Browsing by Subject "Group A Streptococcus"

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    Genomic insights into Group A Streptococcus pathogenesis
    (2025) Rampersadh, Kimona; Engel, Mark; Moodley, Clinton
    Group A Streptococcus (GAS) is a bacterium responsible for invasive and non-invasive infections in humans. The sequela of an untreated or undertreated GAS pharyngitis include Rheumatic Fever (RF) and Rheumatic Heart Disease (RHD). Despite evidence for the effectiveness of antibiotics such as penicillin, the burden of GAS remains high in low- and middle-income countries (LMICs) compared to high-income countries (HIC), thus necessitating the development of innovative prevention tools and improve treatment strategies tailored to LMICs. However, the pathogenetic role of GAS is poorly understood. There remains limited studies conducted across Africa, compared with HICs, documenting virulence profiles associated with GAS infection, despite the fact that an increased burden of GAS is seen in LMICs. Only a few whole genome sequencing (WGS) studies in GAS have been conducted in Africa, but none have been performed in Southern Africa. To address this knowledge gap, first, I conducted evidence-based reviews on virulence factors in invasive GAS disease (study 1) and antimicrobial resistance (AMR) of GAS in LMICs (study 2). Thereafter, on a collection of invasive and non-invasive GAS isolates from Cape Town, South Africa, performed antimicrobial susceptibility testing (study 3) and employed WGS to identify the frequency of virulence factors and AMR determinants (study 4). In brief, I provide comprehensive evidence-based data linking hasA, speA, speK, and speG to invasive GAS infections, while factors like smeZ, ssa, and sic show inverse associations; document penicillin's continued high efficacy, alongside notable resistance to macrolides and tetracycline observed in LMICs; I demonstrate low levels of antimicrobial resistance in GAS in Cape Town, with most antibiotics being effective and only minimal resistance to macrolides and tetracycline; I report that GAS isolates from Cape Town exhibit a diverse range of virulence factors and AMR genes, with notable geographic variations. My research contributes to the growing evidence base to inform future efforts at global control of GAS infections. In addition to confirming antibiotic sensitivities peculiar to our setting, suggest that GAS profile variations should be taken into account to gain a deeper understanding of GAS infection in a local context.
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    Modes of transmission and attack rates of group A Streptococcal infection: a protocol for a systematic review and meta-analysis
    (2021-03-31) Barth, Dylan D; Daw, Jessica; Xu, Ruomei; Enkel, Stephanie; Pickering, Janessa; McRae, Tracy; Engel, Mark E; Carapetis, Jonathan; Wyber, Rosemary; Bowen, Asha C
    Background Group A Streptococcus (Strep A) is an important cause of mortality and morbidity globally. This bacterium is responsible for a range of different infections and post-infectious sequelae. Summarising the current knowledge of Strep A transmission to humans will address gaps in the evidence and inform prevention and control strategies. The objective of this study is to evaluate the modes of transmission and attack rates of group A streptococcal infection in human populations. Methods This systematic review protocol was prepared according to the Preferred Reporting Items for Systematic reviews and Meta-analysis Protocols (PRISMA-P) 2015 Statement. Using a comprehensive search strategy to identify any transmission studies that have been published in English since 1980, full-text articles will be identified and considered for inclusion against predefined criteria. We will include all studies reporting on Strep A transmission, who have identified a mode of transmission, and who reported attack rates. Risk of bias will be appraised using an appropriate tool. Our results will be described narratively and where feasible and appropriate, a meta-analysis utilizing the random-effects model will be used to aggregate the incidence proportions (attack rates) for each mode of transmission. In addition, we will also evaluate the emm genotype variants of the M protein causing Strep A infection and the association with transmission routes and attack rates, if any, by setting, socioeconomic background and geographical regions. Discussion We anticipate that this review will contribute to elucidating Strep A modes of transmission which in turn, will serve to inform evidence-based strategies including environmental health activities to reduce the transmission of Strep A in populations at risk of severe disease. Trial registration Systematic review registration: PROSPERO ( CRD42019138472 ).
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    The prevalence of Group A Beta-Hemolytic Streptococci carriage in children in Africa: a systematic review
    (2015) Moloi, Annesinah; Engel, Mark E; Abdullahi, Leila H
    Asymptomatic children can be a major reservoir of pharyngeal Group A Streptococcus (GAS) with reported figures ranging from <10% to >20% in developing countries. There is a need to document GAS carriage in school children, which, together with the molecular characterisation (M-typing) of strains harboured in the pharynx of carriers, will help to ascertain the extent to which disease strains are prevalent amongst carriers. This background information would serve to assist healthcare providers in diagnosing symptomatic GAS pharyngitis, as well as could potentially contribute to the development of a GAS vaccine. Currently, data on GAS carriage prevalence and M-type distribution in African countries are largely scant. We therefore undertook to perform a systematic review to determine the prevalence and type distribution of asymptomatic streptococcus carriage in children aged 5 -15years, residing in African countries. Methods: We conducted a comprehensive literature search among a number of databases, using an African search filter to identify GAS prevalence studies that report on children between the ages of 5 - 15 years who reside in African countries. Electronic searches were complemented by a hand search performed on reference lists of potentially included studies. The search was not limited by year of publication and language. Two evaluators independently reviewed, rated, and abstracted data from each article. Prevalence estimates were pooled in a meta-analysis and stratified according to region and study design using Stata®. Specifically, we applied the random effects metaprop routine to aggregate prevalence estimates and account for between study variability in calculating the overall pooled estimates and 95% CI for GAS carriage prevalence.