[Characteristics of group A streptococcal meningitis in children]. / Caractéristiques des méningites à streptocoque du groupe A de l'enfant.

Group A streptococcal (GAS) meningitis in children are rare. The aim of this study was to analyze the clinical, biological and outcome data on GAS meningitis recorded in the Bacterial Meningitis (BM) French Surveillance Network (GPIP/ACTIV). From 2001 through 2012, 4,564 children suffering from proven bacterial meningitis were recorded in the data base. Among them, 0.7 % were GAS infections. The median age was 5.6 years. A history of community acquired infection before the onset of GAS meningitis was frequent. Apart from the identification of the bacterial species, GAS meningitis were clinically and biologically indistinguishable from meningitis caused by other pathogens notably S. pneumoniae. Case fatality rate was 8 %.

[Streptococcus pyogenes pathogenic factors]. / Facteurs de pathogénicité de Streptococcus pyogenes.

The pathogenicity of ß-hemolytic group A streptococcus (GAS) is particularly diverse, ranging from mild infections, such as pharyngitis or impetigo, to potentially debilitating poststreptococcal diseases, and up to severe invasive infections such as necrotizing fasciitis or the dreaded streptococcal toxic shock syndrome. This variety of clinical expressions, often radically different in individuals infected with the same strain, results from a complex interaction between the bacterial virulence factors, the mode of infection and the immune system of the host. Advances in comparative genomics have led to a better understanding of how, following this confrontation, GAS adapts to the immune system's pressure, either peacefully by reducing the expression of certain virulence factors to achieve an asymptomatic carriage, or on the contrary, by overexpressing them disproportionately, resulting in the most severe forms of invasive infection.

[Rapid antigen detection tests for group A streptococcus in children with pharyngitis]. / Tests de diagnostic rapide dans les angines de l'enfant.

Group A streptococcus (GAS) is the most frequently identified bacterium in children with acute pharyngitis. Clinical signs and symptoms cannot distinguish accurately between viral and GAS pharyngitis. Rapid antigen detection tests (RADTs) can identify GAS by an immunologic reaction within a few minutes. Compared to throat culture, most RADTs have a high specificity (around 95 %), allowing antibiotic prescribing on the basis of a positive RADT result. Similarly, the negative predictive value of RADTs seems sufficiently high (around 95 %) to ensure against the presence of GAS in case of a negative RADT result. Among several factors affecting RADT sensitivity, the training and expertise of the person performing the test and the quality of the throat swab specimen seem to be key determinants. Available evidence suggests that clinical prediction rules for the triage of children who should undergo GAS testing are not sufficiently accurate. Implementing RADTs into clinical practice has an important impact on antibiotic prescription rates, for a reduction of about 30 %. French guidelines that recommend using RADTs in all children above 3 years of age presenting with pharyngitis without backup culture of negative tests seem relevant in this context.

[Epidemiology of invasive group A streptococcal infections in developed countries : the Canadian experience with necrotizing fasciitis]. / Épidémiologie des infections invasives à streptocoques du groupe A dans les pays industrialisés : l'exemple des fasciites nécrosantes au Canada.

In industrialized countries, group A streptococcal infections were a source of concern, mainly due to the occurrence of rheumatic fever and its cardiac complications. At present, the incidence of rheumatic fever is decreasing in these countries, giving way to an increasing occurrence of invasive streptococcal group A infections with high level of morbidity and mortality. Streptococcal necrotizing fasciitis, a specific entity, emerged these last decades, often in association with chickenpox. The introduction of the varicella vaccine in the province of Quebec routine immunization program, was followed by a significant decrease in the number of necrotizing fasciitis or other skin and soft-tissues infections in our pediatric population. However, in our experience at the CHU Sainte-Justine, this immunization program has not been helpful to reduce the overall incidence of invasive group A streptococcal infections. Conversely, an increase in the number of pleuro-pulmonary and osteo-articular infections was observed.

[Use of group A streptococcal rapid diagnostic test in extra-pharyngeal infections]. / Utilisation des tests de diagnostic rapide du streptocoque du groupe A en dehors de l'angine.

The purpose of this study was to assess the performances of the group A streptococcus (GAS) rapid antigen diagnostic tests (RADTs) in extra-pharyngeal infections. Between October 2009 and June 2014, 368 patients (median age: 48 months) were enrolled. The pathologies involved were : 160 perineal infections (44 %), 69 blistering distal dactylitis (19 %), 55 cervical lymphadenitis (15 %), 31 crusty or bleeding rhinitis (8 %), and 53 other diseases (14 %). The sensitivity of GAS-RADT used was 96 % (95 % CI: 92-99 %), the specificity 81 % (95 % CI: 75- 86 %), the negative predictive value 97 % (CI 95 %: 93-99 %), and the positive predictive value 79 % (95 % CI: 73-85 %). Finally, positive and negative likelihood ratio were 5 (95 % CI: 4-7) and 0.05 (95 % CI: 0.02-0.11) respectively. The GAS-RADTs developed for pharyngitis have comparable performances in these settings and therefore can be used.

[Management of severe invasive group A streptococcal infections]. / Prise en charge des infections invasives et graves à streptocoque du groupe A.

The group A streptococcus (GAS) is the 5(th) responsible pathogen of invasive infections in children in France. These particularly severe diseases are dominated in children by soft tissue infection, isolated bacteremia but also osteoarthritis. Other complications are rare in France such as lung infections, necrotizing fasciitis (NF) and streptococcal toxic shock syndrome (STSS). More unusual localizations such as meningitis, neonatal infections, severe ear and throat and gastrointestinal infections and vascular disorders are also described. Based on published series, mortality ranging from 0-8 % of cases, is high but still lower than that observed in adults. Probabilistic antibiotherapy includes a ß-lactam with anti-SGA but also anti-staphylococcal (predominantly methi-S in France) activity such as clavulanic acid- amoxicillin followed by amoxicillin as soon as identification of SGA is performed. The addition of an anti-toxin antibiotic such as clindamycin is recommended particularly in NF or STSS or clinical signs suggestive of toxin production by the SGA (rash, gastrointestinal signs, hemodynamic disorders). The use of intravenous polyvalent immunoglobulins must also be discussed in NF and STSS. In all cases surgery should be discussed. The prognosis of these potentially very severe infections is related to their early diagnosis and treatment. A better understanding of the pathophysiology of these infections may optimize their management but also their prevention.

[Diagnostic of group A streptococcal blistering distal dactylitis]. / Diagnostic des tournioles à streptocoque du groupe A.

Blistering distal dactylitis is a distinct clinical entity, generally due to S. pyogenes, unfrequently reported. Characteristically, blistering distal dactylitis is described as a localized infection involving the distal phalanx of the digits, and it usually presents as a fluid-filled blister. Between October 2009 and June 2014, 69 children (median age: 60 months, extremes: 0,6-176) were enrolled. The sensitivity of GAS rapid antigen detection test was 97 % (CI 95 %: 83-100 %), the specificity was 76 % (CI 95 %: 60-89 %), the negative predictive value was 97 % (CI 95 %: 83-100 %), and the positive predictive value 76 % (CI 95 %: 60-89 %). All patients with a positive GAS rapid antigen test were treated with antibiotics (amoxicillin essentially) and cured without surgery.

[Group A streptococcal perineal infection in children]. / Infections périnéales à streptocoque du groupe A chez l'enfant.

Perineal diseases in children are usually caused by group A streptococcus (GAS). If the natural course of untreated cases is not known, it is well known that symptoms do not resolve spontaneously and can persist often for many months, until appropriate diagnosis and effective treatment are instituted. Furthermore, failures and recurrences after penicillin treatment are frequent. From 2009 to 2014, 165 perineal infections (median age: 48 months, extremes: 0.4-139) were enrolled by 15 pediatricians: 4 balanitis, 29 vulvo-vaginal diseases and 132 perianal infections. Painful defecation, anal fissures and macroscopic blood in stools were significantly more frequent in GAS perianal infections than negative GAS infections (p<0.01). The performance of GAS-rapid antigen test compared to the GAS culture was : sensitivity 97 % [CI 95 %: 89-100 %], specificity 76 % [CI 95 %: 66-84 %], negative predictive value 97 % [CI 95 %: 91-100 %], positive predictive value 71 % [CI 95 %: 60-80 %].