Pathogenesis of Group A Streptococcal Infections

Abstract

SUMMARY Group A streptococci are model extracellular gram-positive pathogens responsible for pharyngitis, impetigo, rheumatic fever, and acute glomerulonephritis. A resurgence of invasive streptococcal diseases and rheumatic fever has appeared in outbreaks over the past 10 years, with a predominant M1 serotype as well as others identified with the outbreaks. emm (M protein) gene sequencing has changed serotyping, and new virulence genes and new virulence regulatory networks have been defined. The emm gene superfamily has expanded to include antiphagocytic molecules and immunoglobulin-binding proteins with common structural features. At least nine superantigens have been characterized, all of which may contribute to toxic streptococcal syndrome. An emerging theme is the dichotomy between skin and throat strains in their epidemiology and genetic makeup. Eleven adhesins have been reported, and surface plasmin-binding proteins have been defined. The strong resistance of the group A streptococcus to phagocytosis is related to factor H and fibrinogen binding by M protein and to disarming complement component C5a by the C5a peptidase. Molecular mimicry appears to play a role in autoimmune mechanisms involved in rheumatic fever, while nephritis strain-associated proteins may lead to immune-mediated acute glomerulonephritis. Vaccine strategies have focused on recombinant M protein and C5a peptidase vaccines, and mucosal vaccine delivery systems are under investigation.

Understanding rheumatic fever

“…Several streptococcal and human protein cross-reactive antibodies found in the sera of RF patients and immunized rabbits and mice have been described [29]. Antibodies against streptococci' wall GlcNAc display cross-reactivity against laminin, a protein present in extracellular matrix that surrounds heart cells and in the valves.…”

The Issue of Species Specificity of Bacterial Infection, How to Address it Experimentally

“…GAS is able to induce severe life -threatening invasive infections such as necrotizing fasciitis, streptococcal toxic shock and myositis. Colonization of the oropharynx is also associated with rheumatic fever, an autoimmune disorder which is the leading cause of preventable childhood heart disease in the developing world [56] . Because of the strict restriction of GAS to humans, in vivo models of infection in mice are not pertinent to the study of this pathogen.…”

Kinderdermatologie

“…Bei streptogener Impetigo sollte auch bei fehlenden klinischen Symptomen (Ödem, Bluthochdruck, Hämaturie) nach 3-6 Wochen eine Urinanalyse erfolgen, da einzelne Stämme von β-hämolysierenden Streptokokken der Gruppe A eine sekundäre Nierenschädigung im Sinne einer Post-Streptokokken-Glomerulonephritis auslösen können [10].…”

“…4 Disseminierte und Spätinfektion mit neurologischer SymptomatikDer Preis in Höhe von10.000 Euro wird in diesem Jahr anlässlich der 45. Tagung der Deutschen Dermatologischen Gesellschaft Ende April 2009 in Dresden für wissenschaftliche Arbeiten in der klinischen und experimentellen Hautkrebsforschung aus dem deutschsprachigen Raum verliehen.…”