Infective Endocarditis: The European Viewpoint

Infective endocarditis: association between origin of causing bacteria and findings during oral infection screening

Background

Oral streptococci represent the causing microorganism for infective endocarditis (IE) in many patients. The impact of oral infections is questioned, and it has been suggested that bacteraemia due to daily routines may play a bigger part in the aetiology of IE. The aim of this study was to examine the association between oral health and infective endocarditis caused by oral bacteria in comparison with bacteria of other origin than the oral cavity.

Methods

A retrospective study was conducted at Haukeland University Hospital from 2006- 2015. All consecutive adult patients admitted to hospital for treatment of IE and subjected to an oral focus screening including orthopantomogram, were included. The clinical, radiological and laboratory characteristics of the patients, collected during oral infectious focus screening, were analysed. Patient survival was calculated using Kaplan–Meier and mortality rates were compared using Cox-regression.

Results

A total of 208 patients were included, 77% (n = 161) male patients and 23% (n = 47) female, mean age was 58 years. A total of 67 (32%) had IE caused by viridans streptococci. No statistically significant correlation could be found between signs of oral infection and IE caused by viridans streptococci. The overall mortality at 30 days was 4.3% (95% CI: 1.6–7.0). There was no statistical difference in mortality between IE caused by viridans streptococci or S. aureus (HRR = 1.16, 95% CI: 0.57–2.37, p = 0.680).

Conclusion

The study indicates that the association between origin of the IE causing bacteria and findings during oral infection screening might be uncertain and may suggest that the benefit of screening and elimination of oral infections in patients admitted with IE might be overestimated. However, the results should be interpreted with caution and further studies are needed before any definite conclusions can be drawn.

Infective Endocarditis in High-Income Countries

Infective endocarditis remains an illness that carries a significant burden to healthcare resources. In recent times, there has been a shift from Streptococcus sp. to Staphylococcus sp. as the primary organism of interest. This has significant consequences, given the virulence of Staphylococcus and its propensity to form a biofilm, rendering non-surgical therapy ineffective. In addition, antibiotic resistance has affected treatment of this organism. The cohorts at most risk for Staphylococcal endocarditis are elderly patients with multiple comorbidities. The innovation of transcatheter technologies alongside other cardiac interventions such as implantable devices has contributed to the increased risk attributable to this cohort. We examined the pathophysiology of infective endocarditis carefully. Inter alia, the determinants of Staphylococcus aureus virulence, interaction with host immunity, as well as the discovery and emergence of a potential vaccine, were investigated. Furthermore, the potential role of prophylactic antibiotics during dental procedures was also evaluated. As rates of transcatheter device implantation increase, endocarditis is expected to increase, especially in this high-risk group. A high level of suspicion is needed alongside early initiation of therapy and referral to the heart team to improve outcomes.

Double Valve Infective Endocarditis Complicated by Systemic Arterial Embolization

A 26-year-old male with a past medical history of intravenous opioid abuse was admitted with the diagnosis of double valve infective endocarditis and methicillin-resistant Staphylococcus aureus bacteremia. Imaging, excluding the head, was indicative of systemic arterial embolization, as abscesses had developed in the retroperitoneum and prostate. There was evidence of splenic infarct, and the presence of extensive pulmonary infiltrates indicative of showering septic foci from the heart. Antibiotic therapy was started and a transesophageal echocardiogram demonstrated mitral and tricuspid valve vegetations with a preserved ejection fraction. Fortunately, the valvular repair was successful and artificial valves were not needed. The patient had an uncomplicated postoperative course in the intensive care unit and was transferred back to the ward in stable condition. He remained on the ward for six weeks due to his unfunded status until his antibiotic course and physical rehabilitation were completed.

Staphylococcal Enterotoxins and Toxic Shock Syndrome Toxin-1 and Their Association among Bacteremic and Infective Endocarditis Patients in Egypt

Purpose

Infective endocarditis (IE) is a major complication in patients with bacteremia of Staphylococcus (S.) aureus infection. Our aim was to determine the association of the major Staphylococcal superantigens (SAgs), including Staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin-1 (TSST-1), among hospitalized patients diagnosed with bacteremia and those with IE.

Methods

This study was conducted on 88 patients; of these, 84 (95.5%) had two positive blood cultures. Eighteen out of the 84 patients (21.4%) were diagnosed based on the modified Duke criteria by a cardiologist to have IE. The recovered isolates were screened phenotypically using ELISA followed by molecular analysis of sea, seb, sec, sed, see, and tsst-1, the major SAg coding genes, and the obtained findings were statistically analyzed.

Results

Phenotypic screening for SE production of 26 selected Staphylococci (15 isolated from the IE patients (10 S. aureus and 5 coagulase negative staphylococci (CoNS)) and 11 from bacteremic patients (10 S. aureus and 1 CoNS)) using ELISA revealed that 12/26 (46%) isolates were SE producers. PCR analysis showed that 19 (73%) isolates were PCR positive for SAg genes with the highest prevalence of the sea gene (79%), followed by seb (63%) and tsst-1 (21%). The least frequent gene was sed (5.3%). Statistical correlations between bacteremic and IE isolates with respect to prevalence of SAgs showed no significant difference (P value = 0.139, effect size = 0.572) indicating no specific association between any of the detected SAgs and IE.

Conclusion

There is high prevalence of SEs among clinical isolates of Staphylococci recovered from patients suffering bacteremia and those with IE. No significant difference was found among Staphylococcal isolates recovered from patients with bacteremia or IE regarding both phenotypic and genotypic detection of the tested SAgs.

Imaging infective endocarditis: Adherence to a diagnostic flowchart and direct comparison of imaging techniques

BACKGROUND

Multimodality imaging is recommended to diagnose infective endocarditis. Value of additional imaging to echocardiography in patients selected by a previously proposed flowchart has not been evaluated.

METHODS

An observational single-center study was performed. Adult patients suspected of endocarditis/device infection were prospectively and consecutively enrolled from March 2016 to August 2017. Adherence to a diagnostic imaging-in-endocarditis-flowchart was evaluated in 176 patients. Imaging techniques were compared head-to-head in 46 patients receiving echocardiography (transthoracic plus transesophageal), multi-detector computed tomography angiography (MDCTA), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET/CT).

RESULTS

69% of patients (121/176) adhered to the flowchart. Sensitivity of echocardiography, MDCTA, FDG-PET/CT in patients without prosthesis was 71%, 57%, 29% (86% when combined), while specificity was 100%, 75%, 100%, respectively. Sensitivity in patients with prosthesis was 75%, 75%, 83%, respectively (100% when combined), while specificity was 86% for all three modalities. Echocardiography performed best in the assessment of vegetations, morphological valve abnormalities/dehiscence, septum defects, and fistula formation. MDCTA performed best in the assessment of abscesses and ventricular assist device infection. FDG-PET/CT performed best in the assessment of cardiac device infection, extracardiac infectious foci, and alternative diagnoses.

CONCLUSIONS

This study demonstrates that the evaluated imaging-in-endocarditis-flowchart is applicable in daily clinical practice. Echocardiography, MDCTA, and FDG-PET/CT provide relevant complementary diagnostic information, particularly in patients with intracardiac prosthetic material.

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.

Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) as independent predictors of outcome in infective endocarditis (IE)

Background

Early and accurate risk assessment is an important clinical demand in patients with infective endocarditis (IE). The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are independent predictors of prognosis in many infectious and cardiovascular diseases. Very limited studies have been conducted to evaluate the prognostic role of these markers in IE.

Results

We analyzed clinical, laboratory, and echocardiographic data and outcomes throughout the whole period of hospitalization for a total of 142 consecutive patients with definitive IE.

The overall in-hospital mortality was 21%. Major complications defined as central nervous system embolization, fulminant sepsis, acute heart failure, acute renal failure, and major artery embolization occurred in 38 (27%), 34 (24%), 32 (22.5%), 40 (28%), and 90 (63.4%) patients, respectively.

The NLR, total leucocyte count (TLC), neutrophil percentage, creatinine, and C-reactive protein (CRP) level obtained upon admission were significantly higher in the mortality group [p ≤ 0.001, p = 0.008, p = 0.001, p = 0.004, and p = 0.036, respectively].

A higher NLR was significantly associated with fulminant sepsis and major arterial embolization [p = 0.001 and p = 0.028, respectively].

The receiver operating characteristic (ROC) curve of the NLR for predicting in-hospital mortality showed that an NLR > 8.085 had a 60% sensitivity and an 84.8% specificity for an association with in-hospital mortality [area under the curve = 0.729, 95% confidence interval (CI) 0.616–0.841; p = 0.001]. The ROC curve of the NLR for predicting severe sepsis showed that an NLR > 5.035 had a 71.8% sensitivity and a 68.5% specificity for predicting severe sepsis [area under the curve 0.685, 95% CI 0.582–0.733; p = 0.001].

The PLR showed no significant association with in-hospital mortality or in-hospital complications.

Conclusion

A higher NLR, TLC, neutrophil percentage, creatinine level, and CRP level upon admission were associated with increased in-hospital mortality and morbidity in IE patients. Furthermore, a lower lymphocyte count/percentage and platelet count were strong indicators of in-hospital mortality among IE patients.

Calculation of the NLR directly from a CBC upon admission may assist in early risk stratification of patients with IE.

Prevention of infective endocarditis and bacterial resistance to antibiotics: A brief review

The purpose of this statement is to debate the recommendations of the American Heart Association (AHA) for the prevention of infective endocarditis through an antibiotic prophylaxis protocol and its relation with bacterial resistance to antibiotics. Since dental infections involve biofilms that include several bacterial species (Gram-negative and Gram-positive), it is essential, from the dental point of view, to consider the frequency, magnitude, and duration of bacteremia associated with active dental infections before applying antibiotic prophylaxis. The actual guidelines for antibiotic prophylaxis should be revised according to recent evidence of bacterial resistance. Amoxicillin/clavulanic acid and moxifloxacin should be considered due to their effectiveness against bacteria associated with oral, GU, and GI infections and the low rates of antibiotic resistance associated with these antibiotics, instead of the actual protocol, which includes amoxicillin (2 g) or clindamycin (600 mg) administered an hour before the dental procedures. The breaking point to test the antibiotic bacterial resistance (ABR) had a wide range in the different studies that were analyzed, which could explain the widely varied ABR percentages reported for the various antibiotics used for antibiotic prophylaxis.

Invasive Procedures Associated With the Development of Infective Endocarditis

BACKGROUND

Various invasive medical procedures might induce bacteremia and, hence, act as triggers for infective endocarditis. However, empirical data in humans on the potential dangers of invasive medical procedures in this regard are very sparse. Due to lack of sufficient data, it is currently debated whether the risk for endocarditis with medical procedures is substantial or rather negligible.

OBJECTIVES

The purpose of this nationwide case-crossover study was to quantify the excess risk for infective endocarditis in association with invasive medical and surgical procedures.

METHODS

The authors identified all adult patients treated for endocarditis in hospitals in Sweden between January 1, 1998, and December 31, 2011. The authors applied a case-crossover design and compared the occurrence of invasive medical procedures 12 weeks before endocarditis with a corresponding 12-week time period exactly 1 year earlier. The authors considered all invasive nondental medical procedures except for those that are likely to be undertaken due to endocarditis or sepsis or due to infections that could possibly lead to endocarditis.

RESULTS

The authors identified 7,013 cases of infective endocarditis during the study period. Among others, several cardiovascular procedures, especially coronary artery bypass grafting; procedures of the skin and management of wounds; transfusion; dialysis; bone marrow puncture; and some endoscopies, particularly bronchoscopy, were strongly associated with an increased risk for infective endocarditis.

CONCLUSIONS

This study suggests that several invasive nondental medical procedures are associated with a markedly increased risk for infective endocarditis.

[Infectious endocarditis: Experience of a cardiology department at Oran university hospital]

INTRODUCTION

Infectious endocarditis (IE) is a serious disease that has continued to evolve in diagnostic and therapeutic terms.

AIM

To analyze the diagnostic and out come profile.

METHODS

We collected 57 (IE) cases with a definite diagnosis according to the modified Duke criteria. Patients were admitted consecutively to the Cardiology Department of the Oran university hospital from January 2011 to June 2017. Among the variables studied: clinical data, paraclinic data, therapeutic management and hospital outcome.

RESULTS

The mean age was 40.5±15 years (extreme 16-67 years), with a male predominance (sex-ratio=1.5). This was a native valve IE in 70% of cases, on valve prosthesis in 15.5% of patients, on congenital heart disease in 2% and on pacemaker probe in 4% of cases. The entrance door was dominated by oral origin. Blood cultures were positive only in 51% of cases. The most commonly implicated organism in staphylococci in 22.6%, streptococcus in 18.9% and brucellosis in 3.8%. Ultrasound data revealed vegetation (83%), cardiac abscess (19%), valvular perforation (15.1%) and prosthesis disintegration (7.5%). Complications were mainly neurological complications (27%) and hemodynamics (26%). Cardiac surgery occurred in 29% of patients. Hospital mortality was 26%, predictive factors were staphylococcal AI (P<0.001), cardiac insufficiency (P<0.001) and neurological complications (P=0.04).

CONCLUSION

Infectious endocarditis is a serious disease in the absence of surgery. The diagnosis is based on echocardiography in the first place and blood cultures. The population is often young revealing the EI by complications; its prevention is the best way to improve its prognosis.

Streptococcus mutans activates the AIM2, NLRP3 and NLRC4 inflammasomes in human THP-1 macrophages

Streptococcus mutans (S. mutans), a major aetiologic agent of dental caries, is involved in systemic diseases, such as bacterial endocarditis, if it enters the bloodstream through temporary bacteraemia. Interleukin (IL)-1β, a proinflammatory cytokine, is related to the host defences against pathogens, and its synthesis, maturation, and secretion are tightly regulated by the activation of the inflammasome, an inflammatory signalling complex. This study examined the signalling mechanism of IL-1β secretion and the inflammasome pathway induced by S. mutans to explain the molecular mechanism through which systemic infection by oral streptococci can occur. After infection of THP-1 cells with S. mutans, the expression of inflammasome components was detected using various methods. S. mutans induced IL-1β secretion via caspase-1 activation, and S. mutans-induced IL-1β secretion required absent in melanoma (AIM2), NLR family pyrin domain-containing 3 (NLRP3) and NLR family CARD domain-containing 4 (NLRC4) inflammasome activation. In particular, the S. mutans-induced NLRP3 inflammasome was mediated by adenosine triphosphate (ATP) release, potassium depletion and lysosomal damage. Our study provides novel insight into the innate immune response against S. mutans infection.

Streptococcus mutans triggers an early-stage immune response via a chain of events that leads to the activation of immune component, interleukin-1β. A group of academics from Korea’s Pusan National University, led by Jin Chung, tested the response of human immune cell cultures to infection with S. mutans—a common oral bacteria that can cause systemic disease if it enters the bloodstream. The group found that S. mutans infection leads to the activation of protein signaling complexes known as inflammasomes, which in turn activate an enzyme known as caspase-1. Caspase-1 then activates interleukin-1β, a pro-inflammatory molecule that forms part of a host’s defenses against pathogens. The team also identified that ATP release, ion depletion, and integrity of intracellular enzyme containers, also impacted inflammasome activation. This study offers insights into the immune response against S. mutans and may inform future investigations into systematic oral bacteria infections.

Association between route of illicit drug administration and hospitalizations for infective endocarditis

Objective

This study examined the association between the route of drug administration and being hospitalized for infective endocarditis among 4817 treatment-seeking illicit drug users in Finland.

Methods

Cox regression models were used to examine the association between the route of drug administration and infective endocarditis hospitalization, adjusted for age, gender, and homelessness. Cases of infective endocarditis as a primary/main diagnosis were tracked using the 10th version of the International Classification of Disease code I33.

Results

In all, 47 persons had a primary diagnosis of infective endocarditis. These 47 persons contributed a total of 95 hospitalizations and their total length of hospital stay was 1393 days. There was a statistically significant difference in hospitalizations between injectors and non-injectors (Log-Rank test p = 0.018). Univariate Cox model showed that injectors had higher hazard or risk for infective endocarditis hospitalization compared to non-injectors (hazard ratio: 2.04, 95% confidence interval: 1.12-3.73, p = 0.020). After adjusting for age, gender, and homelessness in the multivariate model, the elevated hazard among injectors compared to non-injectors remained statistically significant with adjusted hazard ratio of 2.12 (95% confidence interval: 1.11-4.07, p = 0.024).

Conclusion

The study findings suggested a need to boost harm reduction measures targeting high-risk injecting and other health behaviors among injecting drug users in order to reduce their hospitalizations for infective endocarditis.

Staphylococcal versus Streptococcal infective endocarditis in a tertiary hospital in Belgium: epidemiology, clinical characteristics and outcome

Infective endocarditis (IE) is a rare but serious illness associated with a high mortality. Staphylococcus spp and Streptococcus spp are the most frequent causative pathogens. In this study, we compared the epidemiology, clinical characteristics and outcomes of patients with Staphylococcal and Streptococcal IE in a tertiary hospital. Using our institutional database 'Medical Explorer', we collected all cases of IE retrospectively between January 2005 and December 2010 at the Cliniques Universitaires Saint Luc and then focused on Staphylococcal and Streptococcal IE. Of the 212 patients with IE included in our study, Staphylococcus spp accounted for 35.9% (76/212) of the cases, Streptococcus spp for 35.4% (75/212) and the remainder 18% (61/212) of cases were caused by other pathogens. Negative blood culture IE accounted for 10.4% of all cases. Demographic and clinical characteristics such as age, gender, fever, presence of a heart murmur, heart failure, nature of the affected valve, location of the endocarditis, duration of antibiotics, length of stay and complication were not different when comparing Staphylococcal and Streptococcal IE; only mortality differed. The mortality rate was 21.4 and 6.6% (p = 0.02) for Staphylococcal and Streptococcal IE, respectively. In the multivariate analysis, age >60 years, Staphylococcal IE, presence of complications and absence of surgery were independent risk factors for mortality.

Evaluation of epidemiological, clinical, and microbiological features of definite infective endocarditis

Background: Infective endocarditis (IE) is a microbial infection of heart valves and its endothelial lining which is considered as a life-threatening disorder. This study evaluated the epidemiological, clinical, and microbiological features of IE at the Cardiovascular Research Center in Yazd, Iran.

Methods: The cross-sectional study was conducted on 20 patients diagnosed with definite IE on the basis of Duke’s criteria hospitalized for one year in the Cardiovascular Research Center in Yazd, Iran, from January 2015 to December 2015. Demographic information, clinical, laboratory, and microbiological findings, and also trans-esophageal echocardiography (TEE) of each patient were recorded and assessed. The collected data were analyzed using SPSS 16.

Results: The mean age of the patients under study was 45±16 years with most of the afflicted patients (60%) being male. Most cases (70%) of IE were observed in the warm seasons (spring and summer). The most common clinical sign (80%) was fever. TEE was positive for all (100%) patients, and vegetation was seen in all patients. The nosocomial mortality rate was zero. However, 14 (70%) patients underwent surgical treatment. The valves afflicted with IE were: the mitral valve (40%), the aortic valve (35%), and the tricuspid valve (25%), respectively. 4 patients (20%) had a positive history of IE. Blood culture test was positive only in 1 case and the isolated microorganism belonged to the viridans group streptococci.

Conclusion: Despite the one-year high prevalence of IE in this study, the nosocomial mortality rate was not high and was reported to be nil under surgical and antimicrobial therapy.

The increasing incidence of infective endocarditis in Denmark, 1994-2011

BACKGROUND

Little updated population-based evidence exists of temporal trends in infective endocarditis (IE).

METHODS

For the 1994-2011 period, we used Danish nationwide registries to identify cases with first-time IE and to estimate the population size. We calculated the incidence rate of IE in 3-year intervals. To evaluate time trends in incidence, we used the 1994-1996 period as reference and computed incidence ratios and 95% confidence intervals (CI) as the incidence in each of the subsequent 3-year intervals divided by the incidence in the reference period.

RESULTS

We identified 5486 incident IE patients (65% men) and the mean age at diagnosis was 63years. Men tended to be younger at diagnosis than women; 62years vs. 65years. Mean age at IE diagnosis steadily increased from 57years in 1994-1996 to 65years in 2009-2011. The IE incidence rate increased from 3.93 per 100,000 person-years in 1994-1996 to 7.55 per 100,000 person-years in 2009-2011, corresponding to an incidence ratio of 1.92 (95% CI: 1.74-2.12). The increase in incidence over time was more pronounced in men (2.28, 95% CI: 2.02-2.59) than in women (1.39, 95% CI: 1.18-1.64). We observed no increase in incidence over time for subjects younger than 50years, whereas the incidence increased substantially over time for elderly patients, with the highest incidence ratio of 3.38 (95% CI: 2.55-4.52) for patients more than 80years at IE onset.

CONCLUSION

The incidence of IE increased over time particularly among men and for the older age groups.

The causative agents in infective endocarditis: a systematic review comprising 33,214 cases

Infective endocarditis (IE) incidence remains high with considerable fatality rates; guidelines for prophylaxis against IE are currently under review in some settings which highlights the importance of maintaining up-to-date epidemiological estimates about the most common microbial causes. The objective of this systematic review, following PRISMA guidelines, was to identify the most common microbial causes of IE in recent years. Medline was searched from January 1, 2003 to March 31, 2013 for all articles containing the term "infective endocarditis". All relevant studies reporting diagnostic results were included. Special patient subpopulations were assessed separately. A total of 105 studies were included, from 36 countries, with available data on a total of 33,214 cases. Staphylococcus aureus was found to be the most common microorganism, being the most frequent in 54.3 % of studies (N = 57) (and in 55.4 % of studies using Duke's criteria for diagnosis [N = 51]). Viridans group streptococci (VGS), coagulase-negative staphylococci (CoNS), Enterococcus spp and Streptococcus bovis were among the most common causes. S. aureus was the most common pathogen in almost all population subgroups; however, this was not the case in patients with implantable devices, prosthetic valves, or immunocompromised non-HIV, as well as in the sub-group from Asia, emphasizing that a global one-size-fits-all approach to the management of suspected IE is not appropriate. This review provides an evidence-based map of the most common causative agents of IE, highlighting S. aureus as the leading cause in the 21st century. The changing epidemiology of IE in some patient sub-groups in the last decade and the very high number of microbiologically undiagnosed cases (26.6 %) suggest the need to revisit IE prophylaxis and diagnostic strategies.

Advantages and Limitations of Direct PCR Amplification of Bacterial 16S-rDNA from Resected Heart Tissue or Swabs Followed by Direct Sequencing for Diagnosing Infective Endocarditis: A Retrospective Analysis in the Routine Clinical Setting

Infective endocarditis (IE) is a life-threatening disease that is associated with high morbidity and mortality. Its long-term prognosis strongly depends on a timely and optimized antibiotic treatment. Therefore, identification of the causative pathogen is crucial and currently based on blood cultures followed by characterization and susceptibility testing of the isolate. However, antibiotic treatment starting prior to blood sampling or IE caused by fastidious or intracellular microorganisms may cause negative culture results. Here we investigate the additional diagnostic value of broad-range PCR in combination with direct sequencing on resected heart tissue or swabs in patients with tissue or swab culture-negative IE in a routine clinical setting. Sensitivity, specificity, and positive and negative predictive values of broad-range PCR from diagnostic material in our patients were 33.3%, 76.9%, 90.9%, and 14.3%, respectively. We identified a total of 20 patients (21.5%) with tissue or culture-negative IE who profited by the additional application of broad-range PCR. We conclude that broad-range PCR on resected heart tissue or swabs is an important complementary diagnostic approach. It should be seen as an indispensable new tool for both the therapeutic and diagnostic management of culture-negative IE and we thus propose its possible inclusion in Duke's diagnostic classification scheme.

Infective endocarditis

Infective endocarditis occurs worldwide, and is defined by infection of a native or prosthetic heart valve, the endocardial surface, or an indwelling cardiac device. The causes and epidemiology of the disease have evolved in recent decades with a doubling of the average patient age and an increased prevalence in patients with indwelling cardiac devices. The microbiology of the disease has also changed, and staphylococci, most often associated with health-care contact and invasive procedures, have overtaken streptococci as the most common cause of the disease. Although novel diagnostic and therapeutic strategies have emerged, 1 year mortality has not improved and remains at 30%, which is worse than for many cancers. Logistical barriers and an absence of randomised trials hinder clinical management, and longstanding controversies such as use of antibiotic prophylaxis remain unresolved. In this Seminar, we discuss clinical practice, controversies, and strategies needed to target this potentially devastating disease.

Homograft Aortic Root Replacement with Saphenous Vein Graft Hemi-Cabrol for Prosthetic Aortic Valve Endocarditis

A 44-year-old female presented with prosthetic valve endocarditis with periannular abscess involving the left coronary ostium. We describe cryopreserved aortic homograft root replacement with hemi-Cabrol reimplantation of the left coronary ostium using the long saphenous vein.

Association between hematologic parameters and in-hospital mortality in patients with infective endocarditis

Early and accurate risk prediction is an important clinical demand in patients with infective endocarditis (IE). The platelet-to-lymphocyte ratio (PLR) is an independent predictor of worse prognosis in various cardiovascular diseases. The aim of this study was to determine the value of PLR in the prediction of in-hospital mortality among IE patients. We retrospectively analyzed the clinical, laboratory, and echocardiographic data of 59 adult patients with definite IE and in 40 adult controls. In-hospital mortality occurred in 16 (27%) patients. Vegetation size, levels of high-sensitive C-reactive protein and procalcitonin, neutrophil-to-lymphocyte ratio, and PLR were significantly higher in the in-hospital-mortality-positive group than in the in-hospital-mortality-negative group (p = 0.004, p = 0.009, p = 0.030, p = 0.001, and p = 0.008, respectively). Lymphocyte count was, however, significantly lower in the in-hospital-mortality-positive group (p = 0.004). In the receiver-operating characteristic analysis, PLRs over 191.01 predicted in-hospital mortality with 56.3% sensitivity and 81.4% specificity [area under the curve 0.725, 95% confidence interval (CI) 0.594-0.833; p = 0.0027]. In the multivariate analysis, PLR was found to be an independent predictor of in-hospital mortality in patients with IE (odds ratio 1.022, 95% CI 1.003-1.042; p = 0.021). In conclusion, higher PLR may predict in-hospital mortality in patients with IE.

Epidemiology of infective endocarditis in a large Belgian non-referral hospital

OBJECTIVES

Guidelines for diagnosis of infective endocarditis are largely based upon epidemiological studies in referral hospitals. Referral bias, however, might impair the validity of guidelines in non-referral hospitals. Recent studies in non-referral care centres on infective endocarditis are sparse. We conducted a retrospective epidemiological study on infective endocarditis in a large non-referral hospital in a Belgian city (Kortrijk).

METHODS

The medical record system was searched for all cases tagged with a putative diagnosis of infective endocarditis in the period 2003-2010. The cases that fulfilled the modified Duke criteria for probable or definite infective endocarditis were included.

RESULTS

Compared to referral centres, an older population with infective endocarditis, and fewer predisposing cardiac factors and catheter-related infective endocarditis is seen in our population. Our patients have fewer prosthetic valve endocarditis as well as fewer staphylococcal endocarditis. Our patients undergo less surgery, although mortality rate seems to be highly comparable with referral centres, with nosocomial infective endocarditis as an independent predictor of mortality.

CONCLUSION

The present study suggests that characteristics of infective endocarditis as well as associative factors might differ among non-referral hospitals and referral hospitals.

Association between HACEK bacteraemia and endocarditis

We retrospectively examined medical records of 87 patients with bacteraemia caused by members of the HACEK group (Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aphrophilus, Aggregatibacter paraphrophilus, Cardiobacterium spp., Eikenella corrodens and Kingella spp.) to determine whether endocarditis was present, as defined by the Duke criteria. The overall positive predictive value (PPV) of HACEK bacteraemia for endocarditis was 60 %. The PPV varied with different HACEK species from 0 % (E. corrodens) to 100 % (A. actinomycetemcomitans).

Retrospective studies on pediatric infective endocarditis over 40 years in a mid-west area of China

OBJECTIVE

We have evaluated 106 pediatric cases of infective endocarditis (IE) to elucidate clinical manifestations and pathogenic microorganism profiling of IE in China.

METHODS

Clinical features, complications, pathogenic microorganisms, diagnosis and treatment of pediatric IE were reviewed in two groups of patients with IE from the different periods of time (group A, 34 cases obtained in the period from 2000 to 2011 and group B, 72 cases obtained in the period from 1964 to 1999).

RESULTS

A total of 106 pediatric patients with a definite diagnosis of IE based on the modified Duke criteria were enrolled and evaluated in this study. By comparing two groups of patients from different time periods, we found that the incidence of rheumatic heart disease was significantly reduced (from 19.4 to 5.9%), whereas congenital heart disease-associated IE had a tendency to increase (from 55.6 to 79.4%). Staphylococcus aureus was detected as the most common pathogenic microorganism, and its involvement tended to increase (from 32.0 to 58.5%), whereas the percentage of infections caused by Streptococcus viridans (8.0%) had not changed. It was interesting to note that the rate of vegetations detected was increased from 50.0 to 67.6% and the incidence of right-sided IE was also increased (from 35.0 to 60.9%). The most common valves involved in recent cases were tricuspid valves (increase from 30.0 to 47.8%), while mitral valve infection was reduced (from 60.0 to 39.1%). Penicillin was still the most commonly used antibiotic for the treatment of IE; the combination of penicillin plus cephalosporin has been recommended more and more recently.

CONCLUSIONS

Comparing pediatric IE patients during the past 40 years, we found that the role of rheumatic heart disease as a predisposing factor is diminishing. Pediatric IE is still predominantly caused by staphylococci. The most commonly involved valves are tricuspid valves instead of mitral valves. Gram-positive bacteria showed an increased resistance to penicillin when used alone, and the use of combination treatment with antibiotics is increasing in the area.

Is there a need for bacterial endocarditis prophylaxis in patients undergoing urological procedures?

Heart valve repair or replacement is a serious problem.The focused update on infective endocarditis of American College of Cardiology/American Heart Association 2008 (ACC/AHA guidelines) and Guidelines on the prevention, diagnosis, and treatment of infective endocarditis (new version 2009) of the European Society of Cardiology (ESC guidelines) describe prophylaxis against infective endocarditis as not recommended for urinary tract procedures in the absence of active infection. A statistical association has been recently shown between urological procedures and the development of infective endocarditis. New evidences concerning infective endocarditis due to Actinobaculum schaalii, Neisseria gonorrhoeae, Streptococcus agalactiae, Enterococcus faecalis, Pseudomonas aeruginosa, Aerococci and Staphylococcus aureus, and new findings indicate there is a need for bacterial endocarditis prophylaxis in patients undergoing urological procedures especially in elderly patients and in cancer and immunocompromised patients, to avoid serious consequences.

Is there a need for bacterial endocarditis prophylaxis in patients undergoing gastrointestinal endoscopy?

Heart valve repair or replacement is a serious problem. Patients can benefit from an open dialogue between both cardiologists and gastroenterologists for the optimal effective patients care. The focused update on infective endocarditis of the American College of Cardiology/American Heart Association 2008 (ACC/AHA guidelines) and guidelines on the prevention, diagnosis, and treatment of infective endocarditis (new version 2009) of the European Society of Cardiology (ESC guidelines) describe prophylaxis against infective endocarditis (IE) as not recommended for gastroscopy and colonoscopy in the absence of active infection but increasing evidence suggests that the role of IE antibiotic prophylaxis remains a dark side of the cardio-oncology prevention. New evidences concerning infective endocarditis due to Streptococcus bovis, Streptococcus agalactiae, Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, and new findings indicate that there is a need for bacterial endocarditis prophylaxis in patients undergoing gastrointestinal endoscopy especially in elderly patients and in cancer and immunocompromised patients, to avoid serious consequences.

Maternal understanding of infective endocarditis after hospitalization: assessing the knowledge of mothers of children with congenital heart disease and the practical implications

This study aimed to examine the knowledge of mothers of children with congenital heart disease as well as the association of cardiological factors and maternal characteristics with maternal understanding. Mothers of 135 children (≤2 years old) were interviewed to assess maternal knowledge of infective endocarditis (IE) using the Hannover Inventory of Parental Knowledge of Congenital Heart Disease. Two subscales, endocarditis and risk factors, were used. Cardiological data as well as maternal characteristics were collected. Two-thirds of the mothers achieved only low scores, answering 0-20 % of the questions correctly (endocarditis = 64.4 %; risk factors = 71.1 %). Mothers with higher education recalled the correct definition of IE (P = 0.001) and the importance of dental hygiene (P = 0.004) more often. Mothers with only one child were more likely to know the most typical symptom (P = 0.007). The severity of the heart disease and the requirement of endocarditis prophylaxis did not influence maternal understanding. Yet, mothers assessing the heart disease as severe showed better knowledge (typical symptom P = 0.021; importance of dental hygiene P = 0.007). If mothers learned the diagnosis before their child's birth, they remembered relevant information more often. Mothers receiving information by the medical staff and from the Internet showed better knowledge (definition P = 0.014; importance of dental hygiene P = 0.001). Due to low levels of knowledge, more efforts must be put into the education of mothers. Educational programs should take maternal characteristics into account, providing written material and thereby keeping the instruction of lower-educated persons in mind. Furthermore, education should be focused on mothers of children requiring IE prophylaxis.

Bugs, hosts and ICU environment: countering pan-resistance in nosocomial microbiota and treating bacterial infections in the critical care setting

ICUs are areas where resistance problems are the largest, and these constitute a major problem for the intensivist's clinical practice. Main resistance phenotypes among nosocomial microbiota are (i) vancomycin-resistance/heteroresistance and tolerance in grampositives (MRSA, enterococci) and (ii) efflux pumps/enzymatic resistance mechanisms (ESBLs, AmpC, metallo-betalactamases) in gramnegatives. These phenotypes are found at different rates in pathogens causing respiratory (nosocomial pneumonia/ventilator-associated pneumonia), bloodstream (primary bacteremia/catheter-associated bacteremia), urinary, intraabdominal and surgical wound infections and endocarditis in the ICU. New antibiotics are available to overcome non-susceptibility in grampositives; however, accumulation of resistance traits in gramnegatives has led to multidrug resistance, a worrisome problem nowadays. This article reviews microorganism/infection risk factors for multidrug resistance, suggesting adequate empirical treatments. Drugs, patient and environmental factors all play a role in the decision to prescribe/recommend antibiotic regimens in the specific ICU patient, implying that intensivists should be familiar with available drugs, environmental epidemiology and patient factors.

Multiple myeloma complicated with pseudomonas endocarditis

Patients diagnosed with multiple myeloma are more susceptible to infections which are the major causes of morbidity and mortality associated to this disease. The main infectious agents involved are Gram-positive bacteria. However, after chemotherapy an increase in the incidence of Gram-negative strains is observed. These bacteria are also responsible for most cases of urinary tract infections. Here is reported a rare case in a 73-year-old man with multiple myeloma who developed endocarditis due to pseudomonas.

Reappraisal of a single-centre policy on the contemporary surgical management of active infective endocarditis

OBJECTIVES

We studied a contemporary cohort of adult patients treated surgically for infective endocarditis (IE) in order to evaluate the surgical approach and predictors of outcomes, in relation to the intercurrent adaptation of the 2006 ACC/AHA guidelines.

METHODS

One hundred and eighty-six consecutive patients operated on for active IE from August 1999 to September 2012 were reviewed retrospectively. Clinical presentation, surgical management and outcomes in the two study periods before and after January 2007 were compared (Period 1: n = 95 and Period 2: n = 91).

RESULTS

The mean (SD) follow-up was 4.3 (3.8) years and was 99.5% complete. Patients in Period 2 had more frequently associated coronary artery disease (31 vs 18%, P = 0.06), while the microbiology revealed more Staphylococcus species (43 vs 26%, P = 0.02), predominantly Staphylococcus aureus (31 vs 19%; P = 0.07), and less culture-negative cases (7 vs 17%; P = 0.05). The median delay between diagnosis and surgery was 7 days in Period 2 compared with 14 days in Period 1 (P = 0.001). Surgery in Period 2 included more root replacements for aortic valve endocarditis (11 vs 2%; P = 0.02) and mitral valve repairs (18 vs 5%; P = 0.01), while the use of homografts for aortic valve endocarditis was almost abandoned (1 vs 15%; P = 0.001). Hospital mortality was 13% and did not change significantly over both periods (P = 0.66). The independent predictors of hospital mortality were age (P = 0.03), female gender (P = 0.02), previous cardiac surgery (P = 0.02), preoperative serum creatinine level >2 mg/dl (P = 0.05), S. aureus infection (P = 0.02), emergent or salvage operation (P = 0.001) and concomitant coronary artery bypass grafting (P = 0.03). The 1-, 3-, 5- and 10-year survival were 84, 72, 64 and 57%, respectively. Late survival was negatively influenced by S. aureus endocarditis (P < 0.001) and peripheral vascular disease (P = 0.03), whereas associated coronary artery disease (P = 0.07) had a strong impact.

CONCLUSIONS

Adaptation of the 2006 ACC/AHA guidelines in the contemporary management of IE led to a shorter interval between diagnosis and surgery. Despite a more extensive and earlier operative approach, IE caused by S. aureus still remains a major determinant of early and late outcomes.

[Central nervous system embolism in the course of infective endocarditis]

Despite the progress made in diagnosis and treatment of heart valve diseases, the incidence of infective endocarditis (IE) remains constant. It is still associated with high mortality and high rate of embolic complications, including most dangerous one, i.e. stroke. It has a significant impact on further treatment and qualifications for cardiac surgery. In this paper, the authors discuss the epidemiology, mechanisms of stroke and its impact on the qualifications for cardiac surgery. The authors discuss the problem of clinically silent central nervous system embolism in the course of IE and the usefulness of neuroimaging and markers of central nervous system damage in diagnosis of cerebral embolism.

A rabbit model of right-sided Staphylococcus aureus endocarditis created with echocardiographic guidance

Background

The most widely used experimental models of infective endocarditis (IE) are the rabbit and rat models, in which cardiac valve lesions are induced by a polyethylene catheter introduced into the left ventricle through the aortic valve. Our study was designed to create a rabbit model of IE right-sided with echocardiographic guidance.

Methods

Thirty rabbits underwent both catheterization and inoculation (group A). These were divided into three subgroups of ten based on the time of catheter removal (immediately, after 24 h, and after death or moribundity for groups, A₁, A₂, and A₃, respectively). Ten inoculated-only and ten catheterized-only rabbits served as controls. A catheter system consisted of a polyethylene catheter and a guide wire inside it. This system was passed through the rabbits’ tricuspid valves under echocardiographic guidance to damage them. The ratio of left ventricle to right ventricle (LV/RV) was measured in a four-chamber view before catheterization and at the time of death or moribundity. The peak velocity of tricuspid regurgitation (V_TR) was measured in a four-chamber view at the time of catheterization and at the time of death or moribundity. Staphylococcus aureus (ATCC 29213) inoculation was performed 24 h after right heart catheterization to produce IE.

Results

IE was confirmed in 28 of 30 rabbits by macroscopic and histologic examination of tricuspid valves, blood cultures, and bacterial count in cardiac vegetations. Cardiac vegetations were confirmed in 25 of 28 IE rabbits by echocardiography. Enlargement of right ventricle dimension with a significantly decreased LV/RV ratio was confirmed in all IE rabbits at the time of death or moribundity than at the initial state (1.11 ± 0.35 vs. 1.95 ± 0.39, P < 0.01; 1.21 ± 0.34 vs. 1.98 ± 0.35, P < 0.01; 1.04 ± 0.31 vs. 2.00 ± 0.41, P < 0.01 for groups A₁, A₂, and A₃, respectively). V_TR was significantly higher in all the IE rabbits at the time of death or moribundity than at the time of catheterization (1.89 ± 0.46 vs 0.76 ± 0.45, P < 0.01; 2.04 ± 0.73 vs 0.68 ± 0.66, P < 0.01; 2.24 ± 0.51 vs 0.87 ± 0.55, P < 0.01 for group A₁, A₂ and A₃, respectively).

Conclusion

The models described herein closely reproduced the pathogenesis and pathophysiology of right heart catheter-induced endocarditis in humans. Echocardiographic guidance is helpful in the process of right heart catheterization. Some echocardiographic parameters, such as V_TR and the LV/RV ratio could be used to assess the success or failure of the IE models.

Identification and evaluation of a novel peptide binding to the cell surface of Staphylococcus aureus

Identification of short peptides that serve as specific ligands to biological materials such as microbial cell surfaces has major implications in better understanding the molecular recognition of cell surfaces. In this study we screened a commercially available random phage-display library against Staphylococcus aureus cells and identified peptides specifically binding to the bacteria. A synthetic peptide (SA5-1) representing the consensus sequence (VPHNPGLISLQG) of the bacteria-binding peptide was evaluated for its binding potential against S. aureus. Dot-blot, immunoblot assay and ELISA results revealed the SA5-1 peptide to be highly specific to S. aureus. The SA5-1 peptide binding was optimal between pH 6.0 and 8.0. Nanogold Transmission Electron Microscopy demonstrated that the SA5-1 binds to the outer membrane surface of S. aureus. Diagnostic potential of the SA5-1 peptide was evaluated in human platelet samples spiked with S. aureus and specific detection of the bacteria by biotinylated-SA5-1 and streptavidin-conjugated fluorescent quantum dots. Fluorometry results indicated that the peptide was able to detect ∼100 organisms per ml in a spiked biological sample providing a proof-of-concept towards potential of this peptide as a S. aureus diagnostic tool that can be of use in different detection platforms.

[Infective endocarditis in the XXI century: epidemiological, therapeutic, and prognosis changes]

Infective endocarditis (IE) is an uncommon and severe disease. Nowadays, in developed countries, IE patients are older, usually have a degenerative heart valve disease, and up to 30% acquire this infection within the health care system. In consequence, staphylococci species are the most frequently isolated microorganisms. Antimicrobial treatment for IE has significantly changed over the last decades. In IE episodes due to Staphylococcus aureus, cloxacillin-resistance makes antimicrobial election more difficult. Other microorganisms, such as enterococci and some species of streptococci, show high rates of resistance to antimicrobial agents established in guidelines. Despite improvements in the diagnosis, and medical and surgical treatment of IE, this disease continues to be associated with high rates of in-hospital mortality. At present, due to epidemiological changes, antimicrobial prophylaxis can avoid few cases of IE. Prevention of nosocomial bacteremia, an early diagnosis of IE, prompt identification of IE patients at a higher risk of mortality, and a multidisciplinary approach of this disease could be valid strategies in order to improve the outcome of these patients.