplinary teams have prospectively collected all consecutive cases of IE, diagnosed according to the Duke criteria, in which abdominal CT was performed.A total of 147 patients with LS-IE had abdominal CT. Fifty (34%) had SRL lesions: 46 splenic, 15 renal, 1 liver infarct, and 2 liver abscesses. Patients with SRL lesions were mainly men (P = .01), had liver disease (P = .001) with natural valve (P = .050) and mitro-aortic valve involvement (P = .042), splenomegaly (P = .001), nonabdominal emboli (P = .001), and a greater number and larger vegetation (>15 mm, P = .049) in the mitro-aortic valves (P = .051) than patients with normal abdominal CT. The site of acquisition, clinical characteristics, microbiology, surgical treatment, days of hospitalization, hospital death, and 1-year mortality were similar in patients with and without SRL emboli on CT. In the stepwise logistic regression analysis, male gender (odds ratio [OR] = 3.6, 95% confidence interval [CI] = 1.4-9.1), liver disease (OR = 8.3, 95% CI = 2.1-31.8), and nonabdominal emboli (OR = 5.2, 95% CI = 2.3-11.7) were independently associated with SRL lesions.Male patients with native LS-IE who had liver disease and nonabdominal emboli had more frequent abdominal lesions seen on CT. The presence of SRL infarcts on abdominal CT scan performed on patients with LS-IE seems to have poor practical implications, and as a consequence, its realization should only be considered when there are symptoms or signs that suggest them.

Serine-Rich Repeat Adhesins Mediate Shear-Enhanced Streptococcal Binding to Platelets

The binding of bacteria to platelets is thought to be a central event in the pathogenesis of infective endocarditis. The serine-rich repeat (SRR) glycoproteins of viridans group streptococci have been shown to mediate platelet binding in vitro and to contribute to virulence in animal models. However, it is not known whether SRR adhesins can mediate streptococcal binding under the high fluidic shear stress conditions present on the endocardial surface. We found that three streptococcal SRR adhesins (GspB, Hsa, and SrpA) with differing structures and sialoglycan binding specificities nevertheless exhibited similar biomechanical properties. All three adhesins mediated shear-enhanced streptococcal binding to immobilized platelets through the platelet receptor GPIbα. Shear-enhanced adhesion was manifested in three ways. First, the number of circulating streptococci binding via SRR adhesins to immobilized platelet receptors peaked at 1 dyn/cm² Second, bound streptococci switched from weak rolling to strong stationary adhesion as shear stress increased to 10 dyn/cm² Third, while a few streptococci detached each time the flow was increased, the majority of streptococci bound to platelets remained firmly attached through 20 to 80 dyn/cm² (shear levels typical of arteries and the endocardium). Thus, all three adhesins mediated shear-enhanced streptococcal binding to platelets under the flow conditions found in heart valves. The ability of the SRR adhesins to mediate shear-enhanced binding strongly suggests that they form catch bonds that are activated by tensile force and provides a mechanism for the selective targeting of bacteria to platelet receptors immobilized on the endocardial surface.

Fungal Endocarditis

Fungal endocarditis is a rare and fatal condition. The Candida and Aspergillus species are the two most common etiologic fungi found responsible for fungal endocarditis. Fever and changing heart murmur are the most common clinical manifestations. Some patients may have a fever of unknown origin as the onset symptom. The diagnosis of fungal endocarditis is challenging, and diagnosis of prosthetic valve fungal endocarditis is extremely difficult. The optimum antifungal therapy still remains debatable. Treating Candida endocarditis can be difficult because the Candida species can form biofilms on native and prosthetic heart valves. Combined treatment appears superior to monotherapy. Combination of antifungal therapy and surgical debridement might bring about better prognosis.

Restructuring of Enterococcus faecalis biofilm architecture in response to antibiotic-induced stress

Bacterial biofilms are intrinsically resistant to antimicrobial treatment, which contributes to microbial persistence in clinical infections. Enterococcus faecalis is an opportunistic pathogen that readily forms biofilms and is the most prevalent enterococcal species identified in healthcare-associated infections. Since intrinsic resistance to multiple antibiotics is common for enterococci, and antibiotic resistance is elevated in biofilm populations, it is imperative to understand the mechanisms involved. Previously, we identified two glycosyltransferase genes whose disruption resulted in impaired nascent biofilm formation in the presence of antibiotic concentrations subinhibitory for parent growth and biofilm formation. The glycosyltransferases are involved in synthesis of the cell-wall-associated rhamnopolysaccharide Epa. Here we examined the effect of epa mutations on the temporal development of E. faecalis biofilms, and on the effects of antibiotics on pre-formed biofilms using scanning electron microscopy. We show that ΔepaOX mutant cells arrange into complex multidimensional biofilms independent of antibiotic exposure, while parent cells form biofilms that are monolayers in the absence of antibiotics. Remarkably, upon exposure to antibiotics parent biofilm cells restructure into complex three-dimensional biofilms resembling those of the ΔepaOX mutant without antibiotics. All biofilms exhibiting complex cellular architectures were less structurally stable than monolayer biofilms, with the biofilm cells exhibiting increased detachment. Our results indicate that E. faecalis biofilms restructure in response to cellular stress whether induced by antibiotics in the case of parent cells, or by deficiencies in Epa composition for the ΔepaOX strain. The data demonstrate a link between cellular architecture and antibiotic resistance of E. faecalis biofilms.

Studying how the architecture of bacterial biofilms can change on exposure to antibiotics could help tackle persistent clinical infections. Enterococcus faecalis is one of the most prevalent bacteria involved in healthcare situations. Its resistance to antibiotics is elevated by the formation of biofilms. Gary Dunny and colleagues at the University of Minnesota, USA studied genetic factors related to the response of E. faecalis biofilms to antibiotics. They identified mutations that caused the bacterial cells to produce structurally altered biofilms and found that similar structural alterations were induced in biofilms made by normal cells in the presence of antibiotics. The altered architecture can make the biofilms less stable and therefore more easily disrupted by treatments. Learning more about the mechanisms underlying these structural changes in biofilms might lead to new options in treating antibiotic resistant infections.

Fatal endocarditis with methicilin-sensible Staphylococcus aureus and major complications: rhabdomyolysis, pericarditis, and intracerebral hematoma: A case report and review of the literature

BACKGROUND

Over the last decades Staphylococcus aureus (SA) has become the dominant etiology of native valve infective endocarditis, with the community-acquired methicillin-sensible Staphylococcus aureus (CA-MSSA) strains being the prevailing type.

CASE

We report here a case of extremely severe CA-MSSA aortic valve acute endocarditis associated with persistent Staphylococcus aureus bacteremia (SAB) in a previously healthy man and include a literature review.The patient developed severe and rare complications (purpura, purulent pericarditis, intracerebral hematoma, and rhabdomyolysis) through systemic embolism; they required drainage of pericardial empyema and cerebral hematoma, the latter eventually caused a fatal outcome. The strains recovered from sequential blood culture sets and pericardial fluid were MSSA negative for genes encoding for staphylococcal toxic shock syndrome toxin (TSST)-1 and Panton-Valentine leukocidin. C, G, and I enterotoxin genes were detected.

CONCLUSIONS

This case with unusually severe evolution underlines the limited ability of vancomycin to control some MSSA infections, possibly due to potential involvement of SA virulence factors, hence the importance of clinical vigilance for community SAB cases.

Inflammation and cardiac insufficiency associated with infectious endocarditis

The study included 62 patients with uncomplicated primary and secondary infectious endocarditis admitted to S.P. Botkin city hospital from 2011 to 2014. The emphasis is laid on diagnostic significance of dynamic measurements of the levels of C-reactive protein, tumour necrosis factor, and highly sensitive troponin-1 for the evaluation of activity of the infectious/toxic process, severity of the disease, and detection of complications. The study revealed the relationship of the enhanced level of troponin-1 with changes of inflammation markers, morphofunctional characteristics of myocardium, and circulatory failure. Morphologicl study demonstrated inflammatory and dystrophic changes in myocardium, focal and diffuse cardiofibrosis suggesting development ofnon-coronarogenic myocardial lesions that play an important role in the progress of cardiac failure associated with infectious endocarditis.

Infective Endocarditis Presenting as Complete Heart Block With an Unexpected Finding of a Cardiac Abscess and Purulent Pericarditis

Intracardiac abscess resulting in complete heart block is an infrequent complication of infective endocarditis. Most presentations of endocarditis are limited to valvular and perivalvular structures, with varying degrees of heart block occurring in the minority of cases. We report a case of endocarditis manifesting as chest pain associated with ST segment elevation and complete heart block. The patient expired unexpectedly within a few hours of presentation. Postmortem examination revealed an atrial septal abscess, purulent pericardial collection, and fibrinous pericarditis. Spread of the abscess into the atrial septum was postulated to be the cause of the complete heart block. In endocarditis, the ominous development of heart block and a poor response to antibiotic therapy imply significant extension of the infection. Management therefore requires prompt ventricular pacing with consideration for valve replacement and possible pericardial drainage.

Fungal Endocarditis in Neonates: A Review of Seventy-one Cases (1971-2013)

BACKGROUND

Fungal endocarditis (FE) remains an uncommon but life-threatening complication of invasive fungal infections. As data on neonatal FE are scant, we aimed to review all published experience regarding this serious infection.

METHODS

Neonatal FE cases published in PubMed (1971-2013) as single cases, or case series were identified using the terms "fungal endocarditis, neonates and cardiac vegetation." Data on predefined criteria including demographics, predisposing factors, mycology, sites of cardiac involvement, therapy and outcome were collected and analyzed.

RESULTS

The dataset comprised 71 neonates with FE. Median birth weight was 940 g [interquartile range (IQR): 609], median gestational age 27 weeks (IQR: 6) and median postnatal age at diagnosis 20 days (IQR: 20). Ninety-two percent of the patients were premature. Right atrium was the most common vegetation site (63%). Seventy-one percent of the cases reported were associated with previous central venous catheters. Candida albicans was the most predominant fungal species (59%). Amphotericin B monotherapy was used in 42.2% and fluconazole in 2.8%. Amphotericin B with flucytosine (25.3%) was the most frequent combined regimen. Surgical treatment was conducted in 28%. Overall mortality was 42.2%. Initiation with combined antifungal treatment was associated with lower mortality than monotherapy (24.2% vs. 51.7%, respectively, P = 0.036).

CONCLUSIONS

Neonatal FE most frequently occurs in very premature infants and is associated with central venous catheters. C. albicans is the predominant fungus. Although outcome has been dismal, it may be improved with combined antifungal therapy.

Update on endocarditis-associated glomerulonephritis

Glomerulonephritis (GN) due to infective endocarditis (IE) is well documented, but most available data are based on old autopsy series. To update information, we now present the largest biopsy-based clinicopathologic series on IE-associated GN. The study group included 49 patients (male-to-female ratio of 3.5:1) with a mean age of 48 years. The most common presenting feature was acute kidney injury. Over half of the patients had no known prior cardiac abnormality. However, the most common comorbidities were cardiac valve disease (30%), intravenous drug use (29%), hepatitis C (20%), and diabetes (18%). The cardiac valve infected was tricuspid in 43%, mitral in 33%, and aortic in 29% of patients. The two most common infective bacteria were Staphylococcus (53%) and Streptococcus (23%). Hypocomplementemia was found in 56% of patients tested and ANCA antibody in 28%. The most common biopsy finding was necrotizing and crescentic GN (53%), followed by endocapillary proliferative GN (37%). C3 deposition was prominent in all cases, whereas IgG deposition was seen in <30% of cases. Most patients had immune deposits detectable by electron microscopy. Thus, IE-associated GN most commonly presents with AKI and complicates staphylococcal tricuspid valve infection. Contrary to infection-associated glomerulonephritis in general, the most common pattern of glomerular injury in IE-associated glomerulonephritis was necrotizing and crescentic glomerulonephritis.

The short life of an aortic cusp aneurysm: a case report

This report describes a 42-year-old man with a history of lymphoma who is admitted with symptoms of chest pain, ST elevation changes, and elevated troponins. Immediate bedside echocardiographic evaluation led to an aborted urgent coronary angiography and a diagnosis of presumed endocarditis. Transesophageal echocardiography (TTE) subsequently revealed an aortic noncoronary cusp aneurysm masking as vegetation. The rapid assessment by TTE and transesophageal echocardiogram prevented an alternate course for this patient's management. We reviewed the necessity of heart catheterization in patients with significantly elevated troponins, pericarditis symptoms, and the rare sighting of aortic valve cusp aneurysms.

Temporal and stochastic control of Staphylococcus aureus biofilm development

Biofilm communities contain distinct microniches that result in metabolic heterogeneity and variability in gene expression. Previously, these niches were visualized within Staphylococcus aureus biofilms by observing differential expression of the cid and lrg operons during tower formation. In the present study, we examined early biofilm development and identified two new stages (designated “multiplication” and “exodus”) that were associated with changes in matrix composition and a distinct reorganization of the cells as the biofilm matured. The initial attachment and multiplication stages were shown to be protease sensitive but independent of most cell surface-associated proteins. Interestingly, after 6 h of growth, an exodus of the biofilm population that followed the transition of the biofilm to DNase I sensitivity was demonstrated. Furthermore, disruption of the gene encoding staphylococcal nuclease (nuc) abrogated this exodus event, causing hyperproliferation of the biofilm and disrupting normal tower development. Immediately prior to the exodus event, S. aureus cells carrying a nuc::gfp promoter fusion demonstrated Sae-dependent expression but only in an apparently random subpopulation of cells. In contrast to the existing model for tower development in S. aureus, the results of this study suggest the presence of a Sae-controlled nuclease-mediated exodus of biofilm cells that is required for the development of tower structures. Furthermore, these studies indicate that the differential expression of nuc during biofilm development is subject to stochastic regulatory mechanisms that are independent of the formation of metabolic microniches.

In this study, we provide a novel view of four early stages of biofilm formation by the human pathogen Staphylococcus aureus. We identified an initial nucleoprotein matrix during biofilm development that is DNase I insensitive until a critical point when a nuclease-mediated exodus of the population is induced prior to tower formation. Unlike the previously described dispersal of cells that occurs after tower development, we found that the mechanism controlling this exodus event is dependent on the Sae regulatory system and independent of Agr. In addition, we revealed that the gene encoding the secreted staphylococcal nuclease was expressed in only a subpopulation of cells, consistent with a model in which biofilms exhibit multicellular characteristics, including the presence of specialized cells and a division of labor that imparts functional consequences to the remainder of the population.

Evaluation with contrast ultrasound of the prevalence of splenic infarction in left-sided infective endocarditis

PURPOSE

To prospectively evaluate the prevalence of the embolization of the spleen in patients with definite left-sided infective endocarditis (IE) using a contrast-enhanced ultrasound (CEUS).

METHODS

From March 2012 through September 2013, 18 consecutive patients (9 females and 9 males, aged 21-83 years) evaluated at our hospital and with definite left-sided IE according to the revised Duke criteria were enrolled. All of the patients gave informed written consent and the study was performed in conformity with the ethical guidelines of the Declaration of Helsinki. All of the patients were submitted to a CEUS of the spleen within 10 days after the definite diagnosis of IE. For the CEUS, a blood pool second-generation contrast agent and an ultrasound machine with a contrast harmonic imaging technology were used.

RESULTS

The splenic CEUS showed infarctions in 11 patients (61 %) and resulted positive in the 2 patients with negative echocardiography.

CONCLUSIONS

In this study, CEUS of the spleen, a repeatable and low-cost imaging technique, easily allowed the bedside detection of asymptomatic and even tiny infarctions and showed a high rate of embolization in patients with definite left-sided IE. Therefore, in the setting of IE (possible or definite), CEUS of the spleen has the potential to better define or accelerate the diagnosis itself.

Acute rupture of chordae tendineae of the mitral valve in infants: a nationwide survey in Japan exploring a new syndrome

BACKGROUND

Recently, infant cases of acute heart failure attributable to rupture of the mitral chordae tendineae have been reported. However, little is known about the pathogenesis and clinical course of this condition.

METHODS AND RESULTS

Ninety-five children with rupture of mitral chordae tendineae were identified in nationwide surveys of Japan diagnosed from 1995 to 2013. The clinical manifestations, management strategies, and prognosis were investigated. Eighty-one (85%) patients were between 4 and 6 months (median, 5 months) of age. In 63 (66%) patients, rupture occurred during the spring or summer. The underlying conditions before rupture included Kawasaki disease (10 cases), maternally derived anti-SSA antibodies (2 cases), and infective endocarditis (1 case). Surgery was performed in 80 patients (94 operations), and the final operations included plasty of mitral chordae in 52 cases and mechanical valve replacement in 26 cases. The histopathologic examinations of the mitral valves and chordae (n=28) revealed inflammatory reactions with predominant mononuclear cell infiltration in 18 cases (64%) and increased fibrous and myxoid tissue in 11 cases (39%), suggesting that nonbacterial infectious or autoimmune endocarditis and myxoid changes are involved in the pathogenesis. Eight patients (8.4%) died before (n=6) and shortly after (n=2) the operation, and significant neurological complications persisted in 10 cases (11%).

CONCLUSIONS

Acute heart failure attributable to rupture of the mitral chordae tendineae in infants is a unique disease resulting from diverse causes. This condition should be recognized as a significant cardiovascular disorder that may cause sudden onset of cardiogenic shock and death in infants.

Concomitant infection of the tricuspid valve and right ventricle free wall after chest tube insertion in a young patient without predisposing diseases

Infective endocarditis (IE) is one of the most dreaded complications of healthcare-associated bloodstream infection. It is an important and potentially lethal complication of medical care and there is incidence evidence of it in this population. We describe a case of concomitant infection of the tricuspid valve and right ventricle free wall after chest tube insertion for spontaneous pneumothorax in a young patient without predisposing diseases.

Euthermic endocarditis

Background

Most patients with infective endocarditis (IE) manifest fever. Comparison of endocarditis patients with and without fever, and whether the lack of fever in IE is a marker for poorer outcomes, such as demonstrated in other severe infectious diseases, have not been defined.

Methods and Results

Cases from the Mayo Clinic, Rochester, Minnesota, Division of Infectious Diseases IE registry, a single-center database that contains all cases of IE treated at our center. Diagnosis date between 1970 and 2006, which met the modified Duke criteria for definite endocarditis, without fever was included. There were 240 euthermic endocarditis cases included in this analysis, with 282 febrile controls selected by frequency matching on gender and decade of diagnosis. Euthermic patients had a median age of 63.6 years (±16.1) as compared to 59.0 years (±16.4) in the febrile control group (p=0.001). Median (IQR) symptom duration prior to diagnosis was 4.0 (1.0, 12.0) weeks in the euthermic group compared to 3.0 (1.0, 8.0) weeks in the febrile controls (p= 0.006). From unadjusted analyses, survival rates were 87% in euthermic cases versus 83% in febrile controls across 28-day follow-up (p=0.164), and 72% in euthermic group cases versus 69% in febrile controls across 1-year follow-up (p=0.345). Also unadjusted, the 1-year cumulative incidence rate of valve surgery was higher in euthermic cases versus febrile controls (50% vs. 39%, p= 0.004).

Conclusions

Patients with euthermic endocarditis are older, and lack of fever was associated with longer symptom duration and delayed diagnosis prior to IE diagnosis. Despite a higher unadjusted rate of valve surgery in euthermic patients, the result was not significant when adjusting for baseline confounders. Differences in survival rates at both 28-days and 365-days were not statistically significant between the two groups.

Contrast-enhanced ultrasound evaluation of splenic embolization in patients with definite left-sided infective endocarditis

The purpose of the study described here was to prospectively evaluate the significance of embolization of the spleen in patients with definite left-sided infective endocarditis (IE) using contrast-enhanced ultrasound (CEUS). From March through October 2012, 6 consecutive patients (4 females and 2 males, aged 27 to 83 years) with definite left-sided IE according to the revised Duke criteria were enrolled. All patients gave informed written consent, and the study was performed in conformity with the ethical guidelines of the Declaration of Helsinki. All patients underwent CEUS of the spleen within 1 week of the definite diagnosis of IE. A blood pool second-generation contrast agent and an ultrasound machine with contrast harmonic imaging technology were used for CEUS. Fifteen consecutive patients (7 females and 8 males, aged 39 to 88 years) who underwent CEUS from October through November 2012 for the study of focal liver lesions constituted the control group. The number of patients did not permit statistical analysis. Splenic CEUS revealed infarctions in 5 patients and an infarcted area in the only patient with negative echocardiography. All splenic CEUS procedures in the control group were negative. In this study, CEUS of the spleen, a repeatable and low-cost imaging technique, easily allowed bedside detection of asymptomatic and even tiny infarctions, and revealed a high rate of embolization in patients with definite left-sided IE. Indeed, splenic CEUS, if applied to the workup of patients with suspect IE, has the potential to accelerate or upgrade the diagnosis itself.

Infective endocarditis: a history of the development of its understanding

Inflammation of the inner layer of the heart, especially the valvular endothelium, chordae tendinae and mural endocardium was first recognized almost 350 years ago. Over the years it has had many names, but is now generally designated infective endocarditis (IE) and has an associated infectious agent. A sterile vegetative process can also affect the valves and is usually referred to as Libman-Sacks endocarditis. The developments of medical science that allowed for our understanding of this entity included refinement of the autopsy, medical microscopy, microbiology, and in recent years, molecular studies. Some observations were misleading but clarification particularly followed the reports of Morgagni, Osler and Libman. As understanding of the pathobiology of infective endocarditis grew so did the effectiveness of therapy. This paper provides a detailed history of the development of the concept of Infective endocarditis citing many key morphological observations and concludes with brief comments about current concepts of pathogenesis as well as a few remarks about therapy.

Native valve right sided infective endocarditis

Right-sided infective endocarditis (RSIE) accounts for 5-10% of all cases of infective endocarditis (IE), and is predominantly encountered in the injecting drug user (IDU) population, where HIV and HCV coinfections often coexist. Staphylococcus aureus is the most common pathogen. The pathogenesis of RSIE is still not well understood. RSIE usually presents as a persistent fever with respiratory symptoms whilst signs of systemic embolisation as seen in left-sided IE are notably absent. The prompt diagnosis of RSIE thus requires a high index of suspicion. Transthoracic echocardiography (TTE) can detect the majority of RSIE, whilst transoesophageal echocardiography (TOE) can increase sensitivity. Virulence of the causative organism and vegetation size are the major determinants of prognosis. Most cases of RSIE resolve with appropriate antibiotic administration.

Spleen rupture associated with septic emboli and endocarditis in a hemodialysis patient

We present an uremic patient on chronic hemodialysis with splenic septic emboli associated with active infective endocarditis and anaerobic bacteremia complicated by ruptured spleen. A 62-year-old female patient was admitted because of fever and pain in the left upper abdomen and swelling and hematoma around the left brachiocephalic arteriovenous fistula. Transthoracic echocardiography revealed mobile hyperechoic mass (vegetation) on the anterior mitral valve. Abdominal ultrasound scan showed multiple hypoechoic lesions of the enlarged spleen, described as possible necroses or abscesses, and computed tomography showed low-density inhomogeneous lesions in the enlarged spleen with large perisplenic hematoma, with spleen rupture. Blood culture revealed anaerobic Gram-negative bacilli ( Bacteroides spp.), ampicillin resistant. This is the first report of splenic rupture associated with anaerobic bacteremia and splenic septic emboli in a uremic patient on chronic hemodialysis. Splenic septic emboli with abscess/infarction in hemodialysis patients are a rare disorder but could be a consequence of dialysis access site infection and might predispose to splenic rupture. Ultrasound scan of abdomen is fast, inexpensive and easy to perform. As mortality is high, early surgical intervention on vascular access is mandatory.