Infective endocarditis, dentistry and antibiotic prophylaxis; time for a rethink?

Contribution of collagen-binding protein Cnm of Streptococcus mutans to induced IgA nephropathy-like nephritis in rats

IgA nephropathy (IgAN), the most common primary glomerulonephritis, is considered an intractable disease with unknown pathogenic factors. In our previous study, Streptococcus mutans, the major causative bacteria of dental caries, which expresses Cnm, was related to the induction of IgAN-like nephritis. In the present study, the Cnm-positive S. mutans parental strain, a Cnm-defective isogenic mutant strain, its complementation strain, and recombinant Cnm (rCnm) protein were administered intravenously to Sprague Dawley rats, and the condition of their kidneys was evaluated focusing on the pathogenicity of Cnm. Rats treated with parental and complement bacterial strains and rCnm protein developed IgAN-like nephritis with mesangial proliferation and IgA and C3 mesangial deposition. Scanning immunoelectron microscopy revealed that rCnm was present in the electron-dense deposition area of the mesangial region in the rCnm protein group. These results demonstrated that the Cnm protein itself is an important factor in the induction of IgAN in rats.

Association between severity of dental caries and the risk of stroke

OBJECTIVE

The relationship between dental caries and stroke remains inconclusive. The aim of this study is to investigate whether different severities of dental caries affect the risk of stroke.

METHODS

This retrospective cohort study was conducted using the 2000-2013 Taiwan National Health Insurance Database. We selected 23,662 patients with advanced/severe dental caries and 23,662 patients with incipient/moderate dental caries between 2000 and 2006. These patients were followed to the occurrence of stroke or to the end of the study in 2013. Hazard ratios (HRs) and 95% confidence intervals (CIs) derived from the Cox proportional hazards models were calculated to assess the association between severity of dental caries and the risk of stroke.

RESULTS

The advanced/severe dental caries group had a significantly higher risk of stroke compared with incipient/moderate dental caries group (adjusted HR, 1.16; 95% CI, 1.03-1.31). Stratified analyses showed that advanced/severe dental caries was positively associated with the risk of ischemic stroke in patients aged ≥40 years and with the risk of hemorrhagic stroke in patients aged <40 years.

CONCLUSION

There is a severity-dependent association between dental caries and stroke in an Asian population.

The level of knowledge of medical and dental students regarding prophylaxis for infective endocarditis

OBJECTIVES

Infective endocarditis is a rarely seen disease, but has a high mortality rate. Therefore, it is extremely important that the guidelines are followed correctly. The main aim of this study was to evaluate and compare the level of knowledge and attitude of infective endocarditis of fourth- and fifth-year dentistry students in clinical residency and fifth- and sixth-year medical students.

METHODS

A 42-item questionnaire evaluating the type and dosage of antibiotics administered as infective endocarditis prophylaxis in medical conditions and dentistry procedures was delivered online to the study participants. The data obtained were examined using descriptive statistics and analyzed with the chi-square test.

RESULTS

The questionnaire was completed by a total of 332 participants. The statistical analyses showed a good level of knowledge in 55% of the dentistry faculty students and in 43.5% of the medical faculty students.

CONCLUSIONS

When considering that dental and medical faculty students are not expected to receive additional training on antimicrobial management after graduation, the findings of this study have raised significant attitude for the improvement of our education system in this field.

Microbiota present in combined endodontic-periodontal diseases and its risks for endocarditis

INTRODUCTION

Infective endocarditis (IE) is an inflammatory disease usually caused by bacteria that enter the bloodstream and establish infections in the inner linings or valves of the heart, including blood vessels. Despite the availability of modern antimicrobial and surgical treatments, IE continues to cause substantial morbidity and mortality. Oral microbiota is considered one of the most significant risk factors for IE. The objective of this study was to evaluate the microbiota present in root canal (RC) and periodontal pocket (PP) clinical samples in cases with combined endo-periodontal lesions (EPL) to detect species related to IE using NGS.

METHODS

Microbial samples were collected from 15 RCs and their associated PPs, also from 05 RCs with vital pulp tissues (negative control, NC). Genomic studies associated with bioinformatics, combined with structuring of a database (genetic sequences of bacteria reported for infective endocarditis), allowed for the assessment of the microbial community at both sites. Functional prediction was conducted using PICRUSt2.

RESULTS

Parvimonas, Streptococcus, and Enterococcus were the major genera detected in the RCs and PPs. A total of 79, 96, and 11 species were identified in the RCs, PPs, and NCs, respectively. From them, a total of 34 species from RCs, 53 from PPs, and 2 from NCs were related to IE. Functional inference demonstrated that CR and PP microbiological profiles may not be the only risk factors for IE but may also be associated with systemic diseases, including myocarditis, human cytomegalovirus infection, bacterial invasion of epithelial cells, Huntington's disease, amyotrophic lateral sclerosis, and hypertrophic cardiomyopathy. Additionally, it was possible to predict antimicrobial resistance variants for broad-spectrum drugs, including ampicillin, tetracycline, and macrolides.

CONCLUSION

Microorganisms present in the combined EPL may not be the only risk factor for IE but also for systemic diseases. Antimicrobial resistance variants for broad-spectrum drugs were inferred based on PICRUSt-2. State-of-the-art sequencing combined with bioinformatics has proven to be a powerful tool for conducting studies on microbial communities and could considerably assist in the diagnosis of serious infections.

CLINICAL RELEVANCE

Few studies have investigated the microbiota in teeth compromised by combined endo-periodontal lesions (EPL), but none have correlated the microbiological findings to any systemic condition, particularly IE, using NGS techniques. In such cases, the presence of apical periodontitis and periodontal disease can increase IE risk in susceptible patients.

Risk Assessment of Cnm-Positive Streptococcus mutans in Stroke Survivors (RAMESSES): Protocol for a Multicenter Prospective Cohort Study

Introduction

The role of commensal microbiota in systemic diseases, including brain diseases, has attracted increasing attention. Oral infectious diseases, such as dental caries and periodontitis, are also involved in cerebrovascular diseases and cognitive impairment. Cerebral microbleeds (CMBs) and intracerebral hemorrhage due to small vessel disease (SVD), are presumably associated with a high risk of vascular cognitive impairment and stroke. We previously reported that Streptococcus mutans (S. mutans, the main pathogen of dental caries), harboring the cnm gene that encodes the collagen-binding protein Cnm, is associated with the development of hypertensive intracerebral hemorrhage and aggravation of CMBs. We also proposed a mechanism by which the circulating Cnm-expressing S. mutans causes intracerebral hemorrhage or CMBs; it binds to denuded basement membranes mainly composed of collagen IV through damaged tight junctions or it directly invades endothelial cells, resulting in blood-brain barrier injury. In November 2018, we initiated a multicenter, prospective cohort study (RAMESSES: Risk Assessment of Cnm-positive S. mutans in Stroke Survivors; UMIN Clinical Trials Registry: UMIN000045559) to explore the longitudinal association between Cnm-positive S. mutans and CMBs with comprehensive dental findings, which should determine the effect of Cnm-positive S. mutans in the oral cavity on the risk of CMB development and cognitive decline.

Methods

Fifteen domestic institutes will be enlisted to enroll 230 patients who have at least one CMB in the deep brain area and develop a stroke within the past year. The prevalence of Cnm-positive S. mutans based on oral specimens and dental hygiene will be examined. The primary outcome is the number of newly developed deep CMBs. The secondary outcomes include the new development of lobar, subtentorial, or any type of CMBs; symptomatic intracerebral hemorrhage or ischemic stroke; changes in cognitive function or frailty; major bleeding; all-cause mortality; and antibody titers against periodontal pathogens. The observation period will be 2 years.

Discussion

The 2-year longitudinal prospective cohort study is expected to establish the role of Cnm-positive S. mutans in SVD including CMBs and intracerebral hemorrhage from the perspective of the “brain-oral axis” and provide guidance for novel prophylactic strategies against Cnm-positive S. mutans-induced SVD.

Environmental, Microbiological, and Immunological Features of Bacterial Biofilms Associated with Implanted Medical Devices

The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings, and it has been the subject of many studies in the past few years, with most of them focused on prosthetic joint infections. We review here recent works on biofilm formation and microbial colonization on a large variety of indwelling devices, ranging from heart valves and pacemakers to urological and breast implants and from biliary stents and endoscopic tubes to contact lenses and neurosurgical implants. We focus on bacterial abundance and distribution across different devices and body sites and on the role of environmental features, such as the presence of fluid flow and properties of the implant surface, as well as on the interplay between bacterial colonization and the response of the human immune system.

PERIODONTAL AND SYSTEMIC DISEASES: ERECTILE DYSFUNCTION

Periodontal hastalıklar toplumda yaygın bir şekilde görülmektedir. Son yıllarda yapılan çalışmalarla periodontal hastalıkların sistemik hastalıklara, benzer şekilde sistemik rahatsızlıklarında periodontal hastalıklara katkıda bulunabileceği bilinmektedir. Periodontal hastalıklar ve sistemik hastalıklar arasındaki bu iki yönlü ilişki son yıllarda dikkat çekici bir şekilde araştırmalara neden olmuştur. Bu konulardan biri de erektil disfonksiyondur. Periodontal hastalıkların erektil disfonksiyon ile ilişkisi ilgi çekicidir. Farklı etyolojiye sahip olan erektil disfonksiyonda periodontal hastalıkların etkisi son dönemde sıkça araştırılmıştır. Bu geleneksel derlemede, tedavi sağlayıcılara periodontal hastalıkların genel özellikleri, erektil disfonksiyonun genel özellikleri ve birbiri ile olan ilişkiler üzerinde durulacaktır.

Involvement of Tunisian General Practitioners in the Management of Patients at Risk of Infective Endocarditis: A Cross-Sectional Study

Objectives

This work aimed to estimate the knowledge and practice of general dentists in the governorate of Manouba regarding the management of patients at risk of infective endocarditis.

Materials and Methods

A survey involving private sector general dentists in the governorate of Manouba was performed. It contained 21 questions, and it was addressed to 111 dentists. Only 82 dentists responded. To carry out the descriptive study, we used the SPSS software version 21.0.

Results

Our results proved the lack of knowledge among dentists in the governorate of Manouba with regard to the management of patients at risk of infective endocarditis. An overestimation of the risk and an overprescription of antibiotic were found in order to ensure an over-protection for the patients as well as the dentist. In fact, 85.4% of these dentists prescribed antibiotic prophylaxis for the two groups of patients (high risk and moderate risk). Only 9.8% followed the right modality of antibiotic prophylaxis prescription; 4.9% of the dentists prescribed antibiotic only 1 hour before the act and 4.9% of them prescribed antibiotic 1 hour before the act and continued the treatment in case of the presence of an infectious site.

Conclusion

A discrepancy towards an over-estimation of risk and overprescription of antibiotic was found between the recommendations and real practice. Similar studies in the other governorates of Tunisia are recommended in order to better understand the problem.

Evaluation of the Current Knowledge About Bacterial Endocarditis Prevention Among General Dentists in the City of Santo Domingo, Dominican Republic

Infective endocarditis (IE) is a life-threatening disease caused by bacterial adherence to the lining of the heart and heart valve, and it can be caused by bacterial contamination of the bloodstream during invasive dental procedures. The American Heart Association (AHA) recommended guidelines for antibiotic prophylaxis in 2008 before invasive dental procedures; however, in the Dominican Republic, no official guidelines or regulations on this topic have been yet established. This study aimed to evaluate the current knowledge about bacterial endocarditis prevention among dentists in Santo Domingo. The study participants were dentists who attended a conference organized by Universidad Federico Henríquez y Carvajal (n = 95), of which 74 responded to the questionnaire survey. Seventy-eight percentage of the participants responded that an indication of antibiotics is recommended in cases of prophylaxis for IE. The prescription of antibiotics was applied to patients with prosthetic valves (78.4%), presented a history of previous IE (77%) among others. Among all the interventions in which the respondents would prescribe antibiotics, tooth extraction (70.7%) was the most frequent. Amoxicillin was the preferred drug choice (63.5%) and clindamycin was the antibiotic of choice in allergic patients (55.4%). Even though the choice of antibiotics were according to AHA guidelines (2008), majority of the dentists (58.82 and 55.4%) were not aware of the correct dosage and timing of administration of azithromycin and clindamycin in drugs in patients allergic to penicillin.

Contribution of Severe Dental Caries Induced by Streptococcus mutans to the Pathogenicity of Infective Endocarditis

Streptococcus mutans, a major pathogen of dental caries, is regarded as a causative agent of infective endocarditis (IE), which mainly occurs in patients with underlying heart disease. However, it remains unknown whether severe dental caries that extend to pulp space represent a possible route of infection. In the present study, we evaluated the virulence of S. mutans for IE development using rats with concurrent severe dental caries and heart valve injury. Dental caries was induced in rats through the combination of a caries-inducing diet and the administration of S. mutans into the oral cavity. Then, the heart valves of a subset of rats were injured using a sterile catheter and wire under general anesthesia. The rats were euthanized at various times with various stages of dental caries. The number of teeth affected by dental caries with pulp exposure was increased in the rats in a time-dependent manner. S. mutans was recovered from injured heart tissue, which was mainly observed in rats with higher number of S. mutans bacteria in mandibular bone and a larger number of teeth in which caries extended to pulp. Dental caries was more severe in rats with heart injury than in rats without heart injury. Sequencing analysis targeting 16S rRNA revealed that specific oral bacteria appeared only in rats with heart injury, which may be related to the development of dental caries. Our findings suggest that dental caries caused by the combination of S. mutans infection and sucrose intake may contribute to S. mutans colonization in injured heart tissue.

Antibiotic prophylaxis for the prevention of infective endocarditis for dental procedures is not associated with fatal adverse drug reactions in France

Background

One of the major reasons to stop antibiotic prophylaxis (AP) to prevent infective endocarditis (IE) in the United Kingdom but not in the rest of the world was that it would result in more deaths from fatal adverse drug reactions (ADRs) than the number of IE deaths. The main aim of this study was to quantify and describe the ADRs with amoxicillin or clindamycin for IE AP. The second aim was to infer a crude incidence of anaphylaxis associated with amoxicillin for IE AP.

Material and Methods

The Medical Dictionary for Regulatory Activities (MedDRA) was used to group ADRs for IE AP using the broad Standardized MedDRA Queries “Anaphylactic reaction, Amoxicillin, Clindamycin, Clostridium Difficile infection” to the French Pharmacovigilance Database System. From this first-line collection, we selected all cases occurring for IE AP and ultimately, the cases for IE AP for a dental procedure. Then, each case was analyzed.

Results

Of 11639 first-line recorded ADRs, 100 were for IE AP but no fatal anaphylaxis to amoxicillin or clindamycin and no C. difficile infection associated with clindamycin were identified. Only 17 cases of anaphylaxis to amoxicillin related to dental procedures were highlighted. The estimation of the crude incidence rate of anaphylaxis associated with amoxicillin for IE AP for invasive dental procedure was 1/57 000 (95% CI 0.2-0.6).

Conclusions

Fatal or severe ADRs with amoxicillin or clindamycin is not a rational argument to stop IE AP before invasive dental procedures.

Key words:Infective endocarditis, antibiotic prophylaxis, anaphylaxis, adverse drug reaction, amoxicillin, clindamycin, pharmacovigilance.

Current knowledge among Japanese experienced general dentists regarding prevention of infective endocarditis

Infective endocarditis (IE), a life-threatening condition predominantly occurring in patients with underlying heart disease, is mainly caused by bacteremia induced by invasive dental treatment. However, the amount of related information shared between cardiologists and dentists appears to be inadequate. In the present study, a survey regarding prevention of IE, composed of 13 major questions, 2 of which also allowed free comments, was sent to approximately 3000 dentists belonging to a prefectural dental association in Japan. Of the 13.6% who returned the forms, more than 80% were general dentists with more than 20 years of experience. Approximately, 55% of the responders reported that they had opportunities to prescribe antibiotics prior to performing treatments with risk of IE, though noted difficulties with designation of which patients with heart disease were at risk. Most of the dentists considered that oral surgery procedures have a high risk for IE, whereas less invasive procedures were considered to be not associated with the disease. Approximately, 35% selected oral amoxicillin, with a dose of 2.0 g (20%) or 500 mg (27%) prescribed for adults, and 50 mg (10%) or 30 mg (12%) per kg of body weight for children. However, the timing of the antibiotics administration varied. The present results reveal current knowledge regarding prevention of IE among general dentists in Japan, and should be valuable for construction of a protocol to establish consensus between dentists and cardiologists.

Longitudinal comparison of Streptococcus mutans-induced aggravation of non-alcoholic steatohepatitis in mice

Background: We previously reported that intravenous administration of Streptococcus mutans strain TW871 caused typical non-alcoholic steatohepatitis (NASH)-like findings in a high-fat diet (HFD) mouse model at 16 weeks after initiating the experiment.

Objective: The purpose of the present study was to analyse mice administered S. mutans TW871 fed a HFD for various periods of time.

Methods: First, 6-week-old C57BL/6J mice were fed an HFD for 4 weeks, then TW871 (1 × 10⁷ CFU) or phosphate-buffered saline (PBS) were intravenously administered. Mice were euthanized 12, 16, 20, and 48 weeks after starting the experiment, and conventional clinical and histopathological evaluations were performed.

Results: Typical NASH-like findings were not identified in the mice at 12 weeks, while they were observed in the TW871 group at 16 weeks, and the severity of NASH symptoms were increased at 20 weeks. Furthermore, signs of severe NASH were also observed at 48 weeks. In contrast, in the PBS-administered group, the NASH findings were identified only at 48 weeks and no typical NASH features were observed at 12, 16, or 20 weeks.

Conclusion: These results suggest that intravenous administration of a specific S. mutans strain aggravates NASH in a time-dependent manner in the mice in contrast to mice without S. mutans exposure.

Contribution of the Collagen-Binding Proteins of Streptococcus mutans to Bacterial Colonization of Inflamed Dental Pulp

Streptococcus mutans is a major pathogen of dental caries. Collagen-binding proteins (CBPs) (approximately 120 kDa), termed Cnm and Cbm, are regarded as important cell surface antigens related to the adherence of S. mutans to collagenous tissue. Furthermore, CBP-positive S. mutans strains are associated with various systemic diseases involving bacteremia, such as infective endocarditis. Endodontic infection is considered to be an important cause of bacteremia, but little is known regarding the presence of S. mutans in dental pulp tissue. In the present study, the distribution and virulence of S. mutans in dental pulp tissues were investigated by focusing on CBPs. Adhesion and invasion properties of various S. mutans strains were analyzed using human dental pulp fibroblasts (HDPFs). CBP-positive strains had a significantly higher rate of adhesion to HDPFs compared with CBP-defective isogenic mutant strains (P<0.001). In addition, CBP-positive strains induced HDPF proliferation, which is a possible mechanism related to development of hyperplastic pulpitis. The distribution of S. mutans strains isolated from infected root canal specimens was then analyzed by PCR. We found that approximately 50% of the root canal specimens were positive for S. mutans. Approximately 20% of these strains were Cnm-positive, while no Cbm-positive strains were isolated. The Cnm-positive strains isolated from the specimens showed adhesion to HDPFs. Our results suggest that CBP-positive S. mutans strains exhibit high colonization in dental pulp. This could be a possible virulence factor for various systemic diseases.

Assessment of knowledge of dental staff at a saudi arabian university regarding the prophylaxis for infective endocarditis

The use of prophylactic antibiotics for the prevention of infective endocarditis following dental procedures has long been debated and there is still confusion regarding its efficacy. As a result, the prophylactic treatment varies considerably amongst different countries across the world and amongst different dental practitioners.

Aggravation of inflammatory bowel diseases by oral streptococci

OBJECTIVES

Streptococcus mutans can aggravate colitis in mice. We evaluated the virulence of colitis using type strains as well as blood isolates of several oral streptococcal species.

MATERIALS AND METHODS

We investigated the susceptibility of blood isolates of several oral streptococci to phagocytosis, adhesion to and invasion of hepatic cells and interferon-γ secretion. A mouse model of dextran sodium sulphate-induced colitis was used to evaluate bacterial aggravation of colitis. In addition, interferon-γ antibody was administered to mice with prominent aggravation of colitis.

RESULTS

In vitro analyses showed that Streptococcus sanguinis ATCC 10556 was a possible virulent strain among type strains of several oral streptococci, and that analysis of blood isolates of S. sanguinis TW289 revealed a potential virulent strain. Intravenous administration of ATCC 10556 and TW289 caused prominent aggravation of dextran sodium sulphate-induced colitis, and histopathological examinations showed that interferon-γ secretion due to infection of hepatic cells caused colitis aggravation. Administration of interferon-γ antibody suppressed TW289-induced colitis.

CONCLUSION

These results suggest that some virulent oral streptococcal strains are associated with the aggravation of colitis induced by enhanced secretion of interferon-γ when they invade the bloodstream.

Knowledge of General Dentists and Senior Dental Students in Iran about Prevention of Infective Endocarditis

Infective endocarditis (IE) is an infection of the endothelial surface of the heart and heart valves with serious, even fatal, complications and that often requires long-term and expensive treatment. Dental procedures may lead to IE in high-risk patients. The aim of this study was to evaluate and compare the knowledge of general dentists and dental students concerning the prevention of IE in Hamadan, Iran. In this cross-sectional study, the awareness of general dentists and dentistry students concerning the prevention of IE was evaluated during 2010. A questionnaire was prepared and administered to 58 final-year dental students and 96 general dental practitioners in Hamadan. A total of 154 persons completed the questionnaire. The questionnaire consisted of some demographic questions and questions about awareness of IE in three sections. The gathered data were analyzed by using descriptive statistics, Pearson's chi-square test, Mann-Whitney test, and independent t-tests. The gathered data showed that dentistry students answered the questions about awareness of the prevention of IE more correctly than did general dentists. The overall knowledge of endocarditis prophylaxis among students and dentists was about 65% and 56%, respectively. The students' knowledge was better because 94.9% of the students had desired (acceptable) and relatively desired knowledge; this result for dentists, however, was 82.3%. In our study, the overall awareness level of the study population was moderate. Dentist and students believed that patients with prosthetic valves and previous IE were the most common cardiac disease cases that required prophylaxis. The most common prophylactic regimen was in accordance with the guidelines of the American Heart Association and was a single dose of 2 g amoxicillin 1 hour before treatment. The results indicated that gender had no effect on the level of knowledge; however, there was a statistically significant relationship between age and level of knowledge.

Clarithromycin suppresses the periodontal bacteria-accelerated abdominal aortic aneurysms in mice

BACKGROUND AND OBJECTIVE

Although clarithromycin (CAM) has many biological functions, including regulation of MMPs, little is known about its effect on abdominal aortic aneurysms. Periodontopathic bacteria have been reported to be associated with several kinds of circulatory diseases. The purpose of this study was therefore to clarify the effect of CAM on periodontopathic bacteria-accelerated abdominal aortic aneurysms.

MATERIAL AND METHODS

Abdominal aortic aneurysm was produced in mice by the peri-aortic application of 0.25 m CaCl(2). The mice were inoculated once per week with live Porphyromonas gingivalis, which is one of the major periodontopathic bacteria. Test mice (n=8) were given a daily oral dose of CAM, while control mice (n=13) were not.

RESULTS

Four weeks after the operation, the P. gingivalis-injected and CAM-treated mice showed a significant decrease in the aortic diameter in comparison with the mice only injected with P. gingivalis. Histopathologically, the samples obtained from the P. gingivalis-injected and CAM-treated mice showed less elastic degradation. Moreover, the plasma MMP-2 concentration of the CAM-treated mice decreased significantly.

CONCLUSION

These findings suggest that CAM administration is useful to suppress periodontal bacteria-accelerated abdominal aortic aneurysms via MMP regulation.

Streptococcus mutans: a rare cause of retroperitoneal abscess

Retroperitoneal abscesses are uncommonly encountered clinical entities and they represent serious surgical infections associated with significant mortality rates because of their insidious clinical manifestations and diagnostic difficulty. The source of retroperitoneal infections is usually an organ contained within or abutting the retroperitoneum, usually the kidney and the microorganisms most commonly isolated are gram-negative bacilli. Gram-positive cocci, mainly staphylococcal species and rarely streptococcal species, are a less common cause of retroperitoneal abscess and are usually isolated in cases of hematogenous spread. Treatment of retroperitoneal abscesses includes identification and treatment of underlying conditions, intravenous antibiotics and adequate surgical drainage of all well-defined collections. We present a rare case of retroperitoneal abscess caused by monomicrobial Streprococcus mutans infection and discuss the possible pathogenesis, clinical presentation, diagnosis and treatment.

Oral health status of normal children and those affiliated with cardiac diseases

If a child's general health is compromised, care for his/her oral and dental health becomes an absolute necessity. Children with heart diseases require special dental care because of the risk of developing infective endocarditis.

AIMS AND OBJECTIVES

Was to evaluate the oral health status, parental oral health care knowledge of the pediatric cardiac patients and non cardiac group and infective endocarditis awareness among the parents of the cardiac group.

MATERIALS AND METHODS

Include a total of 50 children with heart diseases and 50 non-cardiac children aged 2-12 years were examined for dental caries index and simplified debris index. A structured, administered questionnaire for parents/caregivers about knowledge of infective endocarditis and oral health were used for data collection.

RESULTS

Showed no statistically significant differences between the caries experience score for the two groups and oral health knowledge. Knowledge about Infective Endocarditis in parents of study group was very poor. Simplified Debris Index of age group 6-12 years was higher in study groups compared to the controls.

CONCLUSION

Improvements should be made in educating parents and children on the importance of caries prevention and maintaining a good oral hygiene in prevention of infective endocarditis.

Porphyromonas gingivalis induces myocarditis and/or myocardial infarction in mice and IL-17A is involved in pathogenesis of these diseases

OBJECTIVES

Although an association between periodontitis and cardiovascular diseases has been suggested, the role of Porphyromonas gingivalis in cardiovascular diseases is not clear. In this study, we examined whether experimental bacteremia of P. gingivalis causes cardiovascular diseases and investigated the mechanism of pathogenesis of cardiovascular diseases induced by P. gingivalis.

DESIGN

C57BL/6 mice were intravenously inoculated with 2.0 × 10(8)CFU of P. gingivalis A7436 strain. Mice were sacrificed at specified days and their hearts were collected. The collected organs were divided into two halves and used for histological evaluation and cytokine analysis. IL-17A(-/-), IFN-γ(-/-) and TNF-α(-/-) mice were also intravenously inoculated and the histological changes of hearts in mice were examined.

RESULTS

Myocarditis and/or myocardial infarction were observed in mice injected with P. gingivalis. The levels of IL1-β, IL-6, IL-17A, IL-18, TNF-α and IFN-γ mRNA increased significantly after P. gingivalis injection. In particular, high levels of IL-17A and IFN-γ mRNA expression were observed in hearts of mice after P. gingivalis injection in comparison with these levels before injection. Furthermore, the production of IL-17A was detected in hearts of wild-type mice after P. gingivalis injection. In wild-type, TNF-α(-/-) and IFN-γ(-/-) mice, moderate infiltration of neutrophils and monocytes was observed in hearts at 5 days after injection. In contrast, no inflammatory findings were observed in hearts of IL-17A(-/-) mice.

CONCLUSION

We have demonstrated that an experimental bacteremia of P. gingivalis could induce myocarditis and/or myocardial infarction in mice, and IL-17A plays an important role in the pathogenesis of these diseases.

Induction of experimental endocarditis by continuous low-grade bacteremia mimicking spontaneous bacteremia in humans

Transient high-grade bacteremia following invasive procedures carries a risk of infective endocarditis (IE). This is supported by experimental endocarditis. On the other hand, case-control studies showed that IE could be caused by cumulative exposure to low-grade bacteremia occurring during daily activities. However, no experimental demonstration of this latter possibility exists. This study investigated the infectivity in animals of continuous low-grade bacteremia compared to that of brief high-grade bacteremia. Rats with aortic vegetations were inoculated with Streptococcus intermedius, Streptococcus gordonii or Staphylococcus aureus (strains Newman and P8). Animals were challenged with 10(3) to 10(6) CFU. Identical bacterial numbers were given by bolus (1 ml in 1 min) or continuous infusion (0.0017 ml/min over 10 h). Bacteremia was 50 to 1,000 times greater after bolus than during continuous inoculation. Streptococcal bolus inoculation of 10(5) CFU infected 63 to 100% vegetations compared to 30 to 71% infection after continuous infusion (P > 0.05). When increasing the inoculum to 10(6) CFU, bolus inoculation infected 100% vegetations and continuous infusion 70 to 100% (P > 0.05). S. aureus bolus injection of 10(3) CFU infected 46 to 57% valves. This was similar to the 53 to 57% infection rates produced by continuous infusion (P > 0.05). Inoculation of 10(4) CFU of S. aureus infected 80 to 100% vegetations after bolus and 60 to 75% after continuous infusion (P > 0.05). These results show that high-level bacteremia is not required to induce experimental endocarditis and support the hypothesis that cumulative exposure to low-grade bacteremia represents a genuine risk of IE in humans.

Molecular investigation of macrolide and Tetracycline resistances in oral bacteria isolated from Tunisian children

OBJECTIVE

This study aims to investigate the antibiotic susceptibility of strains isolated from the oral cavity of Tunisian children.

DESIGN

Strains were isolated from the oral cavity of Tunisian children (60 caries-actives and 30 caries-free). Molecular characterization was assessed by PCR assay to detect erythromycin methylase gene (ermB), macrolide efflux (mefI) and tetracycline resistance genes (tetM and tetO).

RESULTS

A total of 21 species were isolated and identified. Antimicrobial susceptibility revealed that the resistance rate to antibiotics was as follow: erythromycin (22%), tetracycline (15.6%), cefotaxim, (7.3%), trimethoprim-sulfamethoxazol (37.6%), nitrofurantoine (2.8%), pristinamycin (17.4%), quinupristin-dalfopristin (15.6%), and rifampicin (3.7%). The majority of mefI positive strains (31.2%) were isolated from the carious children (n=34) in comparison with 8.25% from the control group (n=9). In addition, frequency of strains caring resistance genes were as follow: 12.84% for ermB, 9.17% for tetM and 27.52% for tetO from the carious children in comparison to 0.092%, 3.67% and 3.67% from the caries free group respectively.

CONCLUSION

Multi-resistance strains towards macrolides and tetracycline were recorded. The majority of strains carrying antibiotics resistance genes were isolated from the caries active children. The presence of multi-resistant bacteria in the oral cavity can be the major cause of antibiotic prophylaxis failure in dental practise.

Interferon gamma in the etiology of atherosclerosis and periodontitis

Clinical observations and a few research reports seem to suggest that intraoral infection as well as periodontal teeth could potentially lead to systemic infections including atherosclerosis. The aim of our investigations was to determine whether periodontal disease might aggravate atherosclerosis and whether interferon-gamma (IFNG), widely recognized as a potent multifunctional cytokine, might serve as a marker of the process. This is the first research based on tissue material such as atheromata and periodontal pocket granulation tissue. The study population consisted of 15 patients with periodontitis and atherosclerosis. Control group comprised 15 non-atherosclerotic patients with periodontitis. IFNG, IFNGR1 and IFNGR2 expression was analysed using qRT-PCR profiling in the inflammatory granulation tissue and atheroma. Granulation tissue samples obtained from non-atherosclerotic group showed a significant increase in IFNG and a decrease of IFNGR1, IFNGR2 expression whereas granulation tissue and atheromata of patients with systemic disease demonstrated lower IFNG and higher IFNGR1 and IFNGR2 expression.

Detection of oral streptococci with collagen-binding properties in saliva specimens from mothers and their children

BACKGROUND

Approximately 10-20% of Streptococcus mutans strains have been reported to possess collagen-binding properties, whereas other species in the oral cavity with those properties remain to be elucidated. Aim. To identify strains with collagen-binding properties and analyse their characteristics in comparison with S. mutans.

DESIGN

A total of 110 expectorated saliva specimens were collected from 55 pairs of mothers and their children. Bacterial strains with collagen-binding properties were isolated and the species specified. In addition, strains with collagen-binding properties isolated from mother-child pairs were analysed using molecular biological approaches.

RESULTS

The detection frequency of strains with collagen-binding properties was shown to be 40.9%, among which S. salivarius was the most frequently detected, followed by S. mutans. The collagen-binding activity of the S. mutans group was the highest, followed by S. salivarius. In addition, S. mutans and S. salivarius strains from 3 and 1 mother-child pairs, respectively, were shown to be the same clones.

CONCLUSIONS

Our results indicate that S. mutans and S. salivarius are major species with collagen-binding properties in the oral cavity, and that strains with such properties may be related to mother-child transmission.

Serotype classification of Streptococcus mutans and its detection outside the oral cavity

Streptococcus mutans, generally known as a major pathogen of dental caries, is also a possible causative agent of bacteremia and infective endocarditis. S. mutans is classified into serotypes c, e, f and k based on the chemical composition of serotype-specific polysaccharides, with approximately 70-80% of strains found in the oral cavity classified as serotype c, followed by e (approximately 20%), and f and k (less than 5% each). Serotype k was recently designated as a novel serotype and shown to possess unique features, the most prominent being a defect of the glucose side chain in serotype-specific rhamnose-glucose polymers, which is related to a higher incidence of detection in cardiovascular specimens, owing to phagocytosis resistance. Molecular analyses of cardiovascular specimens showed a high detection frequency for S. mutans DNA, among which the detection rate for serotype k was quite high. These findings suggest that serotype k S. mutans possibly has a high level of virulence for systemic diseases.

Defect of cell wall construction may shield oral bacteria's survival in bloodstream and cause infective endocarditis

Infective endocarditis (IE) is a rare but life-threatening infection. Bacteremia with organisms known to cause IE occurs commonly in association with invasive dental origin. Despite daily oral activities as well as professional dental treatments inducing bacteremia and the dental bacteremia as a risk factor of IE, the details of dental bacteria in the pathogenesis of IE are far from elucidation to date. How do a few microorganisms survive host defenses or escape from antibiotic attacking to seed target organs and cause distant infections? Why are Gram-positive bacteria more frequently detected than Gram-negative bacteria in IE? Cell wall-deficient bacteria (CWDB) were traditionally defined as bacteria with altered morphology and consistent with damaged or absent cell wall structures identified by EM. A number of case reports and laboratory studies suggest that CWDB may be found in the peripheral blood of patients with IE, and may also be demonstrated in vegetations on the valves of patients with IE. CWDB, in vitro, are resistant to antibiotics that act on cell wall biosynthesis. Recent studies indicate that the Streptococcus mutans (S. mutans) strains, the major cariogenic bacterium, isolated from the infected valve were deficient in some wall-associated proteins which are main cariogenic virulence of S. mutans, and the deficient stains exhibited less susceptible to antibiotics that act on cell wall biosynthesis. Further, the cloned deficient mutans were less susceptible to phagocytosis by human polymorphonuclear leukocytes but to possess higher platelet aggregation properties than their parent strains. As outlined above, we hypothesize that defect of cell wall construction may shield oral bacteria's survival in bloodstream and cause IE.

Molecular analyses of bacterial DNA in extirpated heart valves from patients with infective endocarditis

BACKGROUND/AIMS

Infective endocarditis (IE) is caused by a microbial infection of the endothelial surface of the heart. Although blood culture examinations are commonly used to determine the associated bacterial species, molecular techniques, which enable rapid identification of targeted bacterial species, have recently been applied in clinical cases.

METHODS

Nine heart valve specimens from IE patients (six subacute cases and three acute cases) were extirpated and collected, then bacterial DNA was extracted. Bacterial species in the specimens were determined by two different molecular methods and the results were compared with those from a conventional blood culture technique. In addition, a comparison between the two molecular methods was carried out using known numbers of six streptococcal species.

RESULTS

The conventional blood culture method revealed the bacterial species in eight cases, while one was found to be negative. Multiple species were identified in most of the cases by both molecular methods; however, those specified by one method were not always consistent with those specified by the other. Furthermore, the species determined by the blood culture technique were not always identified by the molecular methods. We also found that the two molecular methods used in the present study were extremely sensitive to detect from 1 to 100 cells of individual oral streptococcal species.

CONCLUSION

Our results suggest that species specified by molecular methods may have disseminated incidentally into the bloodstream, so interpretation of such results should be carefully undertaken in clinical situations.

Detection of oral bacteria in cardiovascular specimens

BACKGROUND/AIMS

Oral bacteria, including cariogenic and periodontal pathogens, are thought to be etiological factors in the development of cardiovascular diseases. To define this relationship, we analyzed the distribution of oral bacterial species in cardiovascular specimens.

METHOD

Following acceptance into the study, 203 consecutive patients were analyzed, from whom 82 aortic valve specimens, 35 mitral valve specimens, and 86 aortic aneurysmal wall specimens, of which 16 contained aneurysmal thrombus tissues, were obtained. In addition, a total of 58 dental plaque specimens were collected from the same group of patients who underwent heart valve replacement or removal of aortic aneurysms. Bacterial DNA was extracted from both cardiovascular tissues and dental plaque in those cases and then species-specific polymerase chain reaction assays were used to analyze the occurrences of six oral streptococcal and six periodontal bacterial species.

RESULTS

Streptococcus mutans was the most frequently detected species in the cardiovascular specimens, followed by Aggregatibacter actinomycetemcomitans. As for dental plaque specimens from patients who underwent cardiovascular operations, most of the tested periodontitis-related species as well as oral streptococci were detected at high frequencies. Furthermore, the positive rate of S. mutans in cardiovascular specimens from patients whose dental plaque specimens were also positive for S. mutans was 78%, which was significantly higher than any other tested species when the same analysis was performed.

CONCLUSION

Our results suggest that specific oral bacterial species, such as S. mutans and A. actinomycetemcomitans, are related to bacteremia and may be etiologic factors for the development of cardiovascular diseases.

New British and American guidelines for the antibiotic prophylaxis of infective endocarditis: do the changes make sense? A critical review

PURPOSE OF REVIEW

The British Society for Antimicrobial Chemotherapy and the American Heart Association have radically revised their guidelines for the antibiotic prophylaxis of endocarditis. This review discusses the evidence behind the most controversial changes and considers possible future developments.

RECENT FINDINGS

The new guidelines emphasize good oral hygiene for preventing viridans streptococcal endocarditis. Antibiotic prophylaxis for dental procedures is only recommended for patients with the highest-risk cardiac conditions. American Heart Association guidelines no longer recommend prophylaxis for urological and gastrointestinal procedures.

SUMMARY

While only up to 6% of endocarditis cases may be prevented by antibiotic prophylaxis there is controversy as to what to recommend for the individual cardiac patient undergoing a given procedure. The new guidelines about dental prophylaxis are based on epidemiological studies that failed to include sufficient subjects undergoing specific interventions. When considering viridans streptococcal rather than total bacteraemia rates, asserting that the prevalence of bacteraemia after invasive dental procedures is similar to that after toothbrushing may be incorrect. The British Society for Antimicrobial Chemotherapy report probably overestimates the risk of fatal anaphylaxis after an oral dose of amoxicillin. In contrast, the American Heart Association guidelines comment on the absence of any reports of fatal anaphylaxis associated with the antibiotic prophylaxis of endocarditis.

Canine Bacterial Endocarditis: A Review

Bacterial endocarditis is a disease of primarily middle-aged to older, large-breed dogs that is associated with high morbidity and mortality. It presents many challenges with respect to diagnosis and effective treatment. This paper reviews the pathogenesis, clinical presentation, progression, methods of diagnosis, and treatment of bacterial endocarditis in dogs. Methods for proper diagnosis, including echocardiographic findings and blood culture techniques, and recommendations for effective antimicrobial therapy are also provided.

Repeated bacteraemia caused by Streptococcus mutans in a patient with Sjogren's syndrome

Streptococcus mutans, considered to be a pathogen for dental caries, is known to cause bacteraemia and infective endocarditis. Herein, an unusual case of repeated bacteraemia caused by S. mutans identified in a 71-year-old male is described. The patient visited Itami City Hospital with the major complaint of a fever, and a subsequent clinical examination led to a diagnosis of possible infective endocarditis without specific vegetation formation around the heart valve. A bacteriological examination of blood taken at the first visit showed the presence of S. mutans. Antimicrobial treatment was provided, which successfully eliminated the pathogenic bacteria from the blood. However, the patient returned and was hospitalized twice more with a recurrent fever, and S. mutans was again detected. Analyses of the biological properties of the S. mutans isolates showed that they possessed cariogenic properties and had a low susceptibility to phagocytosis by human polymorphonuclear leukocytes. Since the patient had Sjögren's syndrome, in which a reduction of saliva secretion is a characteristic feature, a great number of dental caries lesions were identified. The findings indicated that S. mutans present in those dental caries lesions caused repeated bacteraemia in this case.

Streptococcus mutans clonal variation revealed by multilocus sequence typing

Streptococcus mutans is the major pathogen of dental caries, a biofilm-dependent infectious disease, and occasionally causes infective endocarditis. S. mutans strains have been classified into four serotypes (c, e, f, and k). However, little is known about the S. mutans population, including the clonal relationships among strains of S. mutans, in relation to the particular clones that cause systemic diseases. To address this issue, we have developed a multilocus sequence typing (MLST) scheme for S. mutans. Eight housekeeping gene fragments were sequenced from each of 102 S. mutans isolates collected from the four serotypes in Japan and Finland. Between 14 and 23 alleles per locus were identified, allowing us theoretically to distinguish more than 1.2 x 10(10) sequence types. We identified 92 sequence types in these 102 isolates, indicating that S. mutans contains a diverse population. Whereas serotype c strains were widely distributed in the dendrogram, serotype e, f, and k strains were differentiated into clonal complexes. Therefore, we conclude that the ancestral strain of S. mutans was serotype c. No geographic specificity was identified. However, the distribution of the collagen-binding protein gene (cnm) and direct evidence of mother-to-child transmission were clearly evident. In conclusion, the superior discriminatory capacity of this MLST scheme for S. mutans may have important practical implications.

The impact of clinical audit on antibiotic prescribing in general dental practice

OBJECTIVE

To reduce the number of antibiotics inappropriately prescribed by general dental practitioners, and to increase overall prescription accuracy.

DESIGN

A prospective clinical audit carried out between September and March of 2002-3 and 2003-4.

SETTING

General dental practices in Eastern England.

SUBJECTS AND METHODS

The pre-audit antibiotic prescribing practices of 212 general dental practitioners were recorded over an initial six week period. On each occasion this included which antibiotic had been chosen, together with its dose, frequency and duration, as well as the clinical condition and reason for which the prescription had been raised. When related to prophylaxis, the patient's medical history was also noted. Following education on contemporary prescribing guidelines, presentations which illustrated the practitioners' previous errors, and the agreement of standards to be achieved, the process was repeated for another six weeks, and the results compared.

RESULTS

In the pre-audit period, 2,951 antibiotic prescriptions were issued, and during the audit this was reduced by 43.6% to 1,665. The majority were for therapeutic reasons, with only 10.5% and 13.6% for medical prophylaxis during the pre-audit and audit periods respectively. Over both periods, amoxicillin and metronidazole were the two most commonly prescribed antimicrobials (63.4% and 21.2% respectively). In the pre-audit period, only 43% of all prescriptions were error free in dose, frequency, and/or duration of use, but this rose significantly to 78% during the audit. Equally, using contemporary published guidelines, out of all the prescriptions made in the pre-audit period, only 29.2% were deemed to be justified, as compared to 48.5% during the audit.

CONCLUSIONS

Clinical audit, in conjunction with education, and prescribing guidelines can favourably change antibiotic prescribing patterns among general dental practitioners.

Detection of cariogenic Streptococcus mutans in extirpated heart valve and atheromatous plaque specimens

The involvement of oral bacteria in the pathogenesis of cardiovascular diseases has been the focus of attention in many studies, and several periodontal pathogens have been detected in diseased cardiovascular lesions, suggesting relationships between oral microorganisms and cardiovascular diseases. However, no information is available regarding the involvement of cariogenic pathogens such as Streptococcus mutans. The presence of oral streptococcal species and periodontitis-related bacteria in 35 heart valve and 27 atheromatous plaque clinical specimens, as well as 32 dental plaque specimens from the same subjects, was analyzed using a PCR method. Furthermore, broad-range PCR with DNA sequencing analysis was employed to identify the bacterial species in those samples. Streptococcus mutans was frequently detected in the heart valve (69%) and atheromatous plaque (74%) specimens, while other bacterial species, including those related to periodontitis, were detected with much lower frequencies. The bacterial composition in cardiovascular tissues was found to be markedly distinct from that in dental plaque, with only a limited number of species, including S. mutans, in the cardiovascular regions shown to have possibly originated from the oral cavity. Semiquantitative assay results revealed that S. mutans was detected in significant quantities in the heart valve (40%) and atheromatous plaque (48%) specimens, whereas the quantities of all other tested bacterial species, including several related to periodontitis, were negligible in the cardiovascular samples. These results indicate that S. mutans is a possible causative agent of cardiovascular disease.