Acute rheumatic fever and rheumatic heart disease

Guidelines for the management of common congenital heart diseases in India: A consensus statement on indications and timing of intervention

INTRODUCTION

A number of guidelines are available for management of congenital heart diseases from infancy to adult life. However, these guidelines are for patients living in high-income countries. Separate guidelines, applicable to Indian children, are required when recommending an intervention for congenital heart diseases, as often these patients present late in the course of the disease and may have co-existing morbidities and malnutrition.

PROCESS

Guidelines emerged following expert deliberations at the National Consensus Meeting on Management of Congenital Heart Diseases in India, held on the 10th and 11th of August, 2018 at the All India Institute of Medical Sciences.

OBJECTIVES

The aim of the study was to frame evidence-based guidelines for (i) indications and optimal timing of intervention in common congenital heart diseases and (ii) follow-up protocols for patients who have undergone cardiac surgery/catheter interventions for congenital heart diseases.

RECOMMENDATIONS

Evidence-based recommendations are provided for indications and timing of intervention in common congenital heart diseases, including left-to-right shunts, obstructive lesions, and cyanotic congenital heart diseases. In addition, protocols for follow-up of postsurgical patients are also described.

A cluster of acute rheumatic fever cases among Aboriginal Australians in a remote community with high baseline incidence

OBJECTIVES

We report a cluster of acute rheumatic fever (ARF) cases and the public health response in a high-burden Australian setting.

METHODS

The public health unit was notified of an increase in ARF cases in a remote Australian Aboriginal community. A multi-disciplinary group coordinated the response. Household contacts were screened for ARF or group A Streptococcus (GAS) infection by questionnaire and swab collection, offered an echocardiogram if aged 5-20 years, and intramuscular benzathine benzylpenicillin if aged over one year or if less than one year with impetigo.

RESULTS

Fifteen definite and seven probable ARF cases were diagnosed in the community in July-December 2014 (all-age incidence of definite ARF: 1,473/100,000). The public health response identified two additional cases of ARF. A total of 81 contacts were screened; GAS was detected in 3/76 (4%) throat swabs and 11/24 (46%) skin swabs. Molecular typing revealed high GAS strain diversity.

CONCLUSIONS

The incidence of ARF during this cluster was very high. Carriage and infection with GAS was observed, but no outbreak strain identified. Implications for public health: A national public health guideline has since been developed that includes advice on the investigation of an ARF outbreak/cluster. Sustained efforts with strong community engagement are required to tackle high ARF rates.

Rheumatic heart disease in the modern era: recent developments and current challenges

Rheumatic heart disease (RHD) remains a major cause of preventable death and disability in children and young adults. Despite significant advances in medical technology and increased understanding of disease mechanisms, RHD continues to be a serious public health problem throughout the world, especially in low- and middle-income countries. Echocardiographic screening has played a key role in improving the accuracy of diagnosing RHD and has highlighted the disease burden. Most affected patients present with severe valve disease and limited access to life-saving cardiac surgery or percutaneous valve intervention, contributing to increased mortality and other complications. Although understanding of disease pathogenesis has advanced in recent years, key questions remain to be addressed. Preventing or providing early treatment for streptococcal infections is the most important step in reducing the burden of this disease.

The World Heart Federation criteria raise the threshold of diagnosis for mild rheumatic heart disease: Three reviewers are better than one

BACKGROUND

The World Heart Federation (WHF) criteria, published in 2012, provided an evidence-based guideline for the minimal diagnosis of echocardiographically-detected RHD. Primary aim of the study was to determine whether use of the WHF criteria altered the threshold for the diagnosis of echocardiographically-detected RHD compared with the previous WHO/NIH criteria. A secondary aim was to explore the utility of a three reviewer reporting system compared to a single or two reviewer reporting structure.

METHODS

144 de-identified echocardiograms (RHD, congenital valvar abnormality, physiological valvar regurgitation) were independently reported using the WHF criteria by two reviewers blinded to the previous WHO/NIH diagnosis. If there was discordance between the two reviewers, a third cardiologist independently performed a tie-breaker review.

RESULTS

There was a 21% reduction of cases classified as RHD using the WHF criteria compared to the modified WHO/NIH criteria (68 cases compared to 86, p = 0.04). There was a 60% consensus across the different diagnostic categories with 2 reviewers, 89% majority agreement with 3 reviewers. 11% required an open label discussion. There was moderate agreement between 2 reviewers for any RHD, kappa 0.57 (CI 0.44-0.70), with no significant difference in agreement between the different categories.

CONCLUSION

The WHF criteria have raised the threshold for the diagnosis of RHD compared to the WHO/NIH criteria. However, inter-reporter variability of the WHF criteria is high. A three reviewer system is likely more accurate than a single or two reporter system for the diagnosis of mild RHD. This has resource implications for echocardiographic screening programmes.

Integrated analysis of population genomics, transcriptomics and virulence provides novel insights into Streptococcus pyogenes pathogenesis

Streptococcus pyogenes causes 700 million human infections annually worldwide, yet, despite a century of intensive effort, there is no licensed vaccine against this bacterium. Although a number of large-scale genomic studies of bacterial pathogens have been published, the relationships among the genome, transcriptome, and virulence in large bacterial populations remain poorly understood. We sequenced the genomes of 2,101 emm28 S. pyogenes invasive strains, from which we selected 492 phylogenetically diverse strains for transcriptome analysis and 50 strains for virulence assessment. Data integration provided a novel understanding of the virulence mechanisms of this model organism. Genome-wide association study, expression quantitative trait loci analysis, machine learning, and isogenic mutant strains identified and confirmed a one-nucleotide indel in an intergenic region that significantly alters global transcript profiles and ultimately virulence. The integrative strategy that we used is generally applicable to any microbe and may lead to new therapeutics for many human pathogens.

Two-year evolution of latent rheumatic heart disease in Malawi

BACKGROUND

In asymptomatic children, screening echocardiography has been used to attempt to diagnose rheumatic heart disease (RHD) at an early stage (latent RHD). World Heart Federation guidelines have standardized categorization of "definite," "borderline," or no RHD by echo findings. The progression of RHD diagnosed through echo screening is not known. In 2014, we screened 1450 schoolchildren in Malawi.

OBJECTIVE

Our objective was to evaluate 2-year RHD evolution among those diagnosed through screening.

METHODS

Two-year follow-up echocardiograms of those diagnosed with latent RHD were read by a primary, secondary, then third reader if there was disagreement. Progression or regression of both definite and borderline groups were tabulated. Penicillin adherence, age, gender, number in home, and household income were compared between those with definite RHD who regressed to borderline and those that stayed definite. We utilized the local system used to track HIV defaulters in order to bring participants back into care. Comparisons were made using Fisher's exact and Wilcoxon rank-sum tests.

RESULTS

Of the 39 with borderline RHD, 1 was lost to follow-up (2.6%), 1 progressed to definite (2.6%), 19 remained borderline (48.7%), 17 (43.6%) regressed to normal, and 1 was reclassified as mitral valve prolapse (2.6%). Of the 11 with definite RHD, 6 (54.5%) remained definite, 4 regressed to borderline (36.4%), and 1 regressed to normal (9.1%). Two of 11 with definite RHD had penicillin adherence above 80% for the 2-year follow-up period. There were no differences in adherence, gender, age, household income, or number in household between those with definite RHD that regressed to borderline and those who did not (P > .19).

CONCLUSIONS

Borderlines had a very low progression rate to definite RHD. A strength of our study was a high retention rate (98%). Longer follow-up is needed to determine expected disease evolution.

T cell subsets: an integral component in pathogenesis of rheumatic heart disease

Acute rheumatic fever (ARF) is a consequence of pharyngeal infection of group A streptococcal (GAS) infection. Carditis is the most common manifestation of ARF which occurs in 30-45% of the susceptible individuals. Overlooked ARF cases might further progress towards rheumatic heart disease (RHD) in susceptible individuals, which ultimately leads to permanent heart valve damage. Molecular mimicry between streptococcal antigens and human proteins is the most widely accepted theory to describe the pathogenesis of RHD. In the recent past, various subsets of T cells have been reported to play an imperative role in the pathogenesis of RHD. Alterations in various T cell subsets, viz. Th1, Th2, Th17, and Treg cells, and their signature cytokines influence the immune responses and are associated with pathogenesis of RHD. Association of other T cell subsets (Th3, Th9, Th22, and T_FH) is not defined in context of RHD. Several investigations have confirmed the up-regulation of adhesion molecules and thus infiltration of T cells into the heart tissues. T cells secrete both Th type 1 and type 2 cytokines and these auto-reactive T cells play a key role in progression of heart valve damage. In this review, we are going to discuss about the role of T cell subsets and their corresponding cytokines in the pathogenesis of RHD.

Focus on Cardiologic Findings in 30 Children With PANS/PANDAS: An Italian Single-Center Observational Study

Objective: Cardiac involvement in PANS has not been clarified relying on the scientific literature available until today. It is known that streptococcal infections play a role in the etiology of a great number of diseases including Sydenham chorea and rheumatic fever, among others. Based on the suspected pathogenesis of PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) reported in the medical literature, we decided to investigate the cardiologic involvement in children with a recent PANS/PANDAS diagnosis. Methods: The study population satisfies PANS (1) and PANDAS (2) criteria of diagnoses. Cardiologic assessment was performed through clinical examination, electrocardiography, and echocardiography. Results: In the selected pediatric population, a significant number of children presented mitral valve involvement, systolic murmurs and electrocardiographic abnormalities. High ASLOT levels did not seem to be associated to a cardiac involvement. Conclusions: Often PANS is difficult to diagnose because it is little known by physicians and most of the cardiologic findings described in this study are common among the healthy pediatric population. Also, ASLOT levels seems not to be predictive of cardiac involvement. Furthermore, the existence of PANDAS as a clinical entity is associated with a group of anti-neuronal autoantibodies found in Sydenham chorea is still controversial. We recommend a complete cardiologic evaluation in those children who meet the PANS/PANDAS diagnostic criteria.

Associations between ambient temperature and daily hospital admissions for rheumatic heart disease in Shanghai, China

Rheumatic heart disease (RHD) remains a serious public health burden in developing countries. We conducted a time-series study to explore the association between ambient temperature and daily hospital admissions for RHD in Shanghai, China. We collected data on daily hospital admissions for RHD from 2013 to 2015 from the database of Shanghai Health Insurance System. We applied the generalized additive models together with the distributed lag nonlinear model to estimate the association between temperature and RHD hospital admissions after controlling for relative humidity, time trend, day of the week, and holidays. Stratification analyses by age and gender were performed to evaluate their potential effect modification. A total of 4178 cases of RHD hospitalizations were identified over the study period. There were almost linear, positive, and significant associations between daily mean temperature and RHD hospital admissions with higher risks at hotter days. Compared to reference temperature (0 °C), the cumulative risks of moderate heat (the 90th percentile of temperature, 28.0 °C) and extreme heat (the 99th percentile of temperature, 33.5 °C) over lags 0-5 days were 2.55 (95% confidence interval 1.14, 5.73) and 3.22 (95% confidence interval 1.36, 7.61), respectively. These associations were significantly stronger in older people than in younger people. This study indicated larger risks of RHD hospital admissions associated with higher temperature, especially in older people. Our findings provided first-hand epidemiological evidence regarding the effects of ambient temperature on RHD incidence.

Lessons learned in the development of sustained release penicillin drug delivery systems for the prophylactic treatment of rheumatic heart disease (RHD)

The current prophylactic treatment to prevent rheumatic heart disease requires four-weekly intramuscular injection of a suspension of the poorly soluble benzathine salt form of penicillin G (BPG) often for more than 10 years. In seeking to reduce the frequency of administration to improve adherence, biodegradable polymer matrices have been investigated. Poly(lactide-co-glycolide) (PLGA)-based in situ forming precursor systems containing N-methyl-2-pyrrolidone as solvent and PLGA-based monolithic implants for surgical implantation containing BPG were developed. Long-term release studies indicated low and plateaued release of penicillin G, but continual favourable release profiles for the benzathine counterion, indicating degradation of the polymer and generation of acidic microenvironment being detrimental to penicillin stability. In order to avoid the issue of the acidic product, poly(caprolactone)(PCL) implants were also investigated, with favourable penicillin G release behaviour being achieved, and slow release over 180 days. However, when taking into account the mass of polymer, and the total dose of drug calculated from literature pharmacokinetic parameters for penicillin G, we concluded that an implant size of over 7 g would still be required. This may preclude clinical deployment of a polymer matrix type delivery system for this indication in children and adolescents. Therefore, we have learned that biodegradable PLGA-type systems are not suitable for development of sustained release BPG treatments and that although the PCL system provides favourable release behaviour, the total size of the implant may still present a hurdle for future development.

Heart Disease in Children

The pediatric cardiology field has developed rapidly over the past few decades. More children than ever born with congenital heart disease (CHD) are growing into adulthood. Primary care providers play a key role in diagnosis, management, and referral of children with CHD because many common cardiac complaints (eg, feeding intolerance, cyanosis, chest pain, palpitations, and syncope) are first addressed in the primary care setting. The spectrum of heart disease in children ranges from common complaints to complex single-ventricle physiology, acute myocarditis, and heart transplantation. This article reviews the pathophysiology and management of the most frequent cardiac conditions encountered in primary care.

The fall and rise of Group A Streptococcus diseases

Streptococcus pyogenes (or Group A Streptococcus, GAS) is a Gram-positive human pathogen responsible for a diverse array of superficial, invasive and immune-related diseases. GAS infections have historically been diseases of poverty and overcrowding, and remain a significant problem in the developing world and in disadvantaged populations within developed countries. With improved living conditions and access to antibiotics, the rates of GAS diseases in developed societies have gradually declined during the 20th century. However, genetic changes in circulating GAS strains and/or changes in host susceptibility to infection can lead to dramatic increases in the rates of specific diseases. No situations exemplify this more than the global upsurge of invasive GAS disease that originated in the 1980s and the regional increases in scarlet fever in north-east Asia and the UK. In each case, increased disease rates have been associated with the emergence of new GAS strains with increased disease-causing capability. Global surveillance for new GAS strains with increased virulence is important and determining why certain populations suddenly become susceptible to circulating strains remains a research priority. Here, we overview the changing epidemiology of GAS infections and the genetic alterations that accompany the emergence of GAS strains with increased capacity to cause disease.

Molecular mimicry: An explanation for autoimmune diseases and infertility

Microorganisms execute an enthralling range of adjustments to survive in the host. Among the various strategies employed by microorganisms to surmount the host immune response, the phenomenon of molecular mimicry empowers the microorganisms to manoeuvre host physiology and cellular functions for their own advantage by mimicking the host proteins and initiating autoimmunity. This phenomena, by and large, has been studied in context of autoimmune diseases; however, its implications have also been reported in infertility. Hence, in this article, we provide a review of the various instances of molecular mimicry initiated by bacteria, parasites and viruses in the world of autoimmune diseases and infertility.

Acute rheumatic fever

Acute rheumatic fever is caused by an autoimmune response to throat infection with Streptococcus pyogenes. Cardiac involvement during acute rheumatic fever can result in rheumatic heart disease, which can cause heart failure and premature mortality. Poverty and household overcrowding are associated with an increased prevalence of acute rheumatic fever and rheumatic heart disease, both of which remain a public health problem in many low-income countries. Control efforts are hampered by the scarcity of accurate data on disease burden, and effective approaches to diagnosis, prevention, and treatment. The diagnosis of acute rheumatic fever is entirely clinical, without any laboratory gold standard, and no treatments have been shown to reduce progression to rheumatic heart disease. Prevention mainly relies on the prompt recognition and treatment of streptococcal pharyngitis, and avoidance of recurrent infection using long-term antibiotics. But evidence for the effectiveness of either approach is not strong. High-quality research is urgently needed to guide efforts to reduce acute rheumatic fever incidence and prevent progression to rheumatic heart disease.

Association of IL17 and IL23R gene polymorphisms with rheumatic heart disease in South Indian population

BACKGROUND

IL-23/Th17 signaling pathway plays a crucial role in the cell-mediated immune response against bacterial infections and also in the pathogenesis of inflammatory and autoimmune diseases. Recent studies indicate that Th17 cell-associated cytokines are involved in the progression and maintenance of valvular lesions in rheumatic heart disease (RHD). Variants in the genes of cytokines that are potentially involved in Th17 response may influence interindividual differences in their expression levels, thereby contributing to the pathogenesis of immune-mediated diseases such as RHD.

OBJECTIVE

The aim of the study is to investigate the association of IL17A, IL17F, and IL23R gene variants with the risk perception of RHD.

METHODS

A total of 225 individuals (99 RHD patients and 126 healthy siblings) were recruited for the study. The IL17A (rs2275913), IL17F (rs763780), and IL23R (rs10889677) polymorphisms were determined by polymerase chain reaction restriction fragment length polymorphisms and amplification-refractory mutation system-polymerase chain reaction methods, respectively.

RESULTS

The frequency of IL17A (rs2275913) A/A genotype was significantly high in pooled RHD patients (odds ratio [OR] = 2.76; p_c = 0.021), rheumatic fever (RF) patients (OR = 14.5; p_c = 0.0001), and mitral valvular lesions patients (OR = 2.74; p_c = 0.039) when compared to healthy siblings. However, the IL17F (rs763780) and IL23R (rs10889677) polymorphisms did not show any association with RHD.

CONCLUSIONS

The results suggest that IL17A (rs2275913) polymorphism is associated with the development of RF/RHD in South Indian population. Further studies are required to substantiate the association of these genes with the disease risk.

Evaluation of safety and immunogenicity of a group A streptococcus vaccine candidate (MJ8VAX) in a randomized clinical trial

BACKGROUND

Group A streptococcus (GAS) is a serious human pathogen that affects people of different ages and socio-economic levels. Although vaccination is potentially one of the most effective methods to control GAS infection and its sequelae, few prototype vaccines have been investigated in humans. In this study, we report the safety and immunogenicity of a novel acetylated peptide-protein conjugate vaccine candidate MJ8VAX (J8-DT), when delivered intramuscularly to healthy adults.

METHODS

A randomized, double-blinded, controlled Phase I clinical trial was conducted in 10 healthy adult participants. Participants were randomized 4:1 to receive the vaccine candidate (N = 8) or placebo (N = 2). A single dose of the vaccine candidate (MJ8VAX), contained 50 μg of peptide conjugate (J8-DT) adsorbed onto aluminium hydroxide and re-suspended in PBS in a total volume of 0.5 mL. Safety of the vaccine candidate was assessed by monitoring local and systemic adverse reactions following intramuscular administration. The immunogenicity of the vaccine was assessed by measuring the levels of peptide (anti-J8) and toxoid carrier (anti-DT)-specific antibodies in serum samples.

RESULTS

No serious adverse events were reported over 12 months of study. A total of 13 adverse events (AEs) were recorded, two of which were assessed to be associated with the vaccine. Both were mild in severity. No local reactogenicity was recorded in any of the participants. MJ8VAX was shown to be immunogenic, with increase in vaccine-specific antibodies in the participants who received the vaccine. The maximum level of vaccine-specific antibodies was detected at 28 days post immunization. The level of these antibodies decreased with time during follow-up. Participants who received the vaccine also had a corresponding increase in anti-DT serum antibodies.

CONCLUSIONS

Intramuscular administration of MJ8VAX was demonstrated to be safe and immunogenic. The presence of DT in the vaccine formulation resulted in a boost in the level of anti-DT antibodies.

TRIAL REGISTRATION

ACTRN12613000030774.

A programme to increase appropriate usage of benzathine penicillin for management of streptococcal pharyngitis and rheumatic heart disease in Zambia

Rheumatic heart disease is highly prevalent and associated with substantial morbidity and mortality in many resource-poor areas of the world, including sub-Saharan Africa. Primary and secondary prophylaxis with penicillin has been shown to significantly improve outcomes and is recognised to be the standard of care, with intra-muscular benzathine penicillin G recommended as the preferred agent by many technical experts. However, ensuring compliance with therapy has proven to be challenging. As part of a public-private partnership initiative in Zambia, we conducted an educational and access-to-medicine programme aimed at increasing appropriate use of benzathine penicillin for the prevention and management of rheumatic heart disease, according to national guidelines. The programme was informed early on by identification of potential barriers to the administration of injectable penicillin, which included concern by health workers about allergic events. We describe this programme and report initial signs of success, as indicated by increased use of benzathine penicillin. We propose that a similar approach may have benefits in rheumatic heart disease programmes in other endemic regions.

Signaling by a Conserved Quorum Sensing Pathway Contributes to Growth Ex Vivo and Oropharyngeal Colonization of Human Pathogen Group A Streptococcus

Bacterial virulence factor production is a highly coordinated process. The temporal pattern of bacterial gene expression varies in different host anatomic sites to overcome niche-specific challenges. The human pathogen group A streptococcus (GAS) produces a potent secreted protease, SpeB, that is crucial for pathogenesis. Recently, we discovered that a quorum sensing pathway comprised of a leaderless short peptide, SpeB-inducing peptide (SIP), and a cytosolic global regulator, RopB, controls speB expression in concert with bacterial population density. The SIP signaling pathway is active in vivo and contributes significantly to GAS invasive infections. In the current study, we investigated the role of the SIP signaling pathway in GAS-host interactions during oropharyngeal colonization. The SIP signaling pathway is functional during growth ex vivo in human saliva. SIP-mediated speB expression plays a crucial role in GAS colonization of the mouse oropharynx. GAS employs a distinct pattern of SpeB production during growth ex vivo in saliva that includes a transient burst of speB expression during early stages of growth coupled with sustained levels of secreted SpeB protein. SpeB production aids GAS survival by degrading LL37, an abundant human antimicrobial peptide. We found that SIP signaling occurs during growth in human blood ex vivo. Moreover, the SIP signaling pathway is critical for GAS survival in blood. SIP-dependent speB regulation is functional in strains of diverse emm types, indicating that SIP signaling is a conserved virulence regulatory mechanism. Our discoveries have implications for future translational studies.

Psoriasis patients demonstrate HLA-Cw*06:02 allele dosage-dependent T cell proliferation when treated with hair follicle-derived keratin 17 protein

It is broadly accepted that psoriasis is an immune-mediated disease with a heritable component, but it is not clear what causes inflammation in the skin. Previous research suggests that fragments of the keratin 17 (K17) protein, which are constitutively expressed in hair follicles, could act as autoantigens. In this study, we synthesized the K17 protein from mRNA derived from hair follicles and tested whether it elicited T cell responses depending on the patient genotype at the major susceptibility locus HLA-Cw*06:02. We treated peripheral blood-derived cells with the K17 protein and its short fragments to assess the T cell proliferation response using flow cytometry. Our analyses show a significantly stronger increase in cell proliferation among patients but not in healthy controls. We then examined whether the variation in T cell proliferation correlated with the patient HLA-Cw*06:02 risk genotype. Considering the affected status and patient genotype as two independent predictors, we fitted a linear model and showed that the HLA-Cw*06:02 allele dosage strongly predicted the T cell response. Our study findings suggest that the K17 protein likely acts as an autoantigen in psoriasis and that patients’ risk genotype is strongly correlated with the magnitude of the response to this putative autoantigen.

Differential binding of antibodies in PANDAS patients to cholinergic interneurons in the striatum

Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus, or PANDAS, is a syndrome of acute childhood onset of obsessive-compulsive disorder and other neuropsychiatric symptoms in the aftermath of an infection with Group A beta-hemolytic Streptococcus (GABHS). Its pathophysiology remains unclear. PANDAS has been proposed to result from cross-reactivity of antibodies raised against GABHS with brain antigens, but the targets of these antibodies are unclear and may be heterogeneous. We developed an in vivo assay in mice to characterize the cellular targets of antibodies in serum from individuals with PANDAS. We focus on striatal interneurons, which have been implicated in the pathogenesis of tic disorders. Sera from children with well-characterized PANDAS (n = 5) from a previously described clinical trial (NCT01281969), and matched controls, were infused into the striatum of mice; antibody binding to interneurons was characterized using immunofluorescence and confocal microscopy. Antibodies from children with PANDAS bound to ∼80% of cholinergic interneurons, significantly higher than the <50% binding seen with matched healthy controls. There was no elevated binding to two different populations of GABAergic interneurons (PV and nNOS-positive), confirming the specificity of this phenomenon. Elevated binding to cholinergic interneurons resolved in parallel with symptom improvement after treatment with intravenous immunoglobulin. Antibody-mediated dysregulation of striatal cholinergic interneurons may be a locus of pathology in PANDAS. Future clarification of the functional consequences of this specific binding may identify new opportunities for intervention in children with this condition.

The clinical characteristics of adults with rheumatic heart disease in Yangon, Myanmar: An observational study

BACKGROUND

Rheumatic heart disease (RHD) is a major cause of premature death in low and middle-income countries. The greatest barrier to RHD control is neglect of the disease in national health policies and a lack of prevalence data that might inform control efforts. Myanmar is making remarkable progress against many infectious diseases, but there are almost no data to define the clinical burden of RHD in the country. This prospective audit was performed in an adult medical ward of a tertiary-referral hospital in Yangon, to gain an insight into the prevalence of RHD in Myanmar.

PRINCIPAL FINDINGS

All patients admitted to the ward between May 1, 2016 and April 30, 2017 were eligible for enrolment. RHD was confirmed in 96 patients who were admitted on 134 occasions, representing 1.1% of the 12,172 adult medical admissions during the study period. This compared with 410 (3.4%) admissions with HIV and 14 (0.1%) with malaria. Patients with RHD had a median age of 44 years (interquartile range: 35-59); 70 (73%) were female. Only one patient had ever had surgery despite 79 (82%) meeting criteria for intervention; 54 (56%) patients were not receiving any regular clinician review. Prior to hospitalisation only 18 (19%) patients were receiving regular penicillin. Only 8 (19%) of the 42 women <50 years were using contraception. Of 49 patients who had been hospitalised previously, 22 (45%) were receiving no regular therapy. During the study three (3.1%) patients died, and 28 (29%) were lost to follow-up. Of the 65 (68%) alive and retained in care, 21 (32%) were still experiencing moderate-severe RHD-related symptoms at the study's end.

CONCLUSIONS

There is a significant and unmet clinical burden of RHD in Myanmar. A national RHD programme would improve patient care, reducing morbidity and mortality from this preventable disease.

Pregnancy Outcomes in Women With Rheumatic Mitral Valve Disease

Background:

Cardiac disease is 1 of the major causes of maternal mortality. We studied pregnancy outcomes in women with rheumatic mitral valve disease.

Methods:

The Registry of Pregnancy and Cardiac Disease is an international prospective registry, and consecutive pregnant women with cardiac disease were included. Pregnancy outcomes in all women with rheumatic mitral valve disease and no prepregnancy valve replacement is described in the present study (n=390). A maternal cardiac event was defined as cardiac death, arrhythmia requiring treatment, heart failure, thromboembolic event, aortic dissection, endocarditis, acute coronary syndrome, and hospitalization for other cardiac reasons or cardiac intervention. Associations between patient characteristics and cardiac outcomes were checked in a 3-level model (patient–center–country).

Results:

Most patients came from emerging countries (75%). Mitral stenosis (MS) with or without mitral regurgitation (MR) was present in 273 women, isolated MR in 117. The degree of MS was mild in 20.9%, moderate in 39.2%, severe in 19.8%, and severity not classified in the remainder. Maternal death during pregnancy occurred in 1 patient with severe MS. Hospital admission occurred in 23.1% of the women with MS, and the main reason was heart failure (mild MS 15.8%, moderate 23.4%, severe 48.1%; P <0.001). Heart failure occurred in 23.1% of patients with moderate or severe MR. An intervention during pregnancy was performed in 16 patients, 14 had percutaneous balloon mitral commissurotomy, and 2 had surgical valve replacement (1 for MS, 1 for MR). In multivariable modeling, prepregnancy New York Heart Association class >1 was an independent predictor of maternal cardiac events. Follow-up at 6 months postpartum was available for 53%, and 3 more patients died (1 with severe MS, 1 with moderate MS, 1 with moderate to severe MR).

Conclusions:

Although mortality was only 1.9% during pregnancy, ≈50% of the patients with severe rheumatic MS and 23% of those with significant MR developed heart failure during pregnancy. Prepregnancy counseling and considering mitral valve interventions in selected patients are important to prevent these complications.

Identification and Characterization of Serotype-Specific Variation in Group A Streptococcus Pilus Expression

Isolates of a given bacterial pathogen often display phenotypic variation, and this can negatively impact public health, for example, by reducing the efficacy of preventative measures. Here, we identify that the human pathogen group A Streptococcus (GAS; Streptococcus pyogenes) expresses pili on its cell surface in a serotype-specific manner. Specifically, we show that serotype M3 GAS isolates, which are nonrandomly associated with causing particularly severe and lethal invasive infections, produce negligible amounts of pili relative to serotype M1 and M49 isolates. Performance of an interserotype transcriptome comparison (serotype M1 versus serotype M3) was instrumental in this discovery. We also identified that the transcriptional regulator Nra positively regulates pilus expression in M3 GAS isolates and that the low level of pilus expression of these isolates correlates with a low level of nra transcription. Finally, we discovered that the phenotypic consequences of low levels of pilus expression by M3 GAS isolates are a reduced ability to adhere to host cells and an increased ability to survive and proliferate in human blood. We propose that an enhanced ability to survive in human blood, in part due to reduced pilus expression, is a contributing factor in the association of serotype M3 isolates with highly invasive infections. In conclusion, our data show that GAS isolates express pili in a serotype-dependent manner and may inform vaccine development, given that pilus proteins are being discussed as possible GAS vaccine antigens.

Acquired heart disease in low-income and middle-income countries

The burden of illness associated with acquired cardiac disease in children in low-income and middle-income countries (LMIC) is significant and may be equivalent to that of congenital heart disease. Rheumatic heart disease, endomyocardial fibrosis, cardiomyopathy (including HIV cardiomyopathy) and tuberculosis are the most important causes. All are associated with poverty with the neediest children having the least access to care. The associated mortality and morbidity is high. There is an urgent need to improve cardiac care in LMIC, particularly in sub-Saharan Africa and parts of Southeast Asia where the burden is highest.

A focussed single-view hand-held echocardiography protocol for the detection of rheumatic heart disease

BACKGROUND

Echocardiographic screening represents an opportunity for reduction in the global burden of rheumatic heart disease. A focussed single-view screening protocol could allow for the rapid training of healthcare providers and screening of patients.

OBJECTIVE

The aim of this study was to determine the sensitivity and specificity of a focussed single-view hand-held echocardiographic protocol for the diagnosis of rheumatic heart disease in children.

METHODS

A total of nine readers were divided into three reading groups; each interpreted 200 hand-held echocardiography studies retrospectively as screen-positive, if mitral regurgitation ⩾1.5 cm and/or any aortic insufficiency were observed, or screen-negative from a pooled study library. The performance of experts receiving focussed hand-held protocols, non-experts receiving focussed hand-held protocols, and experts receiving complete hand-held protocols were determined in comparison with consensus interpretations on fully functional echocardiography machines.

RESULTS

In all, 587 studies including 76 on definite rheumatic heart disease, 122 on borderline rheumatic heart disease, and 389 on normal cases were available for analysis. The focussed single-view protocol had a sensitivity of 81.1%, specificity of 75.5%, negative predictive value of 88.5%, and a positive predictive value of 63.2%; expert readers had higher specificity (86.1 versus 64.8%, p<0.01) but equal sensitivity. Sensitivity - experts, 96% and non-experts, 95% - and negative predictive value - experts, 99% and non-experts, 98% - were better for definite rheumatic heart disease. False-positive screening studies resulting from erroneous identification of mitral regurgitation and aortic insufficiency colour jets increased with shortened protocols and less experience (p<0.01).

CONCLUSION

Our data support a focussed screening protocol limited to parasternal long-axis images. This holds promise in making echocardiographic screening more practical in regions where rheumatic heart disease remains endemic.

Prevention and control of rheumatic heart disease: Overcoming core challenges in resource-poor environments

Rheumatic heart disease (RHD) has long receded as a significant threat to public health in high-income countries. In low-resource settings, however, the specter of RHD remains unabated, as exemplified by recent data from the Global Burden of Diseases Study. There are many complex reasons for this ongoing global disparity, including inadequate data on disease burden, challenges in effective advocacy, ongoing poverty and inequality, and weak health systems, most of which predominantly affect developing nations. In this review, we discuss how each of these acts as a core challenge in RHD prevention and control. We then examine key lessons learnt from successful control programs in the past and highlight resources that have been developed to help create strong national RHD control programs.

Prevalence and prognostic value of echocardiographic screening for rheumatic heart disease

Objective

Rheumatic heart disease (RHD) remains a major health problem in many low-income and middle-income countries. The use of echocardiographic imaging suggests that subclinical disease is far more widespread than previously appreciated, but little is known as to how these mild forms of RHD progress. We have determined the prevalence of subclinical RHD in a large group of schoolchildren in Aswan, Egypt and have evaluated its subsequent progression.

Methods

Echocardiographic screening was performed on 3062 randomly selected schoolchildren, aged 5–15 years, in Aswan, Egypt. Follow-up of children with a definite or borderline diagnosis of RHD was carried out 48–60 months later to determine how the valvular abnormalities altered and to evaluate the factors influencing progression.

Results

Sixty children were initially diagnosed with definite RHD (19.6 per 1000 children) and 35 with borderline disease (11.4 per 1000); most had mitral valve disease. Of the 72 children followed up progression was documented in 14 children (19.4%) and regression in 30 (41.7%) children. Boys had lower rates of progression while older children had lower rates of regression. Functional defects of the valve even in the presence of structural features were associated with lower rates of progression and higher rates of regression than structural changes.

Conclusions

RHD has a high prevalence in Egypt. Although a high proportion of the abnormalities originally detected persisted at follow-up, both progression and regression of valve lesions were demonstrated.

Group A Streptococcus encounters with host macrophages

Group A Streptococcus (GAS) is a leading human bacterial pathogen with diverse clinical manifestations. Macrophages constitute a critical first line of host defense against GAS infection, using numerous surface and intracellular receptors such as Toll-like receptors and inflammasomes for pathogen recognition and activation of inflammatory signaling pathways. Depending on the intensity of the GAS infection, activation of these signaling cascades may provide a beneficial early alarm for effective immune clearance, or conversely, may cause hyperinflammation and tissue injury during severe invasive infection. Although traditionally considered an extracellular pathogen, GAS can invade and replicate within macrophages using specific molecular mechanisms to resist phagolysosomal and xenophagic killing. Unraveling GAS-macrophage encounters may reveal new treatment options for this leading agent of infection-associated mortality. [Formula: see text].

Latent Rheumatic Heart Disease: Identifying the Children at Highest Risk of Unfavorable Outcome

BACKGROUND

Screening echocardiography has emerged as a potentially powerful tool for early diagnosis of rheumatic heart disease (RHD). The utility of screening echocardiography hinges on the rate of RHD progression and the ability of penicillin prophylaxis to improve outcome. We report the longitudinal outcomes of a cohort of children with latent RHD and identify risk factors for unfavorable outcomes.

METHODS

This was a prospective natural history study conducted under the Ugandan RHD registry. Children with latent RHD and ≥1 year of follow-up were included. All echocardiograms were re-reviewed by experts (2012 World Heart Federation criteria) for inclusion and evidence of change. Bi- and multivariable logistic regression, Kaplan-Meier analysis, and Cox proportional hazards models, as well, were developed to search for risk factors for unfavorable outcome and compare progression-free survival between those treated and not treated with penicillin. Propensity and other matching methods with sensitivity analysis were implemented for the evaluation of the penicillin effect.

RESULTS

Blinded review confirmed 227 cases of latent RHD: 164 borderline and 63 definite (42 mild, 21 moderate/severe). Median age at diagnosis was 12 years and median follow-up was 2.3 years (interquartile range, 2.0-2.9). Penicillin prophylaxis was prescribed in 49.3% with overall adherence of 84.7%. Of children with moderate-to-severe definite RHD, 47.6% had echocardiographic progression (including 2 deaths), and 9.5% had echocardiographic regression. Children with mild definite and borderline RHD showed 26% and 9.8% echocardiographic progression and 45.2% and 46.3% echocardiographic improvement, respectively. Of those with mild definite RHD or borderline RHD, more advanced disease category, younger age, and morphological mitral valve features were risk factors for an unfavorable outcome.

CONCLUSIONS

Latent RHD is a heterogeneous diagnosis with variable disease outcomes. Children with moderate to severe latent RHD have poor outcomes. Children with both borderline and mild definite RHD are at substantial risk of progression. Although long-term outcome remains unclear, the initial change in latent RHD may be evident during the first 1 to 2 years following diagnosis. Natural history data are inherently limited, and a randomized clinical trial is needed to definitively determine the impact of penicillin prophylaxis on the trajectory of latent RHD.

A multinational and multidisciplinary approach to treat CHD in paediatric age in Angola: initial experience of a medical-surgical centre for children with heart disease in Angola

BACKGROUND

Epidemiological patterns of cardiac disease differ between developed countries and African nations. Despite the collaborative efforts of developed countries, several obstacles hinder the implementation of successful programmes for the management of children with heart disease in Africa. Materials and methods This study is a retrospective analysis of a bi-national two-institution partnership programme for the treatment of children with congenital and acquired heart disease. In April, 2011, a continuous medical-surgical programme was inaugurated at Clínica Girassol in Luanda. The main goals were to initiate permanent and local delivery of services while training local teams, allowing autonomous medical and surgical management of children with heart disease.

RESULTS

Between April, 2011 and August, 2015, a total of 1766 procedures were performed on 1682 children. Of them, 1539 had CHD and 143 had acquired heart disease; 94 children underwent interventional treatment. A total of 1672 paediatric surgeries were performed on 1588 children: 1087 (65%) were performed with extracorporeal circulation and 585 (35%) were off-pump. The age distribution of the children was 4.5% (n=76) neonatal, 40.4% (n=675) between 30 days and 1 year, and 55.1% (n=921) over 1 year. There were 76 re-operations (4.5%) due to complications. The 30-day mortality rate was 4.2% (71 patients). Education-wise, several Angolan medical and surgical specialists were trained, allowing near-autonomous cardiac care delivery in children with heart disease.

CONCLUSION

An innovative cooperation model between a European and an African centre based on permanent delivery of care and education allowed for effective training of local teams and treatment of children with heart disease in their own environment.

Rheumatic Heart Disease in the Twenty-First Century

Rheumatic heart disease (RHD) is a chronic valvular disease resulting after severe or repetitive episodes of acute rheumatic fever (ARF), an autoimmune response to group A Streptococcus infection. RHD has been almost eliminated with improved social and health infrastructure in affluent countries while it remains a neglected disease with major cause of morbidity and mortality in many low- and middle-income countries, and resource-limited regions of high-income countries. Despite our evolving understanding of the pathogenesis of RHD, there have not been any significant advances to prevent or halt progression of disease in recent history. Long-term penicillin-based treatment and surgery remain the backbone of a RHD control program in the absence of an effective vaccine. The advent of echocardiographic screening algorithms has improved the accuracy of diagnosing RHD and has shed light on the enormous burden of disease. Encouragingly, this has led to a rekindled commitment from researchers in the most affected countries to advocate and take bold actions to end this disease of social inequality.

Effect of Early and Prophylactic Nonsteroidal Anti-Inflammatory Drugs on Flare Duration in Pediatric Acute-Onset Neuropsychiatric Syndrome: An Observational Study of Patients Followed by an Academic Community-Based Pediatric Acute-Onset Neuropsychiatric Syndrome Clinic

INTRODUCTION

Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) is characterized by the sudden onset of severe obsessive-compulsive symptoms and/or eating restriction along with at least two coinciding neuropsychiatric symptoms. When associated with group A Streptococcus, the syndrome is labeled Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infections (PANDAS). An abnormal immune response to infection and subsequent neuroinflammation is postulated to play an etiologic role. We evaluated the impact of nonsteroidal anti-inflammatory drug (NSAID) treatment on flare duration in PANS/PANDAS.

METHODS

Patient inclusion criteria: Patients were included if they had at least one neuropsychiatric deterioration ("flare") that met strict PANS/PANDAS research criteria and for which flare duration could be assessed. Flare inclusion criteria: Any flare that started before October 15, 2016 was included and followed until the flare resolved or until the end of our data collection (November 1, 2016). Flare exclusion criteria: Flares were excluded if they were incompletely resolved, treated with aggressive immunomodulation, or treated with NSAIDs late (>30 days of flare onset). Ninety-five patients met study inclusion criteria and collectively experienced 390 flares that met flare criteria. Data were analyzed using multilevel linear models, adjusting for demographics, disease, and treatment covariates.

RESULTS

NSAID use was associated with a significantly shorter flare duration. Flares not treated with NSAIDs had a mean duration of approximately 12.2 weeks (95% CI: 9.3-15.1). Flares that occurred while the child was on NSAID maintenance therapy were approximately 4 weeks shorter than flares not managed with NSAIDs (95% CI: 1.85-6.24; p < 0.0001). Flares treated with NSAIDs within 30 days of flare onset were approximately 2.6 weeks shorter than flares not managed with NSAIDs (95% CI: 0.43-4.68; p = 0.02). Flares treated prophylactically and those treated early with NSAIDs did not differ in duration (p = 0.26). Among the flares that received NSAID treatment within the first 30 days, earlier intervention was modestly associated with shorter flare durations (i.e., for each day that NSAID treatment was delayed, flare duration increased by 0.18 weeks; 95% CI: 0.03-0.33; p = 0.02), though it was not statistically significant after controlling for covariates (p = 0.06).

CONCLUSION

NSAIDs given prophylactically or within 30 days of flare onset may shorten neuropsychiatric symptom duration in patients with new-onset and relapsing/remitting PANS and PANDAS. A randomized placebo-control clinical trial of NSAIDs in PANS is warranted to formally assess treatment efficacy.

Course of Neuropsychiatric Symptoms After Introduction and Removal of Nonsteroidal Anti-Inflammatory Drugs: A Pediatric Observational Study

OBJECTIVE

Accumulating evidence suggests that anti-inflammatory interventions can modulate neuropsychiatric symptoms. Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) is characterized by an abrupt and dramatic onset of obsessive-compulsive (OC) symptoms and/or severely restrictive food intake and at least two coinciding, equally debilitating neuropsychiatric symptoms. When associated with group A Streptococcus, the syndrome is labeled Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infections (PANDAS). Here, we describe the course of neuropsychiatric symptoms in patients diagnosed with PANS and PANDAS after introduction or removal of nonsteroidal anti-inflammatory drugs (NSAIDs).

STUDY DESIGN

We reviewed the electronic medical records (EMR) of 218 consecutive patients evaluated in our Stanford PANS Clinic for patients who met strict PANS or PANDAS research criteria and received NSAIDs for arthritis, pain, and/or psychiatric symptoms. We describe neuropsychiatric symptoms that were noted in the EMR before, during, and after NSAIDs were introduced or removed as the sole change in pharmacologic treatment.

RESULTS

Seventy-seven patients were included in the current study. Of the 52 trials in which NSAID addition was the sole change in treatment, 16 (31%) coincided with an improvement in patients' neuropsychiatric symptoms. Of the 57 trials in which removal of NSAID treatment was the sole change in treatment, 20 (35%) coincided with escalation in patients' neuropsychiatric symptoms. Thirty patients (39%) experienced side effects, mainly mild gastrointestinal symptoms, which self-resolved after removal of NSAID, reduction of dose, or change in NSAID.

CONCLUSIONS

Improvement in neuropsychiatric symptoms was evident in roughly one-third of NSAID treatment trials. A randomized clinical trial will be necessary to confirm whether NSAIDs are successful in reducing neuropsychiatric symptoms in youth with PANS.

Pediatric Acute-Onset Neuropsychiatric Syndrome Response to Oral Corticosteroid Bursts: An Observational Study of Patients in an Academic Community-Based PANS Clinic

BACKGROUND

Sudden-onset severe obsessive-compulsive symptoms and/or severely restrictive food intake with at least two coinciding, similarly debilitating neuropsychiatric symptoms define Pediatric Acute-onset Neuropsychiatric Syndrome (PANS). When associated with Group A Streptococcus, the syndrome is labeled Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infections (PANDAS). An abnormal immune response to infection and subsequent neuroinflammation is postulated to play an etiologic role. Most patients have a relapsing-remitting course. Treatment outcome data for youth with PANS and PANDAS are limited.

METHODS

One hundred seventy-eight consecutive patients were seen in the Stanford PANS clinic between September 1, 2012 and January 15, 2016, of whom 98 met PANS or PANDAS criteria, had a single episode of PANS or relapsing/remitting course, and collectively experienced 403 flares. Eighty-five flares were treated with 102 total courses of oral corticosteroids of either short (4-5 days) or long (5 days-8 weeks) duration. Response to treatment was assessed within 14 days of initiating a short burst of corticosteroids and at the end of a long burst based on clinician documentation and patient questionnaires. Data were analyzed by using multilevel random-effects models.

RESULTS

Patients experienced shorter flares when treated with oral corticosteroids (6.4 ± 5.0 weeks vs. 11.4 ± 8.6 weeks) than when not treated (p < 0.001), even after controlling for presumed confounding variables, including age at flare, weeks since onset of PANS illness, sex, antibiotic treatment, prophylactic antibiotics, previous immunomodulatory treatment, maintenance anti-inflammatory therapy, psychiatric medications, and cognitive behavioral therapy (p < 0.01). When corticosteroids were given for the initial PANS episode, flares tended to be shorter (10.3 ± 5.7 weeks) than when not treated (16.5 ± 9.6 weeks) (p = 0.06). This difference was statistically significant after controlling for the relevant confounding variables listed earlier (p < 0.01). Earlier use of corticosteroids was associated with shorter flare durations (p < 0.001). Longer courses of corticosteroids were associated with a more enduring impact on the duration of neuropsychiatric symptom improvement (p = 0.014).

CONCLUSION

Corticosteroids may be a helpful treatment intervention in patients with new-onset and relapsing/remitting PANS and PANDAS, hastening symptom improvement or resolution. When corticosteroids are given earlier in a disease flare, symptoms improve more quickly and patients achieve clinical remission sooner. Longer courses of corticosteroids may result in more durable remissions. A double-blind placebo-controlled clinical trial of corticosteroids in PANS is warranted to formally assess treatment efficacy.

Variation, Indispensability, and Masking in the M protein

The M protein is the major surface-associated virulence factor of group A Streptococcus (GAS) and an antigenically variable target of host immunity. How selection pressures to escape immune recognition, maintain indispensable functions, and mask vulnerabilities have shaped the sequences of the >220M protein types is unclear. Recent experiments have shed light on this question by showing that, hidden within the antigenic variability of many M protein types, are sequence patterns conserved for recruiting human C4b-binding protein (C4BP). Other host factors may be recruited in a similar manner by conserved but hidden sequence patterns in the M protein. The identification of such patterns may be applicable to the development of a GAS vaccine.

A Critical Role of Zinc Importer AdcABC in Group A Streptococcus-Host Interactions During Infection and Its Implications for Vaccine Development

Bacterial pathogens must overcome host immune mechanisms to acquire micronutrients for successful replication and infection. Streptococcus pyogenes, also known as group A streptococcus (GAS), is a human pathogen that causes a variety of clinical manifestations, and disease prevention is hampered by lack of a human GAS vaccine. Herein, we report that the mammalian host recruits calprotectin (CP) to GAS infection sites and retards bacterial growth by zinc limitation. However, a GAS-encoded zinc importer and a nuanced zinc sensor aid bacterial defense against CP-mediated growth inhibition and contribute to GAS virulence. Immunization of mice with the extracellular component of the zinc importer confers protection against systemic GAS challenge. Together, we identified a key early stage host-GAS interaction and translated that knowledge into a novel vaccine strategy against GAS infection. Furthermore, we provided evidence that a similar struggle for zinc may occur during other streptococcal infections, which raises the possibility of a broad-spectrum prophylactic strategy against multiple streptococcal pathogens.

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Host employs calprotectin to impose zinc (Zn) limitation on the human pathogen group A streptococcus (GAS) during infection.

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As a defense, GAS uses a sensor, AdcR, to monitor Zn availability, and a high-affinity transporter, AdcABC, to acquire Zn.

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Finally, we characterized the extracellular subunit of AdcA as a vaccine candidate to protect mice from GAS infections.

There is an urgent need for a human vaccine to protect against diseases caused by human pathogen, group A streptococcus (GAS). Herein, we identified the key molecular players involved in the battle between the host and invading bacteria for the critical nutrient zinc. The host recruits calprotectin at GAS infection sites to limit zinc availability to the pathogen. The pathogen senses the alterations in zinc availability using a sensor, AdcR, and outcompetes calprotectin by employing a high-affinity zinc uptake system, AdcABC. Using this knowledge, we developed a successful vaccination strategy by immunization with AdcA and demonstrated protection against GAS infections.

Immuno-nephelometric determination of group streptococcal anti-streptolysin O titres (ASOT) from dried blood spots: Method for validating a new assay

This study was designed to determine the sensitivity and reproducibility of recovering anti-streptolysin O titres (ASOT) from dried blood spot (DBS) samples, a methodologic subcomponent of the penicillin pharmacokinetic studies in children receiving secondary prophylaxis with intramuscular benzathine penicillin for acute rheumatic fever.