title: New understandings in Streptococcus pyogenes.
abstract: OBJECTIVE
  A resurgence of invasive group A streptococcal infections highlights the need for better knowledge of streptococcal biology. This review summarizes the recent advances in our understanding of the field.
  
  
  RESULTS
  Invasive group A streptococcal infections cause significant morbidity and mortality worldwide. The current upsurge of invasive infections in developed countries is predominantly linked to the spread of a clonal hypervirulent population of M1T1 serotype strains (emm1), although sporadic increases in other types have been reported, including emm3 strains in the UK, and emm28 strains among cases of puerperal sepsis. Mutations of a regulatory system, CovR/S (control of virulence), are important in the transition of emm1 strains from noninvasive to invasive phenotype. New research has been undertaken to identify major virulence factors that typify the invasive phenotype. In less-developed regions, the importance of rheumatic carditis and need for a vaccine that addresses a much wider range of streptococcal emm types predominates research efforts.
  
  
  CONCLUSIONS
  Advances in molecular technology have furthered our understanding of virulence factors that underpin group A streptococcus invasiveness. The increased prevalence of invasive disease coupled with the devastating effects of chronic rheumatic heart disease, affecting predominantly low-income regions, underline the need for the development of an effective vaccine.
authors.affiliation: Department of Infectious Diseases and Immunity, Imperial College London, Hammersmith Hospital, London, UK.
authors.forename: Nicola N
authors.initials: NN
authors.lastname: Lynskey
authors.forename: Richard A
authors.initials: RA
authors.lastname: Lawrenson
authors.forename: Shiranee
authors.initials: S
authors.lastname: Sriskandan
mesh_terms: D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D012214:Rheumatic Heart Disease / Q000453:epidemiology / Q000382:microbiology; D013290:Streptococcal Infections / Q000150:complications / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000276:immunology / Q000302:isolation & purification* / Q000472:pathogenicity*; D006113:United Kingdom; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D037521:Virulence Factors