Epidemiological and molecular analysis of Streptococcus pyogenes isolates causing invasive disease in Spain (1998-2009): comparison with non-invasive isolates

Epidemiology and clinical features of Streptococcus pyogenes bloodstream infections in children in Madrid, Spain

Studies have shown increased invasive Group A Streptococcus (GAS) disease, including bloodstream infections (GAS-BSI). However, the epidemiological data of GAS-BSI are limited in children. We aimed to describe GAS-BSI in children in Madrid, over 13 years (2005-2017). Multicenter retrospective cohort study from 16 hospitals from Madrid, Spain. Epidemiology, symptomatology, laboratory, treatment, and outcome of GAS-BSI in children ≤ 16 years were analyzed. 109 cases of GAS-BSI were included, with incidence rate of 4.3 episodes/100,000 children attended at the emergency department/year. We compared incidence between two periods (P1: 2005-June 2011 vs P2: July 2011-2017) and observed a non-significant increase along the study period (annual percentage change: + 6.0% [95%CI: -2.7, + 15.4]; p = 0.163). Median age was 24.1 months (IQR: 14.0-53.7), peaking during the first four years of life (89/109 cases; 81.6%). Primary BSI (46.8%), skin and soft tissue (21.1%), and osteoarticular infections (18.3%) were the most common syndromes. We compared children with primary BSI with those with a known source and observed that the former had shorter hospital stay (7 vs. 13 days; p = 0.003) and received intravenous antibiotics less frequently (72.5% vs. 94.8%; p = 0.001) and for shorter duration of total antibiotic therapy (10 vs. 21 days; p = 0.001). 22% of cases required PICU admission. Factors associated with severity were respiratory distress, pneumonia, thrombocytopenia, and surgery, but in multivariate analysis, only respiratory distress remained significant (adjusted OR:9.23 [95%CI: 2.16-29.41]). Two children (1.8%) died.   Conclusion: We observed an increasing, although non-significant, trend of GAS-BSI incidence within the study. Younger children were more frequently involved, and primary BSI was the most common and less severe syndrome. PICU admission was frequent, being respiratory distress the main risk factor. What is known: • In recent decades, several reports have shown a worldwide increase in the incidence of invasive Group A streptococcal disease (GAS), including bloodstream infection (BSI). Recently, there have been a few reports showing an increase in severity as well. • There needs to be more information on the epidemiology in children since most studies predominantly include adults. What is new: • This study, carried out in children with GAS-BSI in Madrid, shows that GAS-BSI affects mostly younger children, with a broad spectrum of manifestations, needing PICU admission frequently. Respiratory distress was the leading risk factor for severity, whereas primary BSI seemed to be less severe. • We observed an increasing, although non-significant, trend of GAS-BSI incidence in recent years (2005-2017).

National Surveillance of Tetracycline, Erythromycin, and Clindamycin Resistance in Invasive Streptococcus pyogenes: A Retrospective Study of the Situation in Spain, 2007-2020

BACKGROUND

This work reports on antimicrobial resistance data for invasive Streptococcus pyogenes in Spain, collected by the 'Surveillance Program for Invasive Group A Streptococcus', in 2007-2020.

METHODS

emm typing was determined by sequencing. Susceptibility to penicillin, tetracycline, erythromycin, and clindamycin was determined via the E-test. tetM, tetO, msrD, mefA, ermB, ermTR, and ermT were sought by PCR. Macrolide-resistant phenotypes (M, cMLSB, and iMLSB) were detected using the erythromycin-clindamycin double-disk test. Resistant clones were identified via their emm type, multilocus sequence type (ST), resistance genotype, and macrolide resistance phenotype.

RESULTS

Penicillin susceptibility was universal. Tetracycline resistance was recorded for 237/1983 isolates (12.0%) (152 carried only tetM, 48 carried only tetO, and 33 carried both). Erythromycin resistance was detected in 172/1983 isolates (8.7%); ermB was present in 83, mefA in 58, msrD in 51, ermTR in 46, and ermT in 36. Clindamycin resistance (methylase-mediated) was present in 78/1983 isolates (3.9%). Eight main resistant clones were identified: two that were tetracycline-resistant only (emm22/ST46/tetM and emm77/ST63/tetO), three that were erythromycin-resistant only (emm4/ST39/mefA-msrD/M, emm12/ST36/mefA-msrD/M, and emm28/ST52/ermB/cMLSB), and three that were tetracycline-erythromycin co-resistant (emm11/ST403/tetM-ermB/cMLSB, emm77/ST63/tetO-ermTR/iMLSB, and emm77/ST63/tetM-tetO-ermTR/iMLSB).

CONCLUSIONS

Tetracycline, erythromycin, and clindamycin resistance rates declined between 2007 and 2020. Temporal variations in the proportion of resistant clones determined the change in resistance rates.

An Overview of Macrolide Resistance in Streptococci: Prevalence, Mobile Elements and Dynamics

Streptococcal infections are usually treated with beta-lactam antibiotics, but, in case of allergic patients or reduced antibiotic susceptibility, macrolides and fluoroquinolones are the main alternatives. This work focuses on studying macrolide resistance rates, genetic associated determinants and antibiotic consumption data in Spain, Europe and also on a global scale. Macrolide resistance (MR) determinants, such as ribosomal methylases (erm(B), erm(TR), erm(T)) or active antibiotic efflux pumps and ribosomal protectors (mef(A/E)-mrs(D)), are differently distributed worldwide and associated with different clonal lineages and mobile genetic elements. MR rates vary together depending on clonal dynamics and on antibiotic consumption applying selective pressure. Among Streptococcus, higher MR rates are found in the viridans group, Streptococcus pneumoniae and Streptococcus agalactiae, and lower MR rates are described in Streptococcus pyogenes. When considering different geographic areas, higher resistance rates are usually found in East-Asian countries and milder or lower in the US and Europe. Unfortunately, the availability of data varies also between countries; it is scarce in low- and middle- income countries from Africa and South America. Thus, surveillance studies of macrolide resistance rates and the resistance determinants involved should be promoted to complete global knowledge among macrolide resistance dynamics.

Characterization of group A beta-haemolytic streptococcus with mucoid phenotype isolated in a tertiary hospital

INTRODUCTION

The objective of this study is to characterize Streptococcus pyogenes isolates with a mucoid phenotype and to compare them with non-mucoid isolates obtained between April and August 2016.

MATERIAL AND METHODS

Identification and antimicrobial susceptibility were performed in all isolates. The emm type and exotoxin genes speA, speB, speC, speF, speG, speH, speJ, speZ and ssa were analyzed. Clinical and demographic data were collected.

RESULTS

From 96 isolates analyzed, 47% had a mucoid phenotype and 95.5% of them presented speA-speB-speF-speG-ssa genes and emm3 genotype. The main clinical manifestation was pharyngotonsillitis (77.1%) evolving to scarlet fever in 67.5% of the cases.

CONCLUSION

This study describes the circulation of a mucoid phenotype strain with a speA-speB-speF-speG-ssa toxin profile and emm3.1 genotype considered one of the most frequent and virulent of SGA.

Invasive Streptococcus pyogenes disease in Spain: a microbiological and epidemiological study covering the period 2007-2019

The aim of this study is to present the first nationwide microbiological and epidemiological study of invasive group A Streptococcus (iGAS) disease in Spain. One thousand eight hundred ninety-three iGAS isolates were analyzed over 2007-2019. emm typing was performed by sequencing the gene's variable 5' end, exotoxin genes were identified by PCR, and antimicrobial susceptibility explored via the E test and disk diffusion. Five hundred twenty-three isolates were associated with sepsis, 292 with cellulitis, 232 with scarlet fever, 153 with pneumonia, 141 with streptococcal toxic shock syndrome, and 94 with necrotizing fasciitis. The most prevalent emm types were emm1 (449/1893 isolates), emm89 (210/1893), emm3 (208/1893), emm4 (150/1893), emm12 (112/1893) emm6 (107/1893), emm87 (89/1893), emm28 (88/1893), emm75 (78/1893), emm77 (78/1893), emm11 (58/1893), and emm22 (35/1893). emm1, emm3, emm4, and emm6 were the predominant types affecting children (mostly respiratory infections), while emm11, emm77, and emm89 prevailed in the elderly (mostly skin infections). Each emm type was associated with one or more exotoxin gene (spe, sme, and ssa) profiles. speA was detected in 660 isolates, speB in 1829, speC in 1014, speF in 1826, speG in 1651, speJ in 716, speH in 331, smeZ in 720, and ssa in 512. Isolates with speA were associated with the most severe infections. Penicillin susceptibility was universal. Two hundred twenty-four isolates were resistant to tetracycline, 169 to erythromycin, and 81 to clindamycin. Tetracycline, erythromycin, and clindamycin resistance rates declined over the study period. The above information could serve as the basis for continued surveillance efforts designed to control disease cause by this bacterium.

Characterization of group A beta-haemolytic streptococcus with mucoid phenotype isolated in a tertiary hospital

INTRODUCTION

The objective of this study is to characterize Streptococcus pyogenes isolates with a mucoid phenotype and to compare them with non-mucoid isolates obtained between April and August 2016.

MATERIAL AND METHODS

Identification and antimicrobial susceptibility were performed in all isolates. The emm type and exotoxin genes speA, speB, speC, speF, speG, speH, speJ, speZ and ssa were analyzed. Clinical and demographic data were collected.

RESULTS

From 96 isolates analyzed, 47% had a mucoid phenotype and 95.5% of them presented speA-speB-speF-speG-ssa genes and emm3 genotype. The main clinical manifestation was pharyngotonsillitis (77.1%) evolving to scarlet fever in 67.5% of the cases.

CONCLUSION

This study describes the circulation of a mucoid phenotype strain with a speA-speB-speF-speG-ssa toxin profile and emm3.1 genotype considered one of the most frequent and virulent of SGA.

Beta-Haemolytic Group A, C and G Streptococcal Infections in Southern Hungary: A 10-Year Population-Based Retrospective Survey (2008-2017) and a Review of the Literature

Introduction

Pyogenic β-hemolytic streptococci (including Group A, C and G Streptococcus) are some of the most important Gram-positive bacterial pathogens in human medicine. Although effective therapy is available, invasive streptococcal infections are associated with a significant disease burden.

Methods

In this retrospective study, the epidemiological characteristics of invasive Group A (iGAS) and Group C and G (iGCGS) streptococci, along with tonsillo-pharyngitis-causing pGAS and pGCGS infections, were assessed in Southern Hungary. A total of 1554 cases of streptococcal tonsillo-pharyngitis infections (26.5–44.1/100,000 persons, pGAS: 95.5%; n=1484) and 1104 cases of invasive streptococcal infections were detected (12.5–31.4/100,000 persons, iGAS: 77.9%; n=861).

Results

The average age of the affected patients in the various groups were the following: pGAS: 13.2±13.1 years, pGCGS: 21.0±15.0 years (p=0.039), iGAS: 49.1±12.8 years, iGCGS: 58.7±18.5 years (p>0.05). iGAS isolates originated from abscesses (47.1%), blood culture samples (24.1%), surgical samples (16.7%), biopsies (4.6%), pleural fluid (3.5%), pus (2.0%), synovial fluid (1.3%) and cerebrospinal fluid samples (0.7%). In contrast, iGCGS isolates mainly originated from blood culture samples (53.8%), abscesses (22.9%), surgical samples (12.3%), synovial fluid (5.1%), pleural fluid (3.7%), pus (1.8%) and cerebrospinal fluid samples (0.4%). All respective isolates were susceptible to benzyl-penicillin; overall resistance levels for erythromycin (10.5% for GAS, 21.4% for GCGS) and clindamycin (9.2% for GAS, 17.2% for GCGS) were significantly higher in GCGS isolates, while resistance levels for norfloxacin were higher in GAS isolates (13.5% for GAS, 6.9% for GCGS).

Conclusion

The rates of resistance to macrolides and clindamycin are a cause for concern (especially among GCGS isolates); however, resistance levels are still relatively low, compared to Southern European countries.

[Invasive Streptococcus pyogenes infections (2011-2018): EMM-type and clinical presentation]

INTRODUCTION

Streptococcus pyogenes (S. pyogenes) is an important human pathogen that is responsible for a broad range of infections, from uncomplicated to more severe and invasive diseases with high morbidity/mortality. The M protein (emm type) is a critical virulence factor. Several studies have shown an increased incidence of invasive S. pyogenes disease. This was associated with an increase in the prevalence of M1 and M3 types, well-recognised virulent M types. The aim of the present study was to confirm the resurgence of invasive S. pyogenes disease during 2011-2018 and to identify the relationship between specific M types with disease presentation.

MATERIAL AND METHODS

Isolates were confirmed using standard techniques: colony morphology, β-haemolysis, biochemical tests, and agglutination with specific antisera (DiaMondiaL Strep Kit, DiaMondiaL, Langenhagen, Germany). The antibiotic sensitivity was performed using microdilution (Vitek®2 Compact, bioMeriéux, Inc., Durham, NC). Molecular analysis included the determination of the emm gene and superantigen profile.

RESULTS

A total of 29 invasive isolates were collected (2011-2018) from blood (16), pleural fluid (9), synovial fluid (3), and cerebrospinal fluid (1). One strain per year was isolated between 2011 and 2013, with 2, 5, 4, 6, and 9 strains being isolated between 2014 and 2018, respectively. The most frequent clinical presentations were bacteraemia and pneumonia (10 and 9 cases). The predominant types were M1 (11 isolates) and M3 (3 isolates). A correlation was found between M1 and M3 types, and pneumonia (6/7 cases) and deep soft tissue infections (3/3 cases).

CONCLUSIONS

An increased incidence of invasive S. pyogenes disease was observed during the study period, with M1 and M3 types being those most commonly isolated and associated with pneumonia and deep soft tissue infections.

Molecular Characterization of Streptococcus pyogenes Causing Invasive Disease in Pediatric Population in Spain A 12-year Study

OBJECTIVES

To perform a comprehensive description of the epidemiology of Streptococcus pyogenes invasive disease in the pediatric population in 2 regions of Spain (Catalonia and Gipuzkoa) through 12 years.

METHODS

All S. pyogenes isolates causing invasive disease in pediatric patients between 2005 and 2016 were included. The emm-type and the presence of 13 exotoxin genes (speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ, ssa and slo) were determined in all 93 available isolates and the Multi Locus Sequece Typing in 10% of isolates of each different emm-type.

RESULTS

Overall, 103 cases of S. pyogenes invasive infections were detected: 77 in Catalonia and 26 in Gipuzkoa, being 50.5% females. The incidence rate per 100,000 children was 2.5 for Gipuzkoa and 2.6 for Catalonia, with no significant temporal trends. The median age was 30 months. The most frequent clinical presentations were: pneumonia (26.2%), bacteremia/sepsis (23.3%), septic arthritis/osteomyelitis (22.3%), cellulitis/mastoiditis (12.6%) and meningitis (6.8%). Eight children developed streptococcal toxic shock syndrome. Nine cases were preceded by varicella infection. The associated mortality rate was 3.9%. Three isolates were resistant to erythromycin, being one of them also resistant to clindamycin and 4 isolates were resistant to levofloxacine. Forteen different emm-types were detected being emm1/ST28 (40.9%) the most frequent clone in both regions followed by emm12/ST36-ST242, emm6/ST382, emm3/ST15, emm75/ST150 and emm4/ST38-39. speA gene was only detected in emm1 and emm3 isolates. Eight exotoxins were enough to assign an emm-type with a very high degree of accuracy (95%). The 30-valent vaccine would include 96.8% of isolates.

Long-term, single-center surveillance of non-invasive group A streptococcal (GAS) infections, emm types and emm clusters

Group A streptococci (GAS) are among the most frequent pathogens in children. Many epidemiological studies focus on specific GAS infections (such as tonsillopharyngitis or invasive disease), on GAS carriers or on post-streptococcal sequelae. By comparison, reports on regional GAS characteristics, particularly circulating non-invasive GAS in Europe, are rare. In a monocentric study, all GAS isolated from pediatric patients at a tertiary care hospital over a 6-year period (2006-2012) were characterized. GAS emm types and clusters were determined. Associated patient data were analyzed. Five hundred sixty-six GAS strains were collected. GAS tonsillopharyngitis was most common (71.6%), followed by pyoderma (6.0%), otitis media (3.7%), perineal dermatitis (3.4%), and invasive infections (1.4%). Colonizing strains represented 13.6% of GAS. GAS emm12 was most prevalent among invasive and non-invasive isolates. Emm1, emm4, emm28, and emm89 were the most frequent non-invasive GAS strains. The emm E4 cluster was most common, followed by the A-C4, A-C3, and E1. Among the GAS infections, different emm types and clusters were identified, e.g., emm4 was more common among patients with scarlet fever. Three new emm subtypes were characterized: emm29.13, emm36.7, and emm75.5. This comprehensive review of a large, local GAS cohort points to the differences between and similarities among GAS genotypes and disease manifestations, while minimizing regional variations. Considerable deviation from previous epidemiological findings is described, especially regarding the frequent detection of emm1 and emm89 in non-invasive GAS infections. Periodic updates on molecular and epidemiological GAS characteristics are needed to track the multifaceted pathogenic potential of GAS.

[Invasive disease due to Streptococcus pyogenes: Changes in incidence and prognostic factors]

INTRODUCTION

Invasive group A streptococcal disease (iGASD) is a serious infection in children. Several studies have shown an increased incidence in the past years.

OBJECTIVE

To evaluate the characteristics and outcome of iGASD in children, and to determine changes in incidence or severity.

MATERIAL AND METHODS

A retrospective study was conducted on children≤16 years evaluated in a tertiary paediatric hospital in Madrid, and diagnosed with iGASD (June 2005-July 2013). An analysis was made of the demographics, symptomatology, microbiology, and treatment. The changes throughout the period studied were evaluated, as well as parameters associated with disease severity.

RESULTS

The study included a total of 55 children with iGASD, with 33 (60%) females, and a median age of 48.5 (20.5-88.9) months. The most frequent clinical syndromes were cellulitis/subcutaneous abscess (21.8%), ENT abscess (20%), pneumonia (16.4%), osteoarticular infection (16.4%), and mastoiditis (12.7%). The incidence of iGASD (cases/10⁵ emergencies/year) increased from 5.6 (4.2-7.2) between June 2005-May 2009 to 18.9 (15.1-26) between June 2009-May 2013; P=.057. Surgery and admission to PICU was required by 35 (63.6%) and 10 (18.2%) patients, respectively. Children in PICU were younger (26.5 vs 52.6 months, P=.116), had a higher C-reactive protein (24.5 vs 10.7mg/dl, P<.001) and higher frequency of pneumonia (60 vs 7%, P<.001). In the multivariate analysis, only C-reactive protein was a risk factor for admission to PICU (OR: 1.14 [1.004-1.286], P=.04). There were no sequelae.

CONCLUSIONS

An increased incidence of iGASD was observed in the children in this study. Lower age, pneumonia, and higher C-reactive protein were associated with disease severity in this series.

Epidemiology of an upsurge of invasive group A streptococcal infections in Ireland, 2012-2015

OBJECTIVES

Group A streptococcus (GAS) is responsible for mild to very severe disease. The epidemiology of an upsurge in invasive GAS (iGAS) infections in Ireland, 2012-2015 was investigated.

METHODS

Epidemiological typing of iGAS (n = 473) isolates was performed and compared to non-invasive (n = 517) isolates. Clinical data of notified iGAS was obtained from the national infectious disease information system.

RESULTS

Annual incidences of iGAS cases (n = 561) were 2.33-3.66 per 100,000 population. Bacteraemia was the most common clinical presentation (75%) followed by focus without bacteraemia (19%) and necrotizing faciitis (7%). Streptococcal toxic shock syndrome occurred in 19% of presentations. The main invasive emm types in rank order were emm1, emm3, emm28, emm12 and emm89 whereas emm4, emm28, emm3, emm12, emm89 and emm1 predominated in non-invasive infections. Invasive emm1 and emm3 showed annual fluctuations (15-48% and 4-37%, respectively) and predominated in most clinical presentations of iGAS. Superantigens speA, speG, speJ was associated with iGAS disease and, speC, speI and ssa with non-invasive infections. There was 4.3% erythromycin and 5.6% tetracycline resistance. The main resistant types were emm11, emm28 and emm77.

CONCLUSIONS

Cyclic increases in emm1 and emm3 occurred during the iGAS upsurge. Continued surveillance of GAS is therefore essential given the epidemiological changes that occur in a short time period.

Prevalent emm Types among Invasive GAS in Europe and North America since Year 2000

BACKGROUND

Streptococcus pyogenes or group A streptococcus (GAS) is an important human pathogen responsible for a broad range of infections, from uncomplicated to more severe and invasive diseases with high mortality and morbidity. Epidemiological surveillance has been crucial to detect changes in the geographical and temporal variation of the disease pattern; for this purpose the M protein gene (emm) gene typing is the most widely used genotyping method, with more than 200 emm types recognized. Molecular epidemiological data have been also used for the development of GAS M protein-based vaccines.

METHODS

The aim of this paper was to provide an updated scenario of the most prevalent GAS emm types responsible for invasive infections in developed countries as Europe and North America (US and Canada), from 1st January 2000 to 31st May 2017. The search, performed in PubMed by the combined use of the terms ("emm") and ("invasive") retrieved 264 articles, of which 38 articles (31 from Europe and 7 from North America) met the inclusion criteria and were selected for this study. Additional five papers cited in the European articles but not retrieved by the search were included.

RESULTS

emm1 represented the dominant type in both Europe and North America, replaced by other emm types in only few occasions. The seven major emm types identified (emm1, emm28, emm89, emm3, emm12, emm4, and emm6) accounted for approximately 50-70% of the total isolates; less common emm types accounted for the remaining 30-50% of the cases. Most of the common emm types are included in either one or both the 26-valent and 30-valent vaccines, though some well-represented emm types found in Europe are not.

CONCLUSION

This study provided a picture of the prevalent emm types among invasive GAS (iGAS) in Europe and North America since the year 2000 onward. Continuous surveillance on the emm-type distribution among iGAS infections is strongly encouraged also to determine the potential coverage of the developing multivalent vaccines.

Invasive disease by Streptococcus pyogenes: patients hospitalized for 6 years

INTRODUCTION AND OBJECTIVE

The last years an increase of severe cases of invasive disease (ID) due to Streptococcus pyogenes or streptococcus b-hemolytic group A (SGA) had been detected. The aim of this study was to analyze the epidemiology and the clinical features of ID due to SGA in a tertiary Pediatric Hospital.

MATERIAL AND METHODS

Retrospective study in a Pediatric hospital, of all in-patients with final diagnosis of ID due to SGA during 6 years (2009-2014). To consider ID, SGA had to be isolated in sterile samples; in patients with fascitis necroticans in skin samples or in any sample in patients with the diagnostic of Streptococcal Toxic Shock Syndrome (STSS). The SSTS was defined as hypotension and at least 2 of these criteria: renal failure, hepatic failure, acute respiratory distress, tissue necrosis or desquamative erythematous rash. Demographic data, type of infection, risk factors, clinical presentation, analytical data at admission, treatment, need for admission to a pediatric intensive care unit, microbiological data, hospital stay and evolution were collected.

RESULTS

Fifty-two (52) cases were included (12/10,000 of all inpatients); 3 years-old was the medium age (p25-75: 1.4-6.9 years); 28 (53.8%) were boys. Fourteen patients (26.9%) had risk factors. Fever was the major symptom (51 patients, 98.1%). The skin lesions were the most frequent clinical manifestations found (21; 40.4%). In 50 (96%) cases, SGA was isolated in at least one sterile sample. Skin and soft tissue infections were diagnosed in 14 patients (26.9%), 14 (26.9%) pneumonias, 12 (23.1%) bones and joints infections, 10 (19.2%) SSTS, 6 (11.5%) occult bacteremia, 4 (7.7%) meningitis and 2 (3.8%) sepsis. Surgery was required in 18 cases (34.6%) and 17 patients (32.7%) needed intensive care. The medium hospital stay was 9.5 days (p25-75: 8-15 days). Three patients presented sequels and one patient died.

CONCLUSION

The ID due to SGA was a rare but serious reason for hospital admission. Skin and soft tissue infections, and pleuroneumonia were the most common forms of ID. The mortality of our sample was low despite the serious clinical manifestations.

[Streptococcus pyogenes infection in paediatrics: from pharyngotonsillitis to invasive infections]

BACKGROUND

Streptococcus pyogenes or Group A Streptococci (GAS) cause many infections in infancy. Changes in its epidemiology have been described in recent years, including an increase in invasive infections (iGAS).

METHODS

A retrospective-descriptive study was conducted on children less than 15 years old, with GAS infections, in particular iGAS, and their complications from February 2004-April 2014.

RESULTS

A total of 2,192 positive cultures were obtained of which 92.7% were pharyngeal cultures. Twenty-nine patients were admitted to hospital: 4 with suppurative complications, 7 post-infective, 14 iGAS, and 4 probable iGAS cases. There were no differences in the frequency of GAS isolations/year. Non-invasive isolates were more frequent in winter and spring (P<.001), and 68.3% were in patients younger than 5 years. The incidence of iGAS was 2.1/100,000 children/year. There was no seasonality, and it was more frequent in younger children (P=.039). The most common diagnosis was pneumonia (6/14). Eight patients required intensive care. They were treated empirically with second or third-generation cephalosporin or with intravenous penicillin, and pneumonia required longer treatment times (P=.016). All GAS isolates were sensitive to penicillin, and 10.6% were resistant to erythromycin. The time spent in hospital was longer for iGAS than other cases (P=.028). No patients died.

CONCLUSIONS

Pharyngotonsillitis caused by GAS is common in childhood, and its incidence is increasing in children younger than 5 years. At the moment, post-infectious complications are rare. Invasive infections are the most severe forms of presentation, and are more common in younger children.

A case of descending mediastinitis caused by Streptococcus pyogenes harboring genotype emm25 and sequence type 660

Descending mediastinitis caused by Streptococcus pyogenes (group A streptococcus, GAS) is rare among cases of invasive GAS infection. In this report, we describe a case of a cervical abscess and secondary descending mediastinitis in a previously healthy 39-year-old Japanese man. The patient presented with a 2-week history of a sore throat, and subsequently developed an abscess and descending mediastinitis. We treated the cervical abscess using ampicillin/sulbactam and drainage, and GAS was subsequently isolated in two blood cultures from the patient's admission. Microbiological analyses revealed that the isolate harbored genotype emm25 and sequence type (ST) 660. This strain was susceptible to erythromycin (minimum inhibitory concentration [MIC]: ≤0.12 μg/mL), resistant to minocycline (MIC: >4 μg/mL), and possessed the tet(M) determinant. Although we have reviewed the literature regarding the clinical and microbiological characteristics of descending mediastinitis cause by GAS, little is known regarding epidemiological and clinical characteristics of emm25/ST660 GAS. Furthermore, to best of our knowledge, this is the first reported case of descending mediastinitis caused by emm25/ST660 GAS. Therefore, physicians should be aware of case with a cervical abscess and secondary descending mediastinitis caused by GAS infection, even if the patient is immunocompetent.

Epidemiology of Invasive Group A Streptococcal Infections in the United States, 2005-2012

BACKGROUND

Invasive group A Streptococcus (GAS) infections are associated with significant morbidity and mortality rates. We report the epidemiology and trends of invasive GAS over 8 years of surveillance.

METHODS

From January 2005 through December 2012, we collected data from the Centers for Disease Control and Prevention's Active Bacterial Core surveillance, a population-based network of 10 geographically diverse US sites (2012 population, 32.8 million). We defined invasive GAS as isolation of GAS from a normally sterile site or from a wound in a patient with necrotizing fasciitis (NF) or streptococcal toxic shock syndrome (STSS). Available isolates were emm typed. We calculated rates and made age- and race-adjusted national projections using census data.

RESULTS

We identified 9557 cases (3.8 cases per 100 000 persons per year) with 1116 deaths (case-fatality rate, 11.7%). The case-fatality rates for septic shock, STSS, and NF were 45%, 38%, and 29%, respectively. The annual incidence was highest among persons aged ≥65 years (9.4/100 000) or <1 year (5.3) and among blacks (4.7/100 000). National rates remained steady over 8 years of surveillance. Factors independently associated with death included increasing age, residence in a nursing home, recent surgery, septic shock, NF, meningitis, isolated bacteremia, pneumonia, emm type 1 or 3, and underlying chronic illness or immunosuppression. An estimated 10 649-13 434 cases of invasive GAS infections occur in the United States annually, resulting in 1136-1607 deaths. In a 30-valent M-protein vaccine, emm types accounted for 91% of isolates.

CONCLUSIONS

The burden of invasive GAS infection in the United States remains substantial. Vaccines under development could have a considerable public health impact.

Epidemiology of invasive group A Streptococcus infections in Sydney, Australia

There is concern of global resurgence of invasive group A Streptococcus (iGAS) infections. We compared the clinical and molecular epidemiology of patients admitted with iGAS over two time periods, 2008 and 2010, in Western Sydney, Australia. The annual incidence was 19 cases per 100,000 admissions in 2008, compared to 33 per 100,000 in 2010. An increasing proportion of patients died (0% versus 13%), had an APACHE II score ≥30 (0% versus 19%), and had no known risk-factors (12% versus 25%). A potential skin source was identified as a trigger in fewer cases in 2010 (36% versus 11%). In total, there were 27 different emm types and 11 different emm clusters. There were some new emm types/clusters in 2010 that were not present in 2008. However, the study was not adequately powered to detect statistically significant differences in the distribution of emm types (p = 0.06) and emm clusters (p = 0.16) between the two years. There were also no clear associations between emm types/clusters and severity and clinical manifestations of iGAS infections. Although the proposed 30-valent M protein vaccine encompasses only 47% of our isolates, it will likely provide coverage for at least 71% of iGAS infections due to cross-opsonisation.

Streptococcus pyogenes Pneumonia in Adults: Clinical Presentation and Molecular Characterization of Isolates 2006-2015

Introduction

In the preantibiotic era Streptococcus pyogenes was a common cause of severe pneumonia but currently, except for postinfluenza complications, it is not considered a common cause of community-acquired pneumonia in adults.

Aim and Material and Methods

This study aimed to identify current clinical episodes of S. pyogenes pneumonia, its relationship with influenza virus circulation and the genotypes of the involved isolates during a decade in a Southern European region (Gipuzkoa, northern Spain). Molecular analysis of isolates included emm, multilocus-sequence typing, and superantigen profile determination.

Results

Forty episodes were detected (annual incidence 1.1 x 100,000 inhabitants, range 0.29–2.29). Thirty-seven episodes were community-acquired, 21 involved an invasive infection and 10 developed STSS. The associated mortality rate was 20%, with half of the patients dying within 24 hours after admission. Influenza coinfection was confirmed in four patients and suspected in another. The 52.5% of episodes occurred outside the influenza seasonal epidemic. The 67.5% of affected persons were elderly individuals and adults with severe comorbidities, although 13 patients had no comorbidities, 2 of them had a fatal outcome. Eleven clones were identified, the most prevalent being emm1/ST28 (43.6%) causing the most severe cases.

Conclusions

S. pyogenes pneumonia had a continuous presence frequently unrelated to influenza infection, being rapidly fatal even in previously healthy individuals.

Epidemiology of Invasive Group A Streptococcal Disease in Alaska, 2001 to 2013

The Arctic Investigations Program (AIP) began surveillance for invasive group A streptococcal (GAS) infections in Alaska in 2000 as part of the invasive bacterial diseases population-based laboratory surveillance program. Between 2001 and 2013, there were 516 cases of GAS infection reported, for an overall annual incidence of 5.8 cases per 100,000 persons with 56 deaths (case fatality rate, 10.7%). Of the 516 confirmed cases of invasive GAS infection, 422 (82%) had isolates available for laboratory analysis. All isolates were susceptible to penicillin, cefotaxime, and levofloxacin. Resistance to tetracycline, erythromycin, and clindamycin was seen in 11% (n = 8), 5.8% (n = 20), and 1.2% (n = 4) of the isolates, respectively. A total of 51 emm types were identified, of which emm1 (11.1%) was the most prevalent, followed by emm82 (8.8%), emm49 (7.8%), emm12 and emm3 (6.6% each), emm89 (6.2%), emm108 (5.5%), emm28 (4.7%), emm92 (4%), and emm41 (3.8%). The five most common emm types accounted for 41% of isolates. The emm types in the proposed 26-valent and 30-valent vaccines accounted for 56% and 78% of all cases, respectively. GAS remains an important cause of invasive bacterial disease in Alaska. Continued surveillance of GAS infections will help improve understanding of the epidemiology of invasive disease, with an impact on disease control, notification of outbreaks, and vaccine development.

Trading Capsule for Increased Cytotoxin Production: Contribution to Virulence of a Newly Emerged Clade of emm89 Streptococcus pyogenes

Strains of emm89 Streptococcus pyogenes have become one of the major causes of invasive infections worldwide in the last 10 years. We recently sequenced the genome of 1,125 emm89 strains and identified three major phylogenetic groups, designated clade 1, clade 2, and the epidemic clade 3. Epidemic clade 3 strains, which now cause the great majority of infections, have two distinct genetic features compared to clade 1 and clade 2 strains. First, all clade 3 organisms have a variant 3 nga promoter region pattern, which is associated with increased production of secreted cytolytic toxins SPN (S. pyogenes NADase) and SLO (streptolysin O). Second, all clade 3 strains lack the hasABC locus mediating hyaluronic acid capsule synthesis, whereas this locus is intact in clade 1 and clade 2 strains. We constructed isogenic mutant strains that produce different levels of SPN and SLO toxins and capsule (none, low, or high). Here we report that emm89 strains with elevated toxin production are significantly more virulent than low-toxin producers. Importantly, we also show that capsule production is dispensable for virulence in strains that already produce high levels of SPN and SLO. Our results provide new understanding about the molecular mechanisms contributing to the rapid emergence and molecular pathogenesis of epidemic clade 3 emm89 S. pyogenes.

S. pyogenes (group A streptococcus [GAS]) causes pharyngitis (“strep throat”), necrotizing fasciitis, and other human infections. Serious infections caused by emm89 S. pyogenes strains have recently increased in frequency in many countries. Based on whole-genome sequence analysis of 1,125 strains recovered from patients on two continents, we discovered that a new emm89 clone, termed clade 3, has two distinct genetic features compared to its predecessors: (i) absence of the genes encoding antiphagocytic hyaluronic acid capsule virulence factor and (ii) increased production of the secreted cytolytic toxins SPN and SLO. emm89 S. pyogenes strains with the clade 3 phenotype (absence of capsule and high expression of SPN and SLO) are highly virulent in mice. These findings provide new understanding of how new virulent clones emerge and cause severe infections worldwide. This newfound knowledge of S. pyogenes virulence can be used to help understand future epidemics and conduct new translational research.

Antimicrobial Susceptibility of Invasive Streptococcus pyogenes Isolates in Germany during 2003-2013

A nationwide laboratory-based surveillance study of invasive S. pyogenes infections was conducted in Germany. Invasive isolates (n = 1,281) were obtained between 2003 and 2013. All isolates were susceptible to penicillin, cefotaxime and vancomycin. Tetracycline showed the highest rate of resistant or intermediate resistant isolates with 9.8%, followed by macrolides (4.0%), trimethoprim/sulfamethoxazole (SXT) (1.9%), levofloxacin (1.3%), chloramphenicol (0.9%) and clindamycin (0.7%). The most prominent trends were the appearance of levofloxacin non-susceptible isolates since 2011, and an increase of SXT non-susceptibility since 2012.

Emergence of a New Highly Successful Acapsular Group A Streptococcus Clade of Genotype emm89 in the United Kingdom

Group A Streptococcus (GAS) genotype emm89 is increasingly recognized as a leading cause of disease worldwide, yet factors that underlie the success of this emm type are unknown. Surveillance identified a sustained nationwide increase in emm89 invasive GAS disease in the United Kingdom, prompting longitudinal investigation of this genotype. Whole-genome sequencing revealed a recent dramatic shift in the emm89 population with the emergence of a new clade that increased to dominance over previous emm89 variants. Temporal analysis indicated that the clade arose in the early 1990s but abruptly increased in prevalence in 2008, coinciding with an increased incidence of emm89 infections. Although standard variable typing regions (emm subtype, tee type, sof type, and multilocus sequence typing [MLST]) remained unchanged, uniquely the emergent clade had undergone six distinct regions of homologous recombination across the genome compared to the rest of the sequenced emm89 population. Two of these regions affected known virulence factors, the hyaluronic acid capsule and the toxins NADase and streptolysin O. Unexpectedly, and in contrast to the rest of the sequenced emm89 population, the emergent clade-associated strains were genetically acapsular, rendering them unable to produce the hyaluronic acid capsule. The emergent clade-associated strains had also acquired an NADase/streptolysin O locus nearly identical to that found in emm12 and modern emm1 strains but different from the rest of the sequenced emm89 population. The emergent clade-associated strains had enhanced expression of NADase and streptolysin O. The genome remodeling in the new clade variant and the resultant altered phenotype appear to have conferred a selective advantage over other emm89 variants and may explain the changes observed in emm89 GAS epidemiology.

Sudden upsurges or epidemic waves are common features of group A streptococcal disease. Although the mechanisms behind such changes are largely unknown, they are often associated with an expansion of a single genotype within the population. Using whole-genome sequencing, we investigated a nationwide increase in invasive disease caused by the genotype emm89 in the United Kingdom. We identified a new clade variant that had recently emerged in the emm89 population after having undergone several core genomic recombination-related changes, two of which affected known virulence factors. An unusual finding of the new variant was the loss of the hyaluronic acid capsule, previously thought to be essential for causing invasive disease. A further genomic adaptation in the NADase/streptolysin O locus resulted in enhanced production of these toxins. Recombination-related genome remodeling is clearly an important mechanism in group A Streptococcus that can give rise to more successful and potentially more pathogenic variants.

Increased prevalence of group A streptococcus isolates in streptococcal toxic shock syndrome cases in Japan from 2010 to 2012

Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock, multi-organ failure, and high mortality. In Japan, appropriate notification measures based on the Infectious Disease Control law are mandatory for cases of STSS caused by β-haemolytic streptococcus. STSS is mainly caused by group A streptococcus (GAS). Although an average of 60-70 cases of GAS-induced STSS are reported annually, 143 cases were recorded in 2011. To determine the reason behind this marked increase, we characterized the emm genotype of 249 GAS isolates from STSS patients in Japan from 2010 to 2012 and performed antimicrobial susceptibility testing. The predominant genotype was found to be emm1, followed by emm89, emm12, emm28, emm3, and emm90. These six genotypes constituted more than 90% of the STSS isolates. The number of emm1, emm89, emm12, and emm28 isolates increased concomitantly with the increase in the total number of STSS cases. In particular, the number of mefA-positive emm1 isolates has escalated since 2011. Thus, the increase in the incidence of STSS can be attributed to an increase in the number of cases associated with specific genotypes.

Changes in the clinical and epidemiological features of group A streptococcal bacteraemia in Australia's Northern Territory

OBJECTIVE

Invasive group A streptococcus (iGAS) disease is an important cause of mortality globally. The incidence of iGAS in Australia's tropical Northern Territory (NT) has been previously reported as 32.2/100 000 in Indigenous people for the period 1991-1996. We aimed to measure the incidence and severity of iGAS disease in the NT since this time.

METHODS

We collected demographic data for all GAS blood culture isolates over a 12-year period (1998-2009) from the three hospital laboratories serving the tropical NT. We then collected detailed clinical information from hospital records and databases for the subset of these patients who were admitted to Royal Darwin Hospital during 2005-2009.

RESULTS

There were 295 confirmed cases of GAS bacteraemia over the study period, with a mean (SD) age of 42.1 (22.0) years, and 163 (55.0%) were male. The annual age-adjusted incidence was 15.2 (95% CI 13.4-16.9)/100 000 overall and 59.4 (95% CI 51.2-67.6) in Indigenous Australians. For 2005-2009, there were 123 cases with the most common focus of infection being skin/soft tissue [44 (35.6%)]; 29 patients (23.6%) required intensive care unit admission and 20 (16.3%) had streptococcal toxic shock syndrome. Antecedent sore throat or use of non-steroidal anti-inflammatory drugs was rare, but current or recent scabies, pyoderma and trauma were common.

CONCLUSION

The incidence and severity of iGAS are high and increasing in tropical northern Australia, and urgent attention is needed to improve surveillance and the social determinants of health in this population. This study adds to emerging data suggesting increasing importance of iGAS in low- and middle-income settings globally.

Pediatric invasive streptococcal infection in northern and eastern regions of Hokkaido, Japan from 2010 to 2012

BACKGROUND

The frequency of occurrence of pediatric invasive streptococcal infection in Japan has not been studied, therefore the aim of this study was to survey the northern and eastern regions of Hokkaido from 2010 to 2012.

METHOD

Survey sheets were sent to the pediatric departments at 17 facilities where children in the subject region can be hospitalized. Responses were obtained from all of the 17 facilities.

RESULTS

Seven patients developed group A streptococcal infection over the 3 years, and their ages ranged from 1 day after the birth to 15 years old. Sepsis was diagnosed in five children, and empyema and arthritis in the knee were found in one child each, respectively. The number of cases in children under 15 years old was six excluding the child who was 15 years old, and the incidence rate per 100,000 population was 1.00. Eight children developed group B streptococcal infection, and their ages ranged from 0 days to 2 months after birth. Two cases were the early onset type (age within 7 days) and six cases were the late onset type. Five children developed sepsis and three children developed meningitis. The frequency of occurrence was 0.24 per 1000 births; which was 0.06 per 1000 births for the early onset type and was 0.18 per 1000 births for the late onset type. No reports for group C or group G hemolytic streptococcal infection were obtained.

CONCLUSIONS

The incidence rates identified in the present survey are similar to those in other advanced countries, and appear to be valid.

Characteristics of group A Streptococcus strains circulating during scarlet fever epidemic, Beijing, China, 2011

Scarlet fever is one of a variety of diseases caused by group A Streptococcus (GAS). During 2011, a scarlet fever epidemic characterized by peak monthly incidence rates 2.9–6.7 times higher than those in 2006–2010 occurred in Beijing, China. During the epidemic, hospital-based enhanced surveillance for scarlet fever and pharyngitis was conducted to determine characteristics of circulating GAS strains. The surveillance identified 3,359 clinical cases of scarlet fever or pharyngitis. GAS was isolated from 647 of the patients; 76.4% of the strains were type emm12, and 17.1% were emm1. Almost all isolates harbored superantigens speC and ssa. All isolates were susceptible to penicillin, and resistance rates were 96.1% to erythromycin, 93.7% to tetracycline, and 79.4% to clindamycin. Because emm12 type GAS is not the predominant type in other countries, wider surveillance for the possible spread of emm12 type GAS from China to other countries is warranted.

Arrangement and number of clustered regularly interspaced short palindromic repeat spacers are associated with erythromycin susceptibility in emm12, emm75 and emm92 of group A streptococcus

Clustered regularly interspaced short palindromic repeats (CRISPR) are composed of numerous repeat-spacer units and are considered a prokaryotic defence system against foreign nucleic acids. Since antibiotic-resistant genes are frequently encoded in foreign nucleic acids, the aim of this study was to test whether erythromycin susceptibility in group A streptococcus (Streptococcus pyogenes) is associated with characteristics of CRISPR elements. Erythromycin susceptibility of 330 isolates collected between 1997 and 2003 was analysed. Among 29 emm types, emm12, emm75 and emm92 showed significant changes in erythromycin-resistance rates. By sequencing the spacers from two CRISPR loci, spacer contents in emm12, emm75 and emm92 strains were associated with erythromycin susceptibility. Strains with fewer spacers were more resistant to erythromycin. Moreover, in emm4 strains, which showed no significant change in their annual erythromycin-resistance rate, CRISPR type and number of spacers were not correlated with erythromycin susceptibility. These results highlight a novel association between CRISPR spacer content and erythromycin susceptibility in group A streptococcus.

Changes in Streptococcus pyogenes causing invasive disease in Portugal: evidence for superantigen gene loss and acquisition

The emergence of highly virulent and successful Streptococcus pyogenes (group A streptococci - GAS) clones has been attributed to the exchange of virulence factors by lateral gene transfer mechanisms, which strongly contribute to genomic diversity. We characterized a collection of 191 GAS isolates recovered from normally sterile sites in Portugal during 2006-2009 and compared them to invasive isolates obtained during 2000-2005. Antimicrobial resistance rates did not change significantly between the two periods and were generally low. In 2006-2009, emm1, emm89, emm3, and emm6 represented 60% of the isolates. The chromosomally encoded superantigen (SAg) genes speG and smeZ were present in the majority (>90%) of the isolates, while speJ was found in only 45%. The phage encoded SAgs varied greatly in prevalence (2-53%). The distribution of emm types, pulsed-field gel electrophoresis profiling (PFGE) clusters, and SAg profiles changed significantly between the periods, although there were no statistically supported changes in the prevalence of individual types. While the macrolide susceptible clone emm1-T1-ST28 remained dominant (28%), there was a significant decrease in clonal diversity as indicated by both PFGE profiling and emm typing. This was accompanied by intra-clonal divergence of SAg profiles, which was statistically confirmed for isolates representing emm1, emm28, and emm44. This diversification was associated with the loss and acquisition of SAg genes, carried by phages and of chromosomal origin. These data suggest an ongoing genomic diversification of GAS invasive isolates in Portugal that may contribute to the persistence of clones with improved fitness or virulence.

Serious group a streptococcal infections

The spectrum of illnesses caused by group A streptococcus (GAS) includes invasive infections, noninvasive infections, and noninfectious complications. Increasingly virulent infections associated with high morbidity and mortality have been observed since the late 1980s and continue to be prevalent in North America and worldwide. Penicillin remains the therapy of choice, with the addition of clindamycin recommended in high risk cases. Early recognition of GAS as the cause of these serious clinical syndromes is critical for timely administration of appropriate therapy. In this review, the pathophysiology, clinical manifestations, and treatment of invasive GAS infections are discussed.

Susceptibility and emm type of Streptococcus pyogenes isolated from children with severe infection

Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of various antimicrobial agents were measured against 12 strains of Streptococcus pyogenes isolated from children with invasive infections between 2003 and 2012. The patients ranged in age from 1 day to 15 years, with patients younger than 5 years, including three neonates, accounting for a half of the patients. The disease was sepsis in four patients, skin and soft tissue infection in three patients, retropharyngeal abscess in two patients, pneumonia plus sepsis in one patient, empyema in one patient, and pyogenic arthritis in one patient. One patient with sepsis died, while cure without sequelae was achieved in all the remaining patients. When classified by type, emm1 (six strains) was the most prevalent type, followed by emm12 (two strains). The MIC₉₀/MBC₉₀ values were 0.015/0.015 μg/mL for penicillin G, 0.03/0.03 μg/mL for ampicillin, 0.015/0.03 μg/mL for cefotaxime, 0.03/0.03 μg/mL for ceftriaxone, 0.008/0.008 μg/mL for panipenem, 0.008/0.008 μg/mL for meropenem, and ≤0.004/≤0.004 μg/mL for doripenem, indicating the superior antimicrobial activities of carbapenem.

Group A streptococci clones associated with invasive infections and pharyngitis in Portugal present differences in emm types, superantigen gene content and antimicrobial resistance

Background

A few lineages of Group A streptococci (GAS) have been associated with a reemergence of severe invasive streptococcal disease in developed countries. However, the majority of the comparisons between invasive and non-invasive GAS isolates have been performed for collections of reduced genetic diversity or relied on limited typing information to distinguish clones. We characterized by several typing methods and compared a collection of 160 isolates recovered from normally sterile sites with 320 isolates associated with pharyngitis and recovered in the same time period in Portugal.

Results

Although most of the isolates belonged to clones that were equally prevalent in invasive infections and pharyngitis, we identified markers of invasiveness, namely the emm types 1 and 64, and the presence of the speA and speJ genes. In contrast, emm4, emm75, and the ssa and speL/M genes were significantly associated with pharyngitis. There was a strong agreement between the emm type, the superantigen (SAg) genes and the clusters defined by pulsed-field gel electrophoresis (PFGE) profiling. Therefore, combinations of particular emm types and SAg genes frequently co-occurred in the same PFGE cluster, but there was no synergistic or antagonistic interaction between them in determining invasiveness. Only macrolide-susceptible PFGE clones were significantly associated with invasive infections or pharyngitis, while the clones of resistant isolates sharing all other molecular properties analyzed were equally prevalent in the two groups of isolates.

Conclusions

This study confirmed the importance of the widely disseminated emm1-T1-ST28 clone in invasive infections but also identified other clones linked to either invasive infections (emm64-ST164) or pharyngitis (emm4-T4-ST39), which may be more limited in their temporal and geographical spread. Clonal properties like some emm types or SAg genes were associated with disease presentation, highlighting the importance of bacterial genetic factors to the outcome of GAS infections, although other, yet unidentified factors may also play an important role.

Current insights in invasive group A streptococcal infections in pediatrics

A rising incidence of invasive group A Streptococcus infections (IGASI) has been noted in children in the past three decades. The relative frequency of the infection types showed marked differences to IGASI in adults, and severity of the disease resulted in a mortality rate usually comprising between 3.6% and 8.3%. The emm1-type group A Streptococcus (GAS) subclone displaying a particular pattern of virulence factors was widely disseminated and prevalent in children with IGASI while the emm3-type GAS subclone appeared as a recent emerging genotype. However, the implication of these hypervirulent clones in the increase of IGASI in children is still controversial. Recent advances in our knowledge on pathogenesis of IGASI underlined that deregulation of virulence factor production, individual susceptibility, as well as exuberant cytokine response are important factors that may account for the severity of the disease in children. Future changes in IGASI epidemiology are awaited from current prospects for a safe and effective vaccine against GAS. IGASI are complex infections associating septic, toxic, and immunological disorders. Treatment has to be effective on both the etiologic agent and its toxins, due to the severity of the disease associated to the spread of highly virulent bacterial clones. More generally, emergence of virulent clones responsible for septic and toxic disease is a matter of concern in pediatric infectiology in the absence of vaccination strategy.