There is concern that group A streptococci, which have caused less serious infections in developed countries in recent decades, may be acquiring greater virulence. We describe 20 patients from the Rocky Mountain region who had group A streptococcal infections from 1986 to 1988 that were remarkable for the severity of local tissue destruction and life-threatening systemic toxicity. Among the 20 patients (median age, 36), necrotizing fasciitis with or without myositis was the most common soft-tissue infection (55 percent). Nineteen patients (95 percent) had shock, 16 (80 percent) had renal impairment, and 11 (55 percent) had acute respiratory distress syndrome. The mortality rate was 30 percent. All patients but 1 had positive tissue cultures for Streptococcus pyogenes; 12 had positive blood cultures. Most of the patients had no underlying disease; 2 used intravenous drugs. Strains of group A beta-hemolytic streptococci isolated from 10 patients were not of a single M or T type; however, 8 of the 10 strains produced pyrogenic exotoxin A (scarlet fever toxin A, a classic erythrogenic toxin), which has rarely been observed in recent years. From our study of this cluster of severe streptococcal infections with a toxic shock-like syndrome, we conclude that in our region, more virulent group A streptococci have reappeared that produce the pyrogenic toxin A associated with scarlet fever.

Severe group a streptococcal infections associated with a toxic shock-life syndrome and scarlet fever toxin

https://www.cell.com/trends/molecular-medicine/pdf/S1471-4914(13)00181-0.pdf

Streptococcal superantigens: categorization and clinical associations.

https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(14)63094-9/pdf

Necrotizing soft tissue infections caused by Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis of groups C and G in western Norway

Purpose of reviewA 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.Recent findingsInvasive group A streptococcal infections cause significant morbid

New understandings in Streptococcus pyogenes.

Streptococcus pyogenes (group A streptococcus, GAS) is responsible for a wide range of pathologies ranging from mild pharyngitis and impetigo to severe invasive soft tissue infections. Despite the continuing susceptibility of the bacterium to β-lactam antibiotics there has been an unexplained resurgence in the prevalence of invasive GAS infection over the past 30 years. Of particular importance was the emergence of a GAS-associated sepsis syndrome that is analogous to the systemic toxicosis associated with TSST-1 producing strains of Staphylococcus aureus. Despite being recognized for over 20 years, the etiology of GAS associated sepsis and the streptococcal toxic shock syndrome remains poorly understood. Here we review the virulence factors that contribute to the etiology of GAS associated sepsis with a particular focus on coagulation system interactions and the role of the superantigens in the development of streptococcal toxic shock syndrome.

https://www.tandfonline.com/doi/pdf/10.4161/viru.26400

The contribution of group A streptococcal virulence determinants to the pathogenesis of sepsis

Background In this study, we examined the role of superantigen genes and emm genotypes of clinical Streptococcus pyogenes isolates collected in Germany between 1997 and 2003. Methods Multiplex polymerase chain reaction for all 11 currently known superantigen genes and sequencing for emm types were used. Results Using a 2-step explorative data analysis procedure, we found that after combined analysis of superantigen genes and emm types, only the superantigen genes spea1-spea3, spem, and spea4 have a predictive value for invasiveness, with odds ratios of 7.992, 3.209, and 2.323, respectively. The predictive value for invasiveness of emm1 was lost after combined analysis because of the association between emm type and the highly predictive superantigen genes. On the other hand, presence of the superantigen gene ssa and of emm77 are predictors of noninvasiveness, with odds ratios of 0.370 and 0.271, respectively. Conclusions These results indicate that the presence of superantigen genes is more important for the invasiveness of group A Streptococcus infection than emm type and may be the connection between the high-risk HLA type of the host and the pathogen. Furthermore, we found a very clear correlation between the presence of the genes spea1-spea3 and the presence of the gene emm1, which indicates that the relationship between emm1 and invasiveness is based on the superantigen gene profile. Our data suggest that the superantigen gene profile is of high importance for the clinical outcome of group A Streptococcus infections.

/pdf/superantigen-genes-are-more-important-than-the-emm-type-for-39fzhy2vey.pdf

Superantigen Genes Are More Important than the emm Type for the Invasiveness of Group A Streptococcus Infection

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Superantigen Genes Are More Important than the emm Type for the Invasiveness of Group A Streptococcus Infection