Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group

Management of pregnancy in patients with congenital heart disease

Congenital heart diseases are the most common birth defects in humans, affecting approximately 0.8% of all live births. In the past, many of the more severe defects resulted in profound disability and death during childhood, and adult survival was exceptional. The past 4 decades have seen dramatic improvements in the survival and quality of life of patients with the more severe defects. As a result of these improvements, the challenges of caring for adults with congenital heart disease are only now being realized. Most women with congenital heart disease are now expected to reach childbearing age and maternal cardiac disease is the major cause of maternal morbidity and mortality. As such, appropriate pre-pregnancy counseling and management during pregnancy are fundamental components of the care of these patients. This article describes the circulatory changes that occur during normal pregnancy and delivery, addresses the risks posed during pregnancy by specific congenital lesions, and reviews the current data on pregnancy outcomes in patients with individual congenital defects.

Algorithm for the management of antibiotic prophylaxis in onychocryptosis surgery

BACKGROUND

Antibiotic prophylaxis in nail surgery is not clearly established, and there is scant scientific evidence regarding the need for its use in preventing surgical site infection, hematogenous total joint infection, and infective endocarditis.

OBJECTIVES

To propose an algorithm based on the evidence for the management of antibiotic prophylaxis in onychocryptosis surgery.

METHODS

A literature review was performed in Medline, Pubmed, Cochrane database and Scopus and recent prospective studies were examined. The most-current authoritative guidelines together with new classification system of the pathology have been taken into account.

RESULTS

In non-risk patients with onychocryptosis stage II or III phenol technique can be used without the need for antibiotics. In stages IV and V, specific antibiotic treatment should be administered before surgery together with partial ablation of nail until the infection is resolved and the process remits to stage II or III. In the case of long-developing onychocryptosis, osteomyelitis should be ruled out, and specific antibiotic treatment besides the preoperative dose should be administered. In high-risk cardiac patients with infective onychocryptosis, the need for prophylaxis for bacterial endocarditis should be considered.

CONCLUSION

Current evidence does not support the use of preoperative antibiotic prophylaxis in onychocrytosis surgery except in special patients with infective onychocryptosis.

Enterococcus faecalis endocarditis severity in rabbits is reduced by IgG Fabs interfering with aggregation substance

Background

Enterococcus faecalis is a significant cause of infective endocarditis, an infection of the heart endothelium leading to vegetation formation (microbes, fibrin, platelets, and host cells attached to underlying endothelial tissue). Our previous research determined that enterococcal aggregation substance (AS) is an important virulence factor in causation of endocarditis, although endocarditis may occur in the absence of AS production. Production of AS by E. faecalis causes the organism to form aggregates through AS binding to enterococcal binding substance. In this study, we assessed the ability of IgGs and IgG Fabs against AS to provide protection against AS⁺E. faecalis endocarditis.

Methodology/Principal Findings

When challenged with AS⁺E. faecalis, 10 rabbits actively immunized against AS⁺E. faecalis developed more significant vegetations than 9 animals immunized against AS⁻E. faecalis, and 9/10 succumbed compared to 2/9 (p<0.005), suggesting enhanced aggregation by IgG contributes significantly to disease. IgG antibodies against AS also enhanced enterococcal aggregation as tested in vitro. In contrast, Fab fragments of IgG from rabbits immunized against purified AS, when passively administered to rabbits (6/group) immediately before challenge with AS⁺E. faecalis, reduced total vegetation (endocarditis lesion) microbial counts (7.9×10⁶ versus 2.0×10⁵, p = 0.02) and size (40 mg versus 10, p = 0.05). In vitro, the Fabs prevented enterococcal aggregation.

Conclusions/Significance

The data confirm the role of AS in infective endocarditis formation and suggest that use of Fabs against AS will provide partial protection from AS⁺E. faecalis illness.

Oral chronic graft-versus-host disease: report from the International Consensus Conference on clinical practice in cGVHD

Chronic graft-versus-host disease (cGVHD) is a multi-organ disease that occurs post-hematopoietic stem cell transplantation, with the mouth being one of the most frequently affected organs. In 2009, the German-Austrian-Swiss working party on bone marrow and blood stem cell transplantation held a consensus conference to define clinical management of cGVHD. The consensus conference aimed to summarize the literature on diagnosis and topical treatment options for oral cGVHD and to provide recommendations for clinical practice, including routine dental and oral care as well as monitoring for secondary malignancies and bisphophonate-induced osteonecrosis of the jaw.

Vascular haemostasis

SUMMARY

While the majority of this session will deal with selected inherited vascular abnormalities that may manifest as a haemorrhagic disorder, the initial discussion by Dr Key will focus on the interplay between the vessel wall and components of the coagulation system, with a focus on haemophilia A and B. Although it is generally accepted that physiological haemostasis is triggered by contact of blood with tissue factor (TF), there remains some controversy regarding the cellular origin of TF in vivo. In addition, the initiation and propagation of thrombin generation are highly dependent on the balance of pro- and anticoagulant functions of endothelium, a profile that varies significantly throughout the vasculature. Drs De Paepe and Malfait address heritable collagen disorders such as the Ehlers-Danlos syndromes (EDS), a heterogeneous group of diseases involving the skin, ligaments and joints, blood vessels and internal organs. Most EDS subtypes are caused by mutations in genes encoding fibrillar collagens, or in genes coding for enzymes involved in posttranslational modifications of collagens. Accurate biochemical and molecular testing is now available for most EDS subtypes and can direct genetic counselling and medical management for these disorders. Dr Shovlin reviews recent developments in hereditary haemorrhagic telengiectasia (HHT), a frequently undiagnosed disorder characterized by arteriovenous malformations in multiple organs. These abnormal blood vessels are the result of mutations in one of a number of genes whose protein products influence TGF-beta signalling in vascular endothelial cells. Several HHT management guidelines have been published and are discussed.

[Management of cardiac high risk pregnancy. Caesarean section in a primagravida with cyanotic cardiac defect]

A 37-year-old gravida I with cyanotic heart disease presented for caesarean section in the 31st week of gestation. Caesarean section was performed uneventfully with the patient under epidural anaesthesia accompanied by invasive monitoring. Postoperative echocardiography showed no change in the shunt fraction, volumes or the ventricular function. Every patient with complex comorbidities has to be managed according to individual prerequisites and the experiences and preferences of the team. For such high risk pregnancies regional anaesthesia seems to be a possible option although no clear evidence can be found in the literature.

Preparation and physicochemical characterization of amoxicillin beta-cyclodextrin complexes

Amoxicillin (AMOX), a penicillin A, belongs to the beta-lactam family It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other beta-lactam antibiotics. Its beta-lactamase degradation might be prevented by using a molecular [AMOX:beta-CD] complex. The aim of this work was to prepare complexes using two methods and then characterize interactions between AMOX and the native beta-CD. The extent of complexation in solution has been evaluated by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and 2D rotating-frame Overhauser enhancement spectroscopy (2D ROESY). Mass changes (TG), calorimetric effects (DSC), and mass spectrometry (MS) were determined on the same sample under identical conditions using the Skimmer coupling system. Skimmer and infrared spectroscopy (FT-IR) were used to characterize the solid state of the binary system. Complexation of AMOX with beta-CD was proven by FT-IR, NMR, DSC, and HPLC. The 2D ROESY spectra did not show any dipolar proton interaction of the AMOX with cyclodextrin. The 1:1 stoichiometry of the complex was obtained by HPLC. The stability constant for AMOX with beta-CD was determined to be 1,878 M(-1). In the [AMOX:beta-CD] complex, the phenyl group is included inside the beta-CD, and the ionized carboxyl group on the penam ring forms hydrogen bonds with the secondary hydroxyl groups of another beta-CD to keep the complex stable. Preparation methods allowed exactly the same complex.

The Importance of Oral Health for Cardiothoracic and Vascular Patients

Prior to cardiothoracic or vascular surgery, a patient's oral health is not usually a high priority for the surgical team. Yet, oral neglect often mirrors systemic disease and the need for proper dental care is often unmet. In the perioperative period, the presence of untreated decayed teeth and periodontal disease can result in a potent odontogenic infection with significant consequences. Patients can unknowingly present for such operations with undetected oral infections that can magnify the likelihood of an adverse outcome, increase costs, morbidity, and possibly mortality. Considering scheduling constraints and the urgency of the procedure, a pre-operative dental screening is suggested for patients who undergo elective cardiothoracic or vascular surgery, to ensure that any oral infection is diagnosed and definitively treated. Implementing such an effective and preventive approach can improve surgical outcome and overall patient health.

Antibiotic prophylaxis in oral healthcare - the agreement between Swedish recommendations and evidence

BACKGROUND

Almost all (17/20) Swedish counties have pharmaceutical committees that establish recommendations for the use of antibiotic prophylaxis in oral healthcare.Objective To evaluate the evidence for the use of antibiotic prophylaxis in oral healthcare and the agreement between Swedish recommendations and evidence.

MATERIAL AND METHODS

We conducted a systematic literature search in PubMed and the Cochrane Controlled Trials Register. The MeSH terms 'antibiotic prophylaxis' and 'dentistry' were used in the database search. Abstracts were reviewed according to specific inclusion and exclusion criteria. A total of 186 articles were read in full text by the four authors independently. Data extraction and interpretation of data was carried out using a pre-defined protocol. In the end, one case-control study was included for evaluation of evidence.

RESULTS

The case-control study included patients with specific cardiac conditions. The study reported a 49% protective efficacy (odds ratio: 0.51) of antibiotic prophylaxis for first-time episodes of endocarditis within 30 days of procedure. This result was not statistically significant. The quality of the evidence was low. No studies were evaluated on patients with other medical conditions. The recommendations included several cardiac and other medical conditions for which there is a lack of evidence or no evidence to support the use of antibiotic prophylaxis.

CONCLUSIONS

There is a lack of evidence to support the use of antibiotic prophylaxis. To avoid the risk of adverse events from antibiotics and the risk of developing resistant bacterial strains, the use of antibiotic prophylaxis should be minimised and recommendations in Sweden should be revised to be more evidence-based.

The transcriptional programme of human heart valves reveals the natural history of infective endocarditis

Infective endocarditis (IE) is an infectious disease that is mainly caused by Staphylococcus aureus and Streptococcus sp. It usually leads to valvular destruction and vegetation formation. Its pathophysiology is badly understood and likely involves immune and coagulation systems with close interactions with the microorganism. Our objective was to evaluate host response by comparing transcriptional profiles of cardiac valves from IE patients with controls. Hierarchical clustering revealed a signature of IE consisting of 146 genes. Among the 89 up-regulated genes, we identified two genes strongly associated with IE: metalloproteinase 12 (MMP-12) and aquaporin-9, a member of the aquaglyceroporin membrane channel family. The up-regulation of MMP-12 gene is strengthened by the down-modulation of the gene encoding its inhibitor TIMP3. In addition, MMP-12 was expressed in macrophages infiltrating EI valves. We also found that aquaporin-9 was expressed in endothelial cells lining neo-vessel lumen, suggesting that aquaporin-9 might be associated with neovascularization of infected valves leading to tissue oedema secondary to the inflammatory process. The Gene Ontology annotation and the resulting functional classification showed that most up-regulated genes account for recruitment of inflammatory cells in vegetations, angiogenesis and remodelling of endocardium tissue. A network analysis confirmed the involvement of molecules related to the remodelling of endocardium tissue and angiogenesis in IE. It also evidenced the role of caspases, especially that of caspase-9 and intrinsic apoptotic pathway in IE. Based on this study we propose a scenario for the natural history of IE in humans. Some parameters identified in this work could become tools for measuring the disease activity and should be tested as biomarkers for diagnosis or prognosis assessment in future studies.

Long-term management of the liver transplant patient: recommendations for the primary care doctor

No official document has been published for primary care physicians regarding the management of liver transplant patients. With no official source of reference, primary care physicians often question their care of these patients. The following guidelines have been approved by the American Society of Transplantation and represent the position of the association. The data presented are based on formal review and analysis of published literature in the field and the clinical experience of the authors. These guidelines address drug interactions and side effects of immunosuppressive agents, allograft dysfunction, renal dysfunction, metabolic disorders, preventive medicine, malignancies, disability and productivity in the workforce, issues specific to pregnancy and sexual function, and pediatric patient concerns. These guidelines are intended to provide a bridge between transplant centers and primary care physicians in the long-term management of the liver transplant patient.

Comprehensive evaluation of Streptococcus sanguinis cell wall-anchored proteins in early infective endocarditis

Streptococcus sanguinis is a member of the viridans group of streptococci and a leading cause of the life-threatening endovascular disease infective endocarditis. Initial contact with the cardiac infection site is likely mediated by S. sanguinis surface proteins. In an attempt to identify the proteins required for this crucial step in pathogenesis, we searched for surface-exposed, cell wall-anchored proteins encoded by S. sanguinis and then used a targeted signature-tagged mutagenesis (STM) approach to evaluate their contributions to virulence. Thirty-three predicted cell wall-anchored proteins were identified-a number much larger than those found in related species. The requirement of each cell wall-anchored protein for infective endocarditis was assessed in the rabbit model. It was found that no single cell wall-anchored protein was essential for the development of early infective endocarditis. STM screening was also employed for the evaluation of three predicted sortase transpeptidase enzymes, which mediate the cell surface presentation of cell wall-anchored proteins. The sortase A mutant exhibited a modest (approximately 2-fold) reduction in competitiveness, while the other two sortase mutants were indistinguishable from the parental strain. The combined results suggest that while cell wall-anchored proteins may play a role in S. sanguinis infective endocarditis, strategies designed to interfere with individual cell wall-anchored proteins or sortases would not be effective for disease prevention.

Association between chronic dental infection and acute myocardial infarction

INTRODUCTION

In patients with cardiovascular diseases several risk factors such as high blood pressure, diabetes, smoking and drinking habits, genetic disposition, and chronic inflammation must be considered. The aim of this study was to investigate whether there is a correlation between dental origin infections and the presence of an acute myocardial infarction (AMI).

METHODS

A total of 125 patients who had experienced a myocardial infarction and 125 healthy individuals were included in this study. The oral examination was carried out following the consent of the ethics committee and the National Board for Radiation Protection and included the number of teeth, endodontically treated teeth, periodontal screening index (PSI), clinical attachment level, and radiographic apical lesions (radiograph examination). The medical examination included, among others, blood glucose level, C-reactive protein (CRP) serum levels, and leukocyte number.

RESULTS

The study demonstrated that patients with AMI exhibited an unfavorable dental state of health. After statistical adjustment for age, gender, and smoking, they exhibited a significantly higher number of missing teeth (P = .001), less teeth with root canal fillings (P = .0015), a higher number of radiologic apical lesions (P = .001), and a higher PSI value (P = .001) compared with individuals without myocardial infarction. The medical data showed a nonsignificant correlation between CRP and the number of radiologic apical lesions.

CONCLUSIONS

This study presents evidence that patients who have experienced myocardial infarction also exhibit an unfavorable dental state of health in comparison to healthy patients and suggests an association between chronic oral infections and myocardial infarction.

Bacteraemia due to dental flossing

AIMS

The aims of this study were to (1) investigate the incidence of bacteraemia following flossing in subjects with chronic periodontitis or periodontal health; (2) identify the micro-organisms in detected bacteraemias; and (3) identify any patient or clinical factors associated with such bacteraemia.

MATERIAL AND METHODS

Baseline blood samples were obtained from 30 individuals with chronic periodontitis (17 M:13 F, 29-75 years) and 30 with periodontal health (17 M:13 F, 28-71 years) following a non-invasive examination. Each subject's teeth were then flossed in a standardized manner and blood samples obtained 30 s and 10 min. after flossing cessation. Blood samples were cultured in a BACTEC system and positive samples subcultured for identification.

RESULTS

Forty per cent of periodontitis subjects and 41% of periodontally healthy subjects tested positive for bacteraemia following flossing. Viridans streptococci, which are commonly implicated in infective endocarditis (IE), were isolated from 19% of positive subjects and accounted for 35% of microbial isolates. Twenty per cent of subjects had a detectable bacteraemia at 10 min. post-flossing. No patient or clinical factors were significantly associated with post-flossing bacteraemia.

CONCLUSIONS

Dental flossing can produce bacteraemia in periodontally healthy and periodontally diseased individuals at a rate comparable with that caused by some dental treatments for which antibiotic prophylaxis is given to prevent IE.

Prophylactic antibiotics cannot prevent endoscopic retrograde cholangiopancreatography-induced cholangitis: a meta-analysis

OBJECTIVES

To determine the prophylactic effect of antibiotics on post-endoscopic retrograde cholangiopancreatography (ERCP) cholangitis or sepsis reduction in randomized controlled trials.

METHODS

Databases including MEDLINE, EMBASE, Cochrane Library, and Science Citation Index updated to June 2007 were searched. Main outcome measure was post-ERCP cholangitis or sepsis.

RESULTS

Seven trials were identified, and a total of 1389 patients were included; post-ERCP cholangitis occurred in 5.8% of controls (41/705) versus 3.4% of treated patients (23/684), without statistical significance (relative risk [RR], 0.58; 95% confidence interval [CI], 0.22-1.55). Subsequent sensitivity analysis on trials mainly targeted at patients with suspicious biliary obstruction showed that the incidences of post-ERCP cholangitis were 2.8% (12/425) and 5.4% (24/441) in the antibiotics and control groups, respectively, and this sensitivity analysis did not support antibiotics' preventive effect (RR, 0.33; 95% CI, 0.03-3.32). Another sensitivity analysis exclusively including trials with intravenous route of antibiotics administration also failed to confirm the prophylactic effect of antibiotics (RR, 0.53; 95% CI, 0.18-1.60).

CONCLUSIONS

Antibiotics cannot significantly prevent ERCP-induced cholangitis in unselected patients and should not be routinely recommended. Yet, more trials including patients with predicted incomplete biliary drainage are still required to prove the effectiveness of prophylactic antibiotics in this setting.

A rare infectious complication after endoscopic ultrasound guided fine needle aspiration in an oncological patient and review of the literature

An endoscopic ultrasound guided fine needle aspiration of a mediastinal lymph node was performed in a cancer patient. Shortly after this procedure, a streptococcus salivarius endocarditis was diagnosed. To our knowledge, this is the first case in the literature of endocarditis following ultrasound guided fine needle aspiration in the absence of cardiac risk factors.

Early wound healing following one-stage dental implant placement with and without antibiotic prophylaxis: a pilot study

BACKGROUND

One-stage implant placement has clinically acceptable treatment outcomes. Among other advantages, it may allow investigation of early wound healing. The purpose of this pilot study was to determine whether peri-implant crevicular fluid (PICF) can be used to detect early changes around implants placed with one-stage surgical protocol following 1 week of healing.

METHODS

Twenty subjects (11 males and nine females; aged 22 to 72 years; two smokers) were included. Exclusion criteria were allergies to amoxicillin and systemic conditions that may affect healing. Subjects had a healthy periodontium and needed a single implant; eight received antibiotic prophylaxis, and 12 served as controls. Clinical healing was evaluated with plaque and gingival indices (PI and GI, respectively). Gingival crevicular fluid (GCF) from the surgical site was obtained prior to the surgery, whereas PICF was collected at the 1-week visit. Enzyme-linked immunosorbent assay was used to determine GCF/PICF interleukin (IL)-1beta and -8 concentrations. Peripheral blood and GCF antibiotic levels were measured by high-performance liquid chromatography.

RESULTS

Postoperative PI and GI were slightly increased. Total GCF and PICF volumes did not show a significant difference between appointments. There was an increase in PICF IL-1beta and -8 levels at 1 week postoperatively. Mean amoxicillin serum concentration was 5.1 +/- 2 microg/ml at 1 to 4 hours following the initial dose, whereas GCF amoxicillin levels were below the limit of detection. Antibiotic prophylaxis had a modest effect on clinical indices (PI and GI) and no appreciable effect on biomarkers.

CONCLUSIONS

PICF content can be studied as early as 1 week following one-stage implant placement. The results raise doubts regarding the clinical usefulness of amoxicillin prophylaxis.

Antimicrobial therapy in periodontitis: the use of systemic antimicrobials against the subgingival biofilm

OBJECTIVES

The aim was to answer three relevant questions: can systemic antimicrobials be efficacious if the biofilm is not disrupted? Can the type of debridement of the subgingival biofilm impact upon the clinical outcomes of the adjunctive antimicrobial therapy? Is the efficacy of the adjunctive systemic antimicrobial therapy dependent on the quality of the debridement of the subgingival biofilm and the sequence debridement-antibiotic usage?

MATERIAL AND METHODS

Relevant papers were searched, critically analysed and their data were extracted.

RESULTS

For the first question, studies assessing susceptibility of bacteria in biofilms, and clinical studies evaluating systemic antimicrobials as monotherapy, were reviewed. For the second question, clinical studies comparing systemic antimicrobials as adjuncts to non-surgical debridement or to periodontal surgery and clinical trials using systemic antibiotics with periodontal surgery were evaluated. For the third question, a previous systematic review was updated.

CONCLUSION

If systemic antimicrobials are indicated in periodontal therapy, they should be adjunctive to mechanical debridement. There is not enough evidence to support their use with periodontal surgery. Indirect evidence suggests that antibiotic intake should start on the day of debridement completion, debridement should be completed within a short time (preferably <1 week) and with an adequate quality, to optimize the results.

Post-NICE 2008: Antibiotic prophylaxis prior to dental procedures for patients with pulmonary arteriovenous malformations (PAVMs) and hereditary haemorrhagic telangiectasia

Recently published guidance from NICE highlights that antibiotic prophylaxis is no longer required for patients with structural heart disease at risk of infective endocarditis. The American Heart Association has published similarly less interventive guidance. Individuals with pulmonary arteriovenous malformations and hereditary haemorrhagic telangiectasia are at risk of brain abscess from dental bacteraemias. In this article we explore why these patients do not fall into the groups considered by NICE and provide recommendations to reduce their risks of dental bacteraemias, including optimising dental hygiene and use of antibiotic prophylaxis prior to dental procedures.

Streptococcal Infections

The streptococci are a large heterogeneous group of gram-positive spherically shaped bacteria widely distributed in nature. They include some of the most important agents of human disease as well as members of the normal human flora. Some streptococci have been associated mainly with disease in animals, while others have been domesticated and used for the culture of buttermilk, yogurt, and certain cheeses. Those known to cause human disease comprise two broad categories: First are the pyogenic streptococci, including the familiar β-hemolytic streptococci and the pneumococcus. These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts. Second are the more diverse enteric and oral streptococci, which are nearly always part of the normal flora and which are more frequently associated with opportunistic infections.

The uptake of apoptotic cells drives Coxiella burnetii replication and macrophage polarization: a model for Q fever endocarditis

Patients with valvulopathy have the highest risk to develop infective endocarditis (IE), although the relationship between valvulopathy and IE is not clearly understood. Q fever endocarditis, an IE due to Coxiella burnetii, is accompanied by immune impairment. Patients with valvulopathy exhibited increased levels of circulating apoptotic leukocytes, as determined by the measurement of active caspases and nucleosome determination. The binding of apoptotic cells to monocytes and macrophages, the hosts of C. burnetii, may be responsible for the immune impairment observed in Q fever endocarditis. Apoptotic lymphocytes (AL) increased C. burnetii replication in monocytes and monocyte-derived macrophages in a cell-contact dependent manner, as determined by quantitative PCR and immunofluorescence. AL binding induced a M2 program in monocytes and macrophages stimulated with C. burnetii as determined by a cDNA chip containing 440 arrayed sequences and functional tests, but this program was in part different in monocytes and macrophages. While monocytes that had bound AL released high levels of IL-10 and IL-6, low levels of TNF and increased CD14 expression, macrophages that had bound AL released high levels of TGF-beta1 and expressed mannose receptor. The neutralization of IL-10 and TGF-beta1 prevented the replication of C. burnetii due to the binding of AL, suggesting that they were critically involved in bacterial replication. In contrast, the binding of necrotic cells to monocytes and macrophages led to C. burnetii killing and typical M1 polarization. Finally, interferon-gamma corrected the immune deactivation induced by apoptotic cells: it prevented the replication of C. burnetii and re-directed monocytes and macrophages toward a M1 program, which was deleterious for C. burnetii. We suggest that leukocyte apoptosis associated with valvulopathy may be critical for the pathogenesis of Q fever endocarditis by deactivating immune cells and creating a favorable environment for bacterial persistence.

Identification of Streptococcus sanguinis genes required for biofilm formation and examination of their role in endocarditis virulence

Streptococcus sanguinis is one of the pioneers in the bacterial colonization of teeth and is one of the most abundant species in the oral biofilm called dental plaque. S. sanguinis is also the most common viridans group streptococcal species implicated in infective endocarditis. To investigate the association of biofilm and endocarditis, we established a biofilm assay and examined biofilm formation with a signature-tagged mutagenesis library of S. sanguinis. Four genes that have not previously been associated with biofilm formation in any other bacterium, purB, purL, thrB, and pyrE, were putatively identified as contributing to in vitro biofilm formation in S. sanguinis. By examining 800 mutants for attenuation in the rabbit endocarditis model and for reduction in biofilm formation in vitro, we found some mutants that were both biofilm defective and attenuated for endocarditis. However, we also identified mutants with only reduced biofilm formation or with only attenuation in the endocarditis model. This result indicates that the ability to form biofilms in vitro is not associated with endocarditis virulence in vivo in S. sanguinis.

EmaA, a potential virulence determinant of Aggregatibacter actinomycetemcomitans in infective endocarditis

The gram-negative fastidious human oropharyngeal Aggregatibacter actinomycetemcomitans is implicated in the etiology of infective endocarditis. EmaA, an oligomeric coiled-coil adhesin homologous to YadA of Yersinia enterocolitica, was hypothesized to mediate the interaction of A. actinomycetemcomitans with collagen. Collagen, the most abundant protein in human bodies and the main component of extracellular matrix (ECM), predominates in the supporting tissue of cardiac valves. To extend our earlier studies using purified collagen to determine bacterial binding activities, we developed a tissue model using rabbit cardiac valves to investigate the interaction of A. actinomycetemcomitans with native collagen. The resected mitral valves, with or without removal of the endothelium, were incubated with equivalent numbers of the wild type and the isogenic emaA mutant defective in collagen binding. There was no difference in binding between the wild-type and the mutant strains when the endothelium remained intact. However, the emaA mutant was fivefold less effective than the wild-type strain in colonizing the exposed ECM. A 10-fold increase in the binding of the wild-type strain to ECM was observed compared with the intact endothelium. Similar observations were replicated in an in vivo endocarditis rabbit model; the emaA mutant was 10-fold less effective in the initial infection of the traumatized aortic valve. Colocalization studies indicated that A. actinomycetemcomitans bound to type I collagen. A. actinomycetemcomitans preferentially colonized the ECM and, together with the evidence that EmaA interacts with the native collagen, suggested that the adhesin is likely a potential virulence determinant of the bacterium in the initiation of infective endocarditis.

Rendu-Osler-Weber disease: update of medical and dental considerations

Rendu-Osler-Weber disease, also known as hereditary hemorrhagic telangiectasia (HHT), is an autosomal dominant inherited disorder characterized by an aberrant vascular development. The reported prevalence is approximately 1 per 5,000-10,000. The clinical manifestations consist of recurrent spontaneous nosebleeds, telangiectasias characteristically at the lips, oral cavity, fingers, and nose, and visceral arteriovenous malformations. Timely recognition of this syndrome makes screening for complications, preventive measurements, and genetic counselling possible. The important role of the dental profession in the recognition of this genetic disease is emphasized. In addition, a brief overview of the current literature is presented.

Endocarditis Prophylaxis in Cardiac Patients: Knowledge among General Dental Practitioners in Tabriz

Background and aims

Dental procedures injuring oral tissues may induce bacterial release to blood stream that can cause infective endocarditis in susceptible patients. The aim of this study was to determine the level of knowledge of general dental practitioners (GDPs) in Tabriz, Northwest of Iran, regarding endocarditis prophylaxis in cardiac pa-tients receiving dental treatments.

Materials and methods

This was a cross-sectional, descriptive, analytical study that included 150 GDPs. All practitioners were given a self-administered questionnaire which consisted of three parts assessing their knowledge of cardiac diseases requiring prophylaxis, dental procedures requiring prophylaxis, and antibiotic regimen for endocarditis prophylaxis. Statistical analysis of data was carried out using independent t-test, one-way ANOVA and chi-square test.

Results

The level of knowledge among GDPs in three areas of cardiac diseases requiring prophylax-is, dental procedures requiring prophylaxis, and antibiotic regimen for endocarditis prophylaxis were 63.7%, 66.8% and 47.7%, respectively. Their overall level of knowledge regarding endocarditis prophylaxis was 59%. Association of the level of knowledge with age and practice period was statis-tically significant (P < 0.05). However, the level of knowledge was not significantly associated with gender or university of graduation in either of three areas evaluated (P > 0.05).

Conclusion

According to our results, the knowledge of endocarditis prophylaxis among GDPs in Tabriz was in a moderate level. Regarding the importance of endocarditis prophylaxis in sus-ceptible patients, it should be more emphasized in the curriculum of dental schools and continuing dental education programs.