Risk factors for group A streptococcal pharyngitis and skin infections: A case control study

Magnitude and associated factors of atrial fibrillation, and its complications among adult rheumatic heart diseases patients in governmental hospitals in Bahir Dar Town, Northwest Ethiopia 2024

INTRODUCTION

Atrial fibrillation (AF) is characterized by high frequency stimulation of the atrium, causes dyssynchronous atrial contraction and irregular ventricular excitation. It is the most known cardiac arrhythmia in adults, doubles the risk of stroke five times and is associated with an increasing public health burden. This study was aimed to assess the magnitude and associated factors of atrial fibrillation and its complication among adult rheumatic heart diseases patients in governmental hospitals in Bahir Dar town, Northwest Ethiopia 2024.

METHODS

An institutional based cross-sectional study design was conducted with a sample size of 421. A simple random sampling technique was used to select participants. The data were entered into the Statistical Package for the Social Sciences (SPSS) version 26 for analysis. Adjusted Odds Ratio (AOR) with a 95% confidence interval was used to determine associated factors of atrial fibrillation. A binary logistic regression model was used, and a P-value < 0.05 in multivariate was considered as a statistically significant.

RESULTS

The response rate was 95% and atrial fibrillation was developed in 51.2% of patient. Majority of them were Female (56%). The median age of patients was 41, with an interquartile range (IQR) of 26-51. Age > 50 years old (AOR = 7.20(2.03-25.46)), sever tricuspid regurgitation 4.50(1.18-17.20)), and left ventricular ejection fraction (LVEF) % (AOR = 0.94(0.89-0.99)), left atrium size (AOR = 1.23(1.14-1.33)) were independently associated with atrial fibrillation. For every unit increment of left ventricular ejection fraction in percent, the odds of developing atrial fibrillation decreased by 6%. For every unit increment of left atrial size in millimeter2 (mm2), the odds of developing atrial fibrillation increased by 23%. The present study showed that complication related to AF was heart failure (HF) (72.8%), ischemic stroke (34.4%), systemic thromboembolism (12.1).

CONCLUSION

More than half of the study participants were found to have atrial fibrillation in patients with rheumatic heart disease. Being age > 50 years old, left atrium size, severity of tricuspid regurgitation (severe), and LVEF% were associated in developing atrial fibrillation. The atrial fibrillation was linked to an increased risk of ischemic stroke, heart failure, systemic thromboembolism, and death.

Streptococcus pyogenes pharyngitis elicits diverse antibody responses to key vaccine antigens influenced by the imprint of past infections

Knowledge gaps regarding human immunity to Streptococcus pyogenes have impeded vaccine development. To address these gaps and evaluate vaccine candidates, we established a human challenge model of S. pyogenes pharyngitis. Here, we analyse antibody responses in serum and saliva against 19 antigens to identify characteristics distinguishing 19 participants who developed pharyngitis and 6 who did not. We show that pharyngitis elicits serum IgG responses to key vaccine antigens and a muted mucosal IgA response, whereas IgG responses are minimal and IgA responses more pronounced in participants without pharyngitis. Serum IgG responses to pharyngitis in adult participants resemble those in children and are inversely correlated with the magnitude of pre-existing responses. While a straightforward correlate of protection is not evident, baseline antibody signatures distinguish clinical and immunological outcomes following experimental challenge. This highlights the influence of a complex humoral imprint from previous exposure, relevant for interpreting immunogenicity in forthcoming vaccine trials.

The intricate pathogenicity of Group A Streptococcus: A comprehensive update

Group A Streptococcus (GAS) is a versatile pathogen that targets human lymphoid, decidual, skin, and soft tissues. Recent advancements have shed light on its airborne transmission, lymphatic spread, and interactions with neuronal systems. GAS promotes severe inflammation through mechanisms involving inflammasomes, IL-1β, and T-cell hyperactivation. Additionally, it secretes factors that directly induce skin necrosis via Gasdermin activation and sustains survival and replication in human blood through sophisticated immune evasion strategies. These include lysis of erythrocytes, using red cell membranes for camouflage, resisting antimicrobial peptides, evading phagocytosis, escaping from neutrophil extracellular traps (NETs), inactivating chemokines, and cleaving targeted antibodies. GAS also employs molecular mimicry to traverse connective tissues undetected and exploits the host's fibrinolytic system, which contributes to its stealth and potential for causing autoimmune conditions after repeated infections. Secreted toxins disrupt host cell membranes, enhancing intracellular survival and directly activating nociceptor neurons to induce pain. Remarkably, GAS possesses mechanisms for precise genome editing to defend against phages, and its fibrinolytic capabilities have found applications in medicine. Immune responses to GAS are paradoxical: robust responses to its virulence factors correlate with more severe disease, whereas recurrent infections often show diminished immune reactions. This review focuses on the multifaceted virulence of GAS and introduces novel concepts in understanding its pathogenicity.

Systematic Review of Household Transmission of Strep A: A Potential Site for Prevention That Has Eluded Attention

BACKGROUND

Although Streptococcus pyogenes (Strep A) is the sixth-most common infectious disease globally, its transmission within the household remains an understudied driver of infection. We undertook a systematic review to better understand the transmission of Strep A among people within the home, while highlighting opportunities for prevention.

METHODS

A search strategy was applied to 5 databases between September 2022 and March 2023. Results were limited to articles published between January 2000 and March 2023. Texts were reviewed by 2 authors and the following data extracted: article details (title, author, year), study type, transmission year, country, participant age, infection status, molecular testing, and transmission mode. Funding was provided by the Australian National Health and Medical Research Council (GNT2010716).

RESULTS

The final analysis comprised 28 texts. Only 7 studies (25.0%) provided sufficient detail to identify the Strep A transmission mode: contact (n = 4), vehicle (bedding, clothing, other fabric, and medical equipment; n = 2), and contact with animals (n = 1). All others were classified as household (specific mode unascertainable). Most articles reported outbreaks involving invasive Strep A infections.

CONCLUSIONS

There is limited literature regarding household transmission of Strep A. Understanding transmission in this setting remains imperative to guide control methods.

An acute rheumatic fever immune signature comprising inflammatory markers, IgG3, and Streptococcus pyogenes-specific antibodies

Understanding the immune profile of acute rheumatic fever (ARF), a serious post-infectious sequelae of Streptococcal pyogenes (group A Streptococcus [GAS]), could inform disease pathogenesis and management. Circulating cytokines, immunoglobulins, and complement were analyzed in participants with first-episode ARF, swab-positive GAS pharyngitis and matched healthy controls. A striking elevation of total IgG3 was observed in ARF (90% > clinical reference range for normal). ARF was also associated with an inflammatory triad with significant correlations between interleukin-6, C-reactive protein, and complement C4 absent in controls. Quantification of GAS-specific antibody responses revealed that subclass polarization was remarkably consistent across the disease spectrum; conserved protein antigens polarized to IgG1, while M-protein responses polarized to IgG3 in all groups. However, the magnitude of responses was significantly higher in ARF. Taken together, these findings emphasize the association of exaggerated GAS antibody responses, IgG3, and inflammatory cytokines in ARF and suggest IgG3 testing could beneficially augment clinical diagnosis.

The Emergence and Impact of the M1UK Lineage on Invasive Group A Streptococcus Disease in Aotearoa New Zealand

M1UK is associated with current surges in invasive infection globally, partly due to increased production of superantigen streptococcal pyrogenic exotoxin A. We show that M1UK is now the dominant invasive emm1 lineage in Aotearoa New Zealand and is genomically related to community infections, suggesting that measures that effectively prevent group A Streptococcus pharyngitis in children could reduce invasive disease.

A survey of antibiotic resistance patterns among Group A Streptococcus isolated from invasive and non-invasive infections in Cape Town, South Africa

Background

There is concern regarding the increasing resistance of Group A streptococcus (GAS) to routinely used antibiotics. GAS is a common cause of bacterial pharyngitis and more severe invasive infections such as septicaemia. Furthermore, GAS pharyngitis is the antecedent for serious conditions such as rheumatic fever and rheumatic heart disease. The study aimed to determine the antimicrobial susceptibility patterns of GAS cultured from patients with invasive and non-invasive infections from Cape Town, as part of the AFROStrep Registry.

Methods

Samples were provided by the AFROStrep Registry, a continental endeavour aiming to document Streptococcus pyogenes infection in Africa and create the first biorepository of its kind. Ninety-five GAS isolates (invasive, n = 40; non-invasive, n = 55) were evaluated for resistance to a panel of 20 antibiotics using the Sensititre® STP6F system with MICs interpreted by CLSI break points.

Results

Amongst all isolates, highest levels of resistance were observed with respect to tetracycline (8.33 %), followed by azithromycin (1.04 %) and erythromycin (1.04 %). No resistance to the remaining antibiotics was detected amongst all isolates. No differences with regard to MIC values were observed between isolates from invasive and non-invasive infections (p-value >0.05 for all antibiotics).

Conclusion

GAS remains susceptible to routine-antimicrobial agents used in our low-resourced setting. Eight percent of the GAS isolates were resistant to tetracycline, and we did not observe macrolide resistance as reported in high income countries. This is the first study to report on the antimicrobial patterns of GAS in South Africa. These results address a critical gap in the available data on GAS in Africa and specifically South Africa and, thus, aid in avoiding therapeutic failures.

The roles of immuno-modulator treatment and echocardiographic screening in rheumatic fever and rheumatic heart disease control: research from Aotearoa, New Zealand

This review summarises advances in research from Aotearoa, New Zealand (NZ) that have potential to reduce the inequitable distribution of acute rheumatic fever (ARF) and rheumatic heart disease (RHD). ARF incidence and RHD prevalence are unacceptably inequitable for Māori and Pacifica. Recent qualitative research has demonstrated mismatches between the lived experience of those with ARF/RHD and health service experience they encounter. NZ-led research has contributed knowledge to all stages of disease prevention (primordial, primary and secondary) and for tertiary management. Modifiable risk factors for ARF are racism across health sectors, household crowding, barriers to accessing primary health care, a high intake of sugar-sweetened beverages and preceding sore throat and skin infections. NZ research has evaluated the impact of a large-scale sore throat management programme and Streptococcal A vaccine development. This review highlights two programme domains of research by the authors that have the potential to reduce the burden of chronic RHD: firstly, effective immunomodulation of ARF to reduce the severity of carditis, with current clinical trials of hydroxychloroquine in NZ; secondly, the development of echocardiographic screening of previously undetected RHD. This now meets criteria for an effective screening test and has potential translation for disease control of RHD.

A worldwide population of Streptococcus pyogenes strains circulating among school-aged children in Auckland, New Zealand: a genomic epidemiology analysis

Background

Acute rheumatic fever (ARF) is a serious post-infectious sequala of Group A Streptococcus (GAS, Streptococcus pyogenes). In New Zealand (NZ) ARF is a major cause of health inequity. This study describes the genomic analysis of GAS isolates associated with childhood skin and throat infections in Auckland NZ.

Methods

Isolates (n = 469) collected between March 2018 and October 2019 from the throats and skin of children (5-14 years) underwent whole genomic sequencing. Equal representation across three ethnic groups was ensured through sample quotas with isolates obtained from Indigenous Māori (n = 157, 33%), NZ European/Other (n = 149, 32%) and Pacific Peoples children (n = 163, 35%). Using in silico techniques isolates were classified, assessed for diversity, and examined for distribution differences between groups. Comparisons were also made with GAS strains identified globally.

Findings

Genomic analysis revealed a diverse population consisting of 65 distinct sequence clusters. These sequence clusters spanned 49 emm-types, with 11 emm-types comprised of several, distinct sequence clusters. There is evidence of multiple global introductions of different lineages into the population, as well as local clonal expansion. The M1UK lineage comprised 35% of all emm1 isolates.

Interpretation

The GAS population was characterized by a high diversity of strains, resembling patterns observed in low- and middle-income countries. However, strains associated with outbreaks and antimicrobial resistance commonly found in high-income countries were also observed. This unique combination poses challenges for vaccine development, disease management and control.

Funding

The work was supported by the Health Research Council of New Zealand (HRC), award number 16/005.

Group A β-hemolytic Streptococcal Pharyngitis: An Updated Review

BACKGROUND

Group A ß-hemolytic Streptococcus (GABHS) is the leading bacterial cause of acute pharyngitis in children and adolescents worldwide.

OBJECTIVE

This article aims to familiarize clinicians with the clinical manifestations, evaluation, diagnosis, and management of GABHS pharyngitis.

METHODS

A search was conducted in December 2022 in PubMed Clinical Queries using the key term "group A β-hemolytic streptococcal pharyngitis". This review covers mainly literature published in the previous ten years.

RESULTS

Children with GABHS pharyngitis typically present with an abrupt onset of fever, intense pain in the throat, pain on swallowing, an inflamed pharynx, enlarged and erythematous tonsils, a red and swollen uvula, enlarged tender anterior cervical lymph nodes. As clinical manifestations may not be specific, even experienced clinicians may have difficulties diagnosing GABHS pharyngitis solely based on epidemiologic or clinical grounds alone. Patients suspected of having GABHS pharyngitis should be confirmed by microbiologic testing (e.g., culture, rapid antigen detection test, molecular point-of-care test) of a throat swab specimen prior to the initiation of antimicrobial therapy. Microbiologic testing is generally unnecessary in patients with pharyngitis whose clinical and epidemiologic findings do not suggest GABHS. Clinical score systems such as the Centor score and McIssac score have been developed to help clinicians decide which patients should undergo diagnostic testing and reduce the unnecessary use of antimicrobials. Antimicrobial therapy should be initiated without delay once the diagnosis is confirmed. Oral penicillin V and amoxicillin remain the drugs of choice. For patients who have a non-anaphylactic allergy to penicillin, oral cephalosporin is an acceptable alternative. For patients with a history of immediate, anaphylactic-type hypersensitivity to penicillin, oral clindamycin, clarithromycin, and azithromycin are acceptable alternatives.

CONCLUSION

Early diagnosis and antimicrobial treatment are recommended to prevent suppurative complications (e.g., cervical lymphadenitis, peritonsillar abscess) and non-suppurative complications (particularly rheumatic fever) as well as to reduce the severity of symptoms, to shorten the duration of the illness and to reduce disease transmission.

Research priorities for the primordial prevention of acute rheumatic fever and rheumatic heart disease by modifying the social determinants of health

The social determinants of health (SDH), such as access to income, education, housing and healthcare, strongly shape the occurrence of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) at the household, community and national levels. The SDH are systemic factors that privilege some more than others and result in poverty and inequitable access to resources to support health and well-being. Primordial prevention is the modification of SDH to improve health and reduce the risk of disease acquisition and the subsequent progression to RHD. Modifying these determinants using primordial prevention strategies can reduce the risk of exposure to Group A Streptococcus, a causative agent of throat and skin infections, thereby lowering the risk of initiating ARF and its subsequent progression to RHD.This report summarises the findings of the Primordial Prevention Working Group-SDH, which was convened in November 2021 by the National Heart, Lung, and Blood Institute to assess how SDH influence the risk of developing RHD. Working group members identified a series of knowledge gaps and proposed research priorities, while recognising that community engagement and partnerships with those with lived experience will be integral to the success of these activities. Specifically, members emphasised the need for: (1) global analysis of disease incidence, prevalence and SDH characteristics concurrently to inform policy and interventions, (2) global assessment of legacy primordial prevention programmes to help inform the co-design of interventions alongside affected communities, (3) research to develop, implement and evaluate scalable primordial prevention interventions in diverse settings and (4) research to improve access to and equity of services across the RHD continuum. Addressing SDH, through the implementation of primordial prevention strategies, could have broader implications, not only improving RHD-related health outcomes but also impacting other neglected diseases in low-resource settings.

The rise and fall of acute rheumatic fever and rheumatic heart disease: a mini review

Introduction

The incidences of acute rheumatic fever (ARF) and rheumatic heart disease (RHD), which were leading causes of death in children in the 1920s, have decreased substantially. Considering the recent resurgence of scarlet fever and increased incidence of streptococcal pharyngitis in children, an investigation of the current status of ARF and RHD may be worthwhile.

Objective

To summarize the prevalence trends, pathogenic factors, and prevention strategies for ARF and RHD in children.

Methods

A selective search of literature published between January 1920 and February 2023 was done in PubMed, using the terms "acute rheumatic fever", "rheumatic heart disease", "group A Streptococcus", "pharyngitis", "pharyngeal tonsillitis", "scarlet fever", "impetigo", "obstructive sleep apnea syndrome" and "child".

Results

Overcrowded homes and inadequate sanitation led to recurrent group A streptococcal infection, and the causal relationship between group A streptococcal infection and ARF/RHD was well established. Streptococcal infectious diseases, such as group A streptococcal pharyngeal tonsillitis, SF, impetigo, and obstructive sleep apnea syndrome, were associated with the occurrence of ARF and RHD. ARF and RHD were still prevalent in young people of developing countries and economically poor populations of high-income countries. Universal disease registration systems were critical to locating disease outbreaks, tracking disease transmission, and identifying high-risk populations. Four-level prevention strategies were effective in reducing the incidence and mortality of ARF and RHD.

Conclusions

Registry and preventive measures for ARF and RHD should be strengthened in areas of dense population; poor sanitation; resurgence of SF; and high incidence of streptococcal pharyngitis, impetigo, and obstructive sleep apnea syndrome.

Risk factors for acute rheumatic fever: A case-control study

BACKGROUND

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) remain an inequitable cause of avoidable suffering and early death in many countries, including among Indigenous Māori and Pacific populations in New Zealand. There is a lack of robust evidence on interventions to prevent ARF. This study aimed to identify modifiable risk factors, with the goal of producing evidence to support policies and programs to decrease rates of ARF.

METHODS

A case-control study was undertaken in New Zealand using hospitalised, first episode ARF cases meeting a standard case-definition. Population controls (ratio of 3:1) were matched by age, ethnicity, socioeconomic deprivation, location, sex, and recruitment month. A comprehensive, pre-tested questionnaire was administered face-to-face by trained interviewers.

FINDINGS

The study included 124 cases and 372 controls. Multivariable analysis identified strong associations between ARF and household crowding (OR 3·88; 95%CI 1·68-8·98) and barriers to accessing primary health care (OR 2·07; 95% CI 1·08-4·00), as well as a high intake of sugar-sweetened beverages (OR 2·00; 1·13-3·54). There was a marked five-fold higher ARF risk for those with a family history of ARF (OR 4·97; 95% CI 2·53-9·77). ARF risk was elevated following self-reported skin infection (aOR 2·53; 1·44-4·42) and sore throat (aOR 2·33; 1·49-3·62).

INTERPRETATION

These globally relevant findings direct attention to the critical importance of household crowding and access to primary health care as strong modifiable causal factors in the development of ARF. They also support a greater focus on the role of managing skin infections in ARF prevention.

FUNDING

This research was funded by the Health Research Council of New Zealand (HRC) Rheumatic Fever Research Partnership (supported by the New Zealand Ministry of Health, Te Puni Kōkiri, Cure Kids, Heart Foundation, and HRC) award number 13/959.