Factors associated with Group A Streptococcus emm type diversification in a large urban setting in Brazil: a cross-sectional study

The Role of Physical Examination and Clinical Scores in Distinguishing Streptococcal Colonization from Pharyngitis in Pediatric Patients: Insights from a Common Clinical Scenario

The accurate differentiation between asymptomatic carriage with group A streptococcus (GAS) and active streptococcal pharyngitis is a complex task with important clinical and public health implications. This work aims to highlight the key strategies necessary for optimizing the diagnostic and therapeutic management of pediatric pharyngitis. Clinical scores are essential tools for improving diagnostic accuracy. When combined with laboratory tests such as throat cultures and rapid antigen detection tests, these systems enable effective risk stratification of patients, supporting more precise treatment decisions. In addition to diagnostic strategies, the article underscores the importance of patient-centered communication, particularly with the families of pediatric patients. Clear, empathetic discussions about the condition, diagnostic rationale, and treatment plan help foster trust, enhance adherence to medical recommendations, and reduce anxiety related to potential complications. A critical outcome of these combined strategies is the reduction of unnecessary antibiotic use, which plays a pivotal role in preventing both overdiagnosis and overprescription. This, in turn, mitigates the growing threat of antimicrobial resistance, one of the most significant global health challenges. By integrating clinical expertise, standardized protocols, and effective communication, healthcare providers can promote judicious and effective management of streptococcal pharyngitis or asymptomatic carriage, contributing to improved individual and population health outcomes.

Global Streptococcus pyogenes strain diversity, disease associations, and implications for vaccine development: a systematic review

The high strain diversity of Streptococcus pyogenes serves as a major obstacle to vaccine development against this leading global pathogen. We did a systematic review of studies in PubMed, MEDLINE, and Embase that reported the global distribution of S pyogenes emm-types and emm-clusters from Jan 1, 1990, to Feb 23, 2023. 212 datasets were included from 55 countries, encompassing 74 468 bacterial isolates belonging to 211 emm-types. Globally, an inverse correlation was observed between strain diversity and the UNDP Human Development Index (HDI; r=-0·72; p<0·0001), which remained consistent upon subanalysis by global region and site of infection. Greater strain diversity was associated with a lower HDI, suggesting the role of social determinants in diseases caused by S pyogenes. We used a population-weighted analysis to adjust for the disproportionate number of epidemiological studies from high-income countries and identified 15 key representative isolates as vaccine targets. Strong strain type associations were observed between the site of infection (invasive, skin, and throat) and several streptococcal lineages. In conclusion, the development of a truly global vaccine to reduce the immense burden of diseases caused by S pyogenes should consider the multidimensional diversity of the pathogen, including its social and environmental context, and not merely its geographical distribution.

Prevalence and antibiotics susceptibility profiles of Streptococcus pyogenes among pediatric patients with acute pharyngitis at Felege Hiwot Comprehensive Specialized Hospital, Northwest Ethiopia

BACKGROUND

Streptococcus pyogenes (S. pyogenes) is a Gram positive bacterium which is a leading cause of pharyngitis, skin and soft tissue infection and post streptococcal syndromes. Due to lack of β-lactamase enzyme production, it was considered universally susceptible to penicillin group and later generation of β-lactam antibiotics. As such, empirical treatment was common which might leads to development of antibiotics resistance. Therefore, the aims of this study were to determine the prevalence, antibiotics susceptibility profile; and associated factors of S. pyogenes among pediatric patients with acute pharyngitis in Felege Hiwot Comprehensive Specialized Hospital (FHCSH), Northwest Ethiopia.

METHODS

Hospital based cross-sectional study was carried out on 154 pediatric patients, whose age ranged from 0 to 18 years old using consecutive convenient sampling technique from 1st February to 19th June 2020 at FHCSH. S. pyogenes were identified by throat swab culture on 5% sheep blood agar with an overnight incubation at 37 °C in candle jar containing 5% CO2. Gram stain, catalase test and bacitracin test were used to identify S. pyogenes. Then,the data were entered into EpiData version 3.1 and analyzed by SPSS version 20 software. Finally, stepwise, bivariable and multivariable logistic regressions were carried out for identifyying factors having significant ssociation (p<0.05) with  acute pharyngitis.  RESULTS: From the total throat swabs, 14 (9.1%) with (95% CI; 4.5-14.3) were culture positive for S. pyogenes. From these, all isolates were sensitive to penicillin and ampicillin. On the otherhand, 4 (35.7%), 4 (35.5%), 3 (21.4%), 2 (14.3%), 1 (7.1%), 7 (50.0%) and 1 (7.1%) isolates were resistant for ceftriaxone, vancomycin, erythromycin, tetracycline, chloramphenicol, clindamycin and levofloxacin, respectively. The presence of any smoker in home showed significant association with S. pyogenes acute pharyngitis. Furthermore, having tender lymphadenopathy and recurrence were clinical predictors for S. pyogenes acute pharyngitis (P < 0.05).

CONCLUSION

The prevalence of S. pyogenes was guaged at 9.1% which is considered as low prevalence. All S. pyogenes isolats remain sensitive to penicillin. However, resistance was reported to clindamycin 7 (50.0%), ceftriaxone 5 (35.7%) and erythromycin 3 (21.4%). The current practice of giving erythromycin, clindamycin instead of penicillin and ampicillin is againest the microbiology result. Therefore, current empirical treatment of acute pharyngitis shall take in to account the current evidences. Continuous surveillance of antibiotics resistance pattern of S. pyogenes for acute pharyngitis must be strengthen to improve the use of antibiotics in hospitals.

Naturally Acquired Protection Against Upper Respiratory Symptoms Involving Group A Streptococcus in a Longitudinal Cohort Study

BACKGROUND

Pharyngitis due to group A Streptococcus (GAS) represents a major cause of outpatient visits and antibiotic use in the United States. A leading vaccine candidate targets 30 of the > 200 emm types of GAS. We aimed to assess natural protection conferred by GAS against respiratory symptoms.

METHODS

In a 5-year study among school-aged children in Pittsburgh, Pennsylvania, pharyngeal cultures were obtained from children at 2-week intervals, and active surveillance was conducted for respiratory illnesses. We assessed protection via the relative odds of previous detection of homologous strains (defined by field-inversion gel electrophoresis banding pattern), emm types, and emm clusters at visits where GAS was detected with symptoms, vs visits where GAS was detected without symptoms. We used a cluster bootstrap of children to adjust estimates for repeated sampling.

RESULTS

At visits where previously detected GAS emm types were identified, we estimated 81.8% (95% confidence interval [CI], 67.1%-91.7%) protection against typical pharyngitis symptoms among children reacquiring the same strain, and 94.5% (95% CI, 83.5%-98.6%) protection among children acquiring a distinct strain. We estimated 77.1% (95% CI, 33.7%-96.3%) protection against typical symptoms among children acquiring partially heterologous emm types belonging to a previously detected emm cluster. Protection was evident after both symptomatic and asymptomatic detections of GAS. We did not identify strong evidence of protection against atypical respiratory symptoms.

CONCLUSIONS

Within a 5-year longitudinal study, previous detection of GAS emm types was associated with protection against typical symptoms when homologous strains were subsequently detected. Naturally acquired protection against partially heterologous types suggests that emm type-based vaccines may have broader strain coverage than what has been previously assumed.

A brief review on Group A Streptococcus pathogenesis and vaccine development

Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a Gram-positive human-exclusive pathogen, responsible for more than 500 000 deaths annually worldwide. Upon infection, GAS commonly triggers mild symptoms such as pharyngitis, pyoderma and fever. However, recurrent infections or prolonged exposure to GAS might lead to life-threatening conditions. Necrotizing fasciitis, streptococcal toxic shock syndrome and post-immune mediated diseases, such as poststreptococcal glomerulonephritis, acute rheumatic fever and rheumatic heart disease, contribute to very high mortality rates in non-industrialized countries. Though an initial reduction in GAS infections was observed in high-income countries, global outbreaks of GAS, causing rheumatic fever and acute poststreptococcal glomerulonephritis, have been reported over the last decade. At the same time, our understanding of GAS pathogenesis and transmission has vastly increased, with detailed insight into the various stages of infection, beginning with adhesion, colonization and evasion of the host immune system. Despite deeper knowledge of the impact of GAS on the human body, the development of a successful vaccine for prophylaxis of GAS remains outstanding. In this review, we discuss the challenges involved in identifying a universal GAS vaccine and describe several potential vaccine candidates that we believe warrant pursuit.

A Review of Streptococcus pyogenes: Public Health Risk Factors, Prevention and Control

Streptococcus pyogenes, (colloquially named "group A streptococcus" (GAS)), is a pathogen of public health significance, infecting 18.1 million people worldwide and resulting in 500,000 deaths each year. This review identified published articles on the risk factors and public health prevention and control strategies for mitigating GAS diseases. The pathogen causing GAS diseases is commonly transmitted via respiratory droplets, touching skin sores caused by GAS or through contact with contaminated material or equipment. Foodborne transmission is also possible, although there is need for further research to quantify this route of infection. It was found that GAS diseases are highly prevalent in developing countries, and among indigenous populations and low socioeconomic areas in developed countries. Children, the immunocompromised and the elderly are at the greatest risk of S. pyogenes infections and the associated sequelae, with transmission rates being higher in schools, kindergartens, hospitals and residential care homes. This was attributed to overcrowding and the higher level of social contact in these settings. Prevention and control measures should target the improvement of living conditions, and personal and hand hygiene. Adherence to infection prevention and control practices should be emphasized in high-risk settings. Resource distribution by governments, especially in developed countries, should also be considered.

The Path to Group A Streptococcus Vaccines: World Health Organization Research and Development Technology Roadmap and Preferred Product Characteristics

Group A Streptococcus (GAS) infections result in a considerable underappreciated burden of acute and chronic disease globally. A 2018 World Health Assembly resolution calls for better control and prevention. Providing guidance on global health research needs is an important World Health Organization (WHO) activity, influencing prioritization of investments. Here, the role, status, and directions in GAS vaccines research are discussed. WHO preferred product characteristics and a research and development technology roadmap, briefly presented, offer an actionable framework for vaccine development to regulatory and policy decision making, availability, and use. GAS vaccines should be considered for global prevention of the range of clinical manifestations and associated antibiotic use. Impediments related to antigen diversity, safety concerns, and the difficulty to establish vaccine efficacy against rheumatic heart disease are discussed. Demonstration of vaccine efficacy against pharyngitis and skin infections constitutes a key near-term strategic goal. Investments and collaborative partnerships to diversify and advance vaccine candidates are needed.

Complete Genome Sequences of Two Strains of Streptococcus pyogenes Belonging to an Emergent Clade of the Genotype emm 89 in Brittany, France

The frequency of infections due to Streptococcus pyogenes M/emm89 strains is increasing, presumably due to the emergence of a genetically distinct clone. We sequenced two emm89 strains isolated in Brittany, France, in 2009 and 2010 from invasive and noninvasive infections, respectively. Both strains belong to a newly emerged emm89 clade 3 clone.

The frequency of infections due to Streptococcus pyogenes M/emm89 strains is increasing, presumably due to the emergence of a genetically distinct clone. We sequenced two emm89 strains isolated in Brittany, France, in 2009 and 2010 from invasive and noninvasive infections, respectively. Both strains belong to a newly emerged emm89 clade 3 clone.

Differences in gram-positive bacterial colonization and antimicrobial resistance among children in a high income inequality setting

Background

Staphylococcus aureus and beta-hemolytic streptococci (BHS) diseases disproportionately affect populations in middle/low-income countries. To assess if this disparity is reflected in colonization by these organisms, we compared their colonization frequency among children from different socioeconomic status (SES) communities in a city with high income inequality.

Methods

Between May–August 2014, we collected nasal and throat swabs to investigate S. aureus and BHS colonization among children who attended private and public pediatric clinics. Patients were classified as high SES, middle/low SES, and slum residents. We investigated the antimicrobial resistance profile, the SCCmec types and the presence of PVL genes among methicillin-resistant S. aureus (MRSA). We also examined the antimicrobial resistance profile and serogroups of BHS.

Results

Of 598 children, 221 (37%) were colonized with S. aureus, of which 49 (22%) were MRSA. MRSA colonization was higher in middle/low SES (n = 18; 14%) compared with high SES (n = 17; 6%) and slum (n = 14; 8%) residents (p = 0.01). All MRSA strains were susceptible to clindamycin, nitrofurantoin, and rifampin. The highest non-susceptibility frequency (42.9%) was observed to erythromycin. SCCmec type V was only found in isolates from high SES children; types I and II were found only in middle/low SES children. Ten (20%) MRSA isolates carried PVL genes. Twenty-four (4%) children were BHS carriers. All BHS (n = 8) found in high SES children and six (67%) isolates from slum patients belonged to group A. All group B streptococci were from middle/low SES children, corresponding to five (71%) of the seven BHS isolated in this group. BHS isolates were susceptible to all drugs tested.

Conclusions

Children from different SES communities had distinct bacterial colonization profiles, including MRSA carriage. Public health officials/researchers should consider SES when assessing disease transmission and control measures.

Clinical Screening Tools to Diagnose Group A Streptococcal Pharyngotonsillitis in Primary Care Clinics to Improve Prescribing Habits

This review highlights the clinical scoring tools used for the management of acute pharyngotonsillitis in primary care clinics. It will include the prevalence of group A pharyngotonsillitis among children and adults worldwide and the selective tests employed for diagnosing group A streptococcal pharyngotonsillitis. Pharyngotonsillitis is one of the common reasons for visits to primary care clinics worldwide, and physicians tend to prescribe antibiotics according to the clinical symptoms, which leads to overprescribing antibiotics. This in turn may lead to serious health impacts and severe reactions and may promote antibiotic resistance. These significantly add on to the health care costs. The available information from health organisations and previous studies has indicated the need to manage the diagnosis of pharyngotonsillitis to improve prescribing habits in primary care clinics.

Comparison Between Different Strategies of Rheumatic Heart Disease Echocardiographic Screening in Brazil: Data From the PROVAR (Rheumatic Valve Disease Screening Program) Study

Background

Considering the limited accuracy of clinical examination for early diagnosis of rheumatic heart disease (RHD), echocardiography has emerged as an important epidemiological tool. The ideal setting for screening is yet to be defined. We aimed to evaluate the prevalence and pattern of latent RHD in schoolchildren (aged 5–18 years) and to compare effectiveness of screening between public schools, private schools, and primary care centers in Minas Gerais, Brazil.

Methods and Results

The PROVAR (Rheumatic Valve Disease Screening Program) study uses nonexperts and portable and handheld devices for RHD echocardiographic screening, with remote interpretation by telemedicine, according to the 2012 World Heart Federation criteria. Compliance with study consent and prevalence were compared between different screening settings, and variables associated with RHD were analyzed. In 26 months, 12 048 students were screened in 52 public schools (n=10 901), 2 private schools (n=589), and 3 primary care centers (n=558). Median age was 12.9 years, and 55.4% were girls. Overall RHD prevalence was 4.0% borderline (n=486) and 0.5% definite (n=63), with statistically similar rates between public schools (4.6%), private schools (3.5%), and primary care centers (4.8%) (P=0.24). The percentage of informed consents signed was higher in primary care centers (84.4%) and private schools (66.9%) compared with public schools (38.7%) (P<0.001). Prevalence was higher in children ≥12 years (5.3% versus 3.1%; P<0.001) and girls (4.9% versus 4.0%; P=0.02). Only age (odds ratio, 1.12; 95% confidence interval, 1.09–1.17; P<0.001) was independently associated with RHD.

Conclusions

RHD screening in primary care centers seems to achieve higher coverage rates. Prevalence among schoolchildren is significantly high, with rates higher than expected in private schools of high‐income areas. These data are important for the formulation of public policies to confront RHD.

Streptococcus pyogenes strains in Sao Paulo, Brazil: molecular characterization as a basis for StreptInCor coverage capacity analysis

BACKGROUND

Several human diseases are caused by Streptococcus pyogenes, ranging from common infections to autoimmunity. Characterization of the most prevalent strains worldwide is a useful tool for evaluating the coverage capacity of vaccines under development. In this study, a collection of S. pyogenes strains from Sao Paulo, Brazil, was analyzed to describe the diversity of strains and assess the vaccine coverage capacity of StreptInCor.

METHODS

Molecular epidemiology of S. pyogenes strains was performed by emm-genotyping the 229 isolates from different clinical sites, and PCR was used for superantigen profile analysis. The emm-pattern and tissue tropism for these M types were also predicted and compared based on the emm-cluster classification.

RESULTS

The strains were fit into 12 different emm-clusters, revealing a diverse phylogenetic origin and, consequently, different mechanisms of infection and escape of the host immune system. Forty-eight emm-types were distinguished in 229 samples, and the 10 most frequently observed types accounted for 69 % of all isolates, indicating a diverse profile of circulating strains comparable to other countries under development. A similar proportion of E and A-C emm-patterns were observed, whereas pattern D was less frequent, indicating that the strains of this collection primarily had a tissue tropism for the throat. In silico analysis of the coverage capacity of StreptInCor, an M protein-conserved regionally based vaccine candidate developed by our group, had a range of 94.5 % to 59.7 %, with a mean of 71.0 % identity between the vaccine antigen and the predicted amino acid sequence of the emm-types included here.

CONCLUSIONS

This is the first report of S. pyogenes strain characterization in Sao Paulo, one of the largest cities in the world; thus, the strain panel described here is a representative sample for vaccine coverage capacity analysis. Our results enabled evaluation of StreptInCor candidate vaccine coverage capacity against diverse M-types, indicating that the vaccine candidate likely would induce protection against the diverse strains worldwide.

Streptococcal pharyngitis in schoolchildren in Bamako, Mali

BACKGROUND

Group A streptococcus (GAS) pharyngitis is associated with high rates of rheumatic heart disease in developing countries. We sought to identify guidelines for empiric treatment of pharyngitis in low-resource settings. To inform the design of GAS vaccines, we determined the emm types associated with pharyngitis among African schoolchildren.

METHODS

Surveillance for pharyngitis was conducted among children 5-16 years of age attending schools in Bamako, Mali. Students were encouraged to visit a study clinician when they had a sore throat. Enrollees underwent evaluation and throat swab for isolation of GAS. Strains were emm typed by standard methods.

RESULTS

GAS was isolated from 449 (25.5%) of the 1,759 sore throat episodes. Painful cervical adenopathy was identified in 403 children (89.8%) with GAS infection and was absent in 369 uninfected children (28.2%). Emm type was determined in 396 (88.2%) of the 449 culture-positive children; 70 types were represented and 14 types accounted for 49% of isolates. Based on the proportion of the 449 isolates bearing emm types included in the 30-valent vaccine (31.0%) plus nonvaccine types previously shown to react to vaccine-induced bactericidal antibodies (44.1%), the vaccine could protect against almost 75% of GAS infections among Bamako schoolchildren.

CONCLUSIONS

Two promising strategies could reduce rheumatic heart disease in low-resource settings. Administering antibiotics to children with sore throat and tender cervical adenopathy could treat most GAS-positive children while reducing use of unnecessary antibiotics for uninfected children. Broad coverage against M types associated with pharyngitis in Bamako schoolchildren might be achieved with the 30-valent GAS vaccine under development.

Antimicrobial susceptibility patterns, emm type distribution and genetic diversity of Streptococcus pyogenes recovered in Brazil

Streptococcus pyogenes is responsible for a variety of infectious diseases and immunological complications. In this study, 91 isolates of S. pyogenes recovered from oropharynx secretions were submitted to antimicrobial susceptibility testing, emm typing and pulsed-field gel electrophoresis (PFGE) analysis. All isolates were susceptible to ceftriaxone, levofloxacin, penicillin G and vancomycin. Resistance to erythromycin and clindamycin was 15.4%, which is higher than previous reports from this area, while 20.9% of the isolates were not susceptible to tetracycline. The macrolide resistance phenotypes were cMLSB (10) and iMLSB (4). The ermB gene was predominant, followed by the ermA gene. Thirty-two emm types and subtypes were found, but five (emm1, emm4, emm12, emm22, emm81) were detected in 48% of the isolates. Three new emm subtypes were identified (emm1.74, emm58.14, emm76.7). There was a strong association between emm type and PFGE clustering. A variety of PFGE profiles as well as emm types were found among tetracycline and erythromycin-resistant isolates, demonstrating that antimicrobial resistant strains do not result from the expansion of one or a few clones. This study provides epidemiological data that contribute to the development of suitable strategies for the prevention and treatment of such infections in a poorly studied area.

Distribution of superantigens in group A streptococcal isolates from Salvador, Brazil

BACKGROUND

Group A streptococcus (GAS) causes invasive disease, superficial disease, and can asymptomatically colonize humans. Superantigens are one virulence factor found in GAS. Previous studies found associations between the genes that encode superantigens and emm type of GAS. It is unknown if these associations are due to underlying biological factors that limit the distribution of superantigens or, alternatively, if these associations are due to the expansion of local GAS linages where these studies took place. To further address this question we screened GAS isolates collected from Salvador, Brazil for 11 known superantigen genes.

METHODS

Seventy-seven GAS isolates were screened by PCR for superantigen genes. These superantigen genes were speA, speC, speG, speH, speI, speJ, speK, speL, speM, ssa, and smeZ. We used Fisher's two-sided exact test to identify associations between superantigens and GAS emm type. We then compared our results to previous reports of superantigen prevalence and superantigen association with emm type.

RESULTS

In our collection we found several emm type and superantigen genotype combinations that have previously been reported in isolates from Europe and Australia. We also found that speA was significantly associated with emm type 1, and that speC was significantly associated with emm type 12.

CONCLUSIONS

Our study reports superantigen genotypes of GAS from a region of the world that is lacking this information. We found evidence of common GAS superantigen genotypes that are spread worldwide as well as novel superantigen genotypes that, so far, are unique to Brazil.

Analysis of the coverage capacity of the StreptInCor candidate vaccine against Streptococcus pyogenes

Streptococcus pyogenes is responsible for infections as pharyngitis, sepsis, necrotizing fasciitis and streptococcal toxic shock syndrome. The M protein is the major bacterial antigen and consists of both polymorphic N-terminal portion and a conserved region. In the present study, we analyzed the in vitro ability of StreptInCor a C-terminal candidate vaccine against S. pyogenes to induce antibodies to neutralize/opsonize the most common S. pyogenes strains in Sao Paulo by examining the recognition by sera from StreptInCor immunized mice. We also evaluated the presence of cross-reactive antibodies against human heart valve tissue. Anti-StreptInCor antibodies were able to neutralize/opsonize at least 5 strains, showing that immunization with StreptInCor is effective against several S. pyogenes strains and can prevent infection and subsequent sequelae without causing autoimmune reactions.