Prevalence of group A Streptococcal infection in Africa to inform GAS vaccines for rheumatic heart disease: A systematic review and meta-analysis

Streptococcus pyogenes carriage rate, associated factors and antimicrobial susceptibility profiles among urban and rural schoolchildren at Gondar city, Northwest Ethiopia

Streptococcus pyogenes remains one of the top ten causes of mortality from infectious diseases. Children in low-income nations have high carrier rates of Streptococcus pyogenes, which can serve as a source of infections, including simple superficial infections that may lead to invasive and post-streptococcal diseases, particularly among schoolchildren. This study aimed to assess the prevalence of Streptococcus pyogenes, associated factors, and antimicrobial susceptibility profiles among urban and rural public schoolchildren in Gondar City, Northwest Ethiopia. A school-based comparative cross-sectional study was conducted via a multistage sampling technique among elementary schoolchildren from April to June 2022 in Gondar City. Sociodemographic and clinical data were collected via a pretested structured questionnaire. Standard microbiological methods were used to collect and process throat swabs to isolate Streptococcus pyogenes. An antimicrobial susceptibility test was performed via the disk diffusion method. Epi-Info version 7.2.5 was used to enter the data, which were then exported to SPSS version 25 for analysis. Logistic regression analysis was used to determine the strength of associations between variables, and p < 0.05 was considered statistically significant. The overall prevalence of Streptococcus pyogenes in 438 children was 11.2% (n = 49), with 71.43% (35/49) being urban and 28.57% (14/49) being rural. Low-income parents, hospital admission history, and cigarette smoking in the home were found to be substantially linked with Streptococcus pyogenes carriage among students (p < 0.05). All the Streptococcus pyogenes isolates were susceptible (100%) to penicillin and cefotaxime, but 18.8% and 12.25% of the isolates were resistant to amoxicillin and tetracycline, respectively. The prevalence of Streptococcus pyogenes throat carriage among was intermediate. All the isolates were sensitive to penicillin and cefotaxime, but 18.8% and 12.25% of the isolates were resistant to amoxicillin and tetracycline, respectively. Thus, regular screening and surveillance of Streptococcus pyogenes among schoolchildren should be conducted to minimize carriage or infections and maintain the rational use of antimicrobials. Health education about cigarette smoking in the house also needs to be provided to and the community.

Chains of misery: surging invasive group A streptococcal disease

PURPOSE OF REVIEW

We describe the epidemiology of the recent global surge in invasive group A streptococcal (GAS) disease and consider its proximate and distal causes. We highlight important knowledge gaps regarding clinical management and discuss potential strategies for prevention.

RECENT FINDINGS

Rates of invasive GAS (iGAS) disease were increasing globally prior to the COVID-19 pandemic. Since mid-2022, following the worst years of the pandemic in 2020 and 2021, many countries with systems to monitor GAS syndromes have reported surges in cases of iGAS concurrent with increased scarlet fever, pharyngitis, and viral co-infections. The emergence of the hypervirulent M1 UK strain as a cause of iGAS, particularly in high income countries, is concerning. New data are emerging on the transmission dynamics of GAS. GAS remains universally susceptible to penicillin but there are increasing reports of macrolide and lincosamide resistance, particularly in invasive isolates, with uncertain clinical consequences. Intravenous immunoglobulin is used widely for streptococcal toxic shock syndrome and necrotizing soft tissue infections, although there is limited clinical evidence, and none from a completed randomized controlled trial. Intensive and expensive efforts at population-level control of GAS infections and postinfectious autoimmune complications have been only partially successful. The great hope for control of GAS diseases remains vaccine development. However, all modern vaccine candidates remain in the early development stage.

SUMMARY

In many countries, iGAS rates surged from mid-2022 in the aftermath of pandemic control measures and physical distancing. The emergence of a dominant hypervirulent strain is an important but incomplete explanation for this phenomenon. Clinical management of iGAS remains highly empirical and new data has not emerged. A vaccine remains the most likely means of achieving a sustainable reduction in the burden of iGAS.

Rheumatic Heart Disease Burden in Africa and the Need to Build Robust Infrastructure

Rheumatic heart disease (RHD) is an important public health problem in Africa. Mapping the epidemiology of RHD involves elucidating its geographic distribution, temporal trends, and demographic characteristics. The prevalence of RHD in Africa varies widely, with estimates ranging from 2.9 to 30.4 per 1,000 population. Factors contributing to this burden include limited access to health care, poverty, lack of research interest, and genetic fragility. Studies have highlighted differences in group A Streptococcus (GAS) incidence among different African countries, emphasizing the importance of effective monitoring and intervention strategies. RHD epidemiological mapping in Africa indicates regional differences and socioeconomic determinants. The high prevalence among females in most studies and among children underscores the urgency for targeted interventions. Diagnosing RHD in Africa faces challenges of inaccessibility of health facilities and trained personnel. Efforts to develop cost-effective and accessible diagnostic tools, such as mobile/portable echocardiography machines, molecular biomarkers such as Tenascin-C and microRNA expression profile shows promise for accurate diagnosis of RHD, but their validation and utilization is limited due to resource constraints. Furthermore, lack of an effective licensed vaccine for GAS causes significant retardation in RHD control in Africa. Addressing the burden of RHD in Africa and other low- and middle-income countries requires robust RHD biomarkers and effective vaccines. This review provides a comprehensive overview of the landscape of RHD in Africa, covering the bacteriology of GAS, the burden of GAS infections, exploring diagnostic avenues, challenges, and opportunities in RHD biomarkers, diagnosis, effective prevention strategies, and RHD management in Africa.

Prevalence, Antibiotic Susceptibility Pattern and Associated Factors of Streptococcus pyogenes among Pediatric Patients with Acute Pharyngitis in Sidama, Southern Ethiopia

Background

Streptococcus pyogenes is the most frequent cause of pharyngitis and skin infections in children and causes immune complications like rheumatic fever and rheumatoid heart disease (RHD), particularly in developing countries like Ethiopia. The aim of this study was to determine the prevalence, antibiotic resistance pattern, and associated factors of Streptococcus pyogenes among pediatric patients suspected of acute pharyngitis in Sidama Region, Southern Ethiopia.

Methods

A cross-sectional study was conducted on 213 acute pharyngitis suspected pediatric patients from April to September 2022 at Hawassa University Compressive Specialized Hospital and Yirgalem Hospital. Sociodemographic and clinical data were collected using a structured questionnaire. A throat swab was cultured to isolate S. pyogenes, and antimicrobial susceptibility testing was done using standard bacteriological techniques. Data were analyzed using SPSS version 25, and P value of <0.05 was considered as statistically significant.

Result

Out of 213 throat swabs cultured, 22 (10.3%) with 95% CI (6.6-14.6%) were S. pyogenes positive. All isolates of S. pyogenes were sensitive to penicillin and amoxicillin. In contrast, 8 (36.4%) isolates exhibited resistance to tetracycline, 7 (31.8%) to ceftriaxone, 6 (27.3%) to erythromycin, and 5 (22.7%) isolates showed multidrug resistance. The presence of palatal petechiae (P=0.037) and tonsillar swelling or exudate (P=0.007) were significantly associated with S. pyogenes carriage in children suspected of having acute pharyngitis.

Conclusion

In this study, the prevalence of S. pyogenes among children suspected with acute pharyngitis was low compared to other studies. The isolates showed a high level of resistance to commonly used antibiotics. Therefore, the treatment of pediatric acute S. pyogenes pharyngitis should depend on an antimicrobial susceptibility test. Furthermore, evaluation of S. pyogenes pediatric acute pharyngitis risk factors and tracking of antibiotic resistance are crucial in the controlling of pediatric acute S. pyogenes pharyngitis.

Health-seeking behaviour and beliefs around sore throat in The Gambia: A qualitative study

Group A Streptococcus (Strep A) bacteria causes a broad spectrum of diseases. The most common manifestations of Strep A infection are sore throat and pus-producing skin infections such as impetigo. Complications of Strep A infection can lead to inflammation in the bones, muscles, joints, and internal organs causing acute rheumatic fever and rheumatic heart disease (RHD). In The Gambia, the RHD burden is thought to be very high. However, epidemiological data is minimal, and Strep A control programmes do not exist. This study aimed to explore common beliefs and practices related to sore throats among primary caregivers of children, and healthcare providers in a community with a high Strep A disease burden. Four informal conversations with providers and fifteen semi-structured interviews with caregivers were conducted in the peri-urban area of Sukuta, The Gambia. Sampling was purposive and gradual, beginning from households identified to have recently experienced sore throat through a parallel cohort study. Themes explored in qualitative analysis included: sore throat causal attributions and diagnoses, care practises, health-seeking behaviour, and perceived barriers to using the biomedical sector. We found that sore throats were typically perceived to affect one child in a family, disproportionately or exclusively. Sore throats were rarely perceived as life-threatening, and awareness of links between sore throat and ARF or RHD was not reported among caregivers or providers in this study population. Most cases of sore throat were initially managed at home using traditional medicine which delayed resort to antibiotics, though in two instances of severe pain with the presence of exudate, fear that the child's life was at risk prompted care-seeking through the formal health system. Our findings can inform the development of tailored strategies to increase community knowledge of the potential long-term consequences of sore throats and appropriate care-seeking, alongside improvements in the health system, to prevent Strep A sequelae effectively.

Throat carriage rate, associated factors, and antimicrobial susceptibility pattern of group A Streptococcus among healthy school children in Jigjiga City, Eastern Ethiopia

Background

Group A Streptococcus has been recognized as an important human pathogen and it remains among the top ten causes of mortality from an infectious disease. Group A Streptococcus throat carriage plays an important role in the development of infection and transmission to contacts. In Ethiopia, there is little information about screening of children for group A Streptococcus carriage.

Objective

This study was aimed to assess the magnitude of throat carriage, associated factors, and antimicrobial susceptibility pattern of group A Streptococcus among healthy school children in Jigjiga city, Eastern Ethiopia from 12 April to 27 May 2021.

Method

A cross-sectional study was conducted enrolled by simple random sampling. Data on socio-demographic and related characteristics were gathered using pretested structured questionnaire. The throat sample was collected from 462 healthy school children and immediately transported to Jigjiga University Sultan Sheik Hassan referral hospital laboratory for investigation. Identification of group A Streptococcus was done by colony characterstics, gram staining, catalase negativity, bacitracin sensitivity, and Pyrrolidonyl arylamidase tests. Antibiotic susceptibility test was done on Muller-Hinton agar containing 5% sheep blood by modified Kirby-Bauer disc diffusion method. The data were coded, cleaned, and entered onto EpiData Version 3.1 then exported to SPSS version 26.0 for analysis. Bivariate and multivariable logistic regression through adjusted odds ratio (AOR) was used to determine the relationship between culture-positivity rates of GAS and predictor variables. A p-value < 0.05 was taken as statistically significant on multivariable analysis.

Results

The overall prevalence of group A Streptococcus throat culture rate was 10.6% (95%CI; 8.1%—13.7%). Previous family member who had a sore throat, children living with larger families (more than 11 members), and children living with non-immediate families were significantly associated with culture-positivity rates of GAS. Children who live with a family member with a sore throat compared with those who lived with in a family with no history of sore throat (AOR = 2.51; 95%CI 1.09–5.73), children who live with a large family comared to children living in families with less members (AOR = 4.64; 95% CI 1.53–14.1), and children who live with non-immediate families compared to children living with their mothers (AOR = 3.65; 95% CI 1.39 – 9.61), showed significant association with group A Streptococcus carriage rate. Resistance to all other antibiotics tested was low (< 5%). Multidrug resistance was found in 4.1% of isolates.

Conclusion

The present study showed 10.6% throat carriage of group A Streptococcus. Family member with a sore throat, having a large family, and living with non-immediate families have all been identified as independent predictors of carriage prevalence.

Opsonophagocytic Killing Assay to Measure Anti-Group A Streptococcus Antibody Functionality in Human Serum

The opsonophagocytic killing assay (OPKA) is designed to measure the functionality of strain-specific antibodies and, therefore, assess protective immunity or the immunogenicity of Group A Streptococcus (GAS) (type A Streptococcus pyogenes) vaccines. Opsonization of GAS for phagocytosis is an important mechanism by which antibodies protect against disease in vivo. The Opsonophagocytic Index or Opsonic Index (OI) is the estimated dilution of antisera that kills 50% of the target bacteria. Here, we describe the protocol of the standardized GAS OPKA developed by Jones et al., 2018.