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Published on: October 1, 2012

The production of pyrogenic exotoxins by group A streptococci

G Hallas

    The Journal of Hygiene
    |August 1, 1985
    PubMed

    Insights

    Recent scarlet fever outbreaks are linked to specific M types of Group A Streptococcus. These strains predominantly produce streptococcal pyrogenic exotoxins (SPE) B and C, but not SPE A, unlike older strains.

    Area of Science:

    • Microbiology
    • Infectious Diseases
    • Molecular Epidemiology

    Background:

    • Group A Streptococcus (GAS) causes scarlet fever, a significant public health concern.
    • Scarlet fever outbreaks have been associated with specific M types of GAS.
    • Streptococcal pyrogenic exotoxins (SPEs) are virulence factors implicated in scarlet fever pathogenesis.

    Purpose of the Study:

    • To investigate the M types and SPE profiles of GAS strains from recent scarlet fever outbreaks.
    • To compare the SPE production of recent GAS isolates with historical strains.
    • To determine the prevalence of SPE types A, B, and C in contemporary scarlet fever-causing GAS.

    Main Methods:

    • Isolation and M typing of GAS from recent scarlet fever cases and sporadic infections.
    • Detection of SPE types A, B, and C using isoelectric focusing and immunoprecipitation.
    • Analysis of historical GAS strains isolated before 1940 for comparison.

    Main Results:

    • Recent scarlet fever outbreaks involved GAS M types 1, 3, 4, 6, 12, 18, 22, and 66.
    • SPE B was detected in 70% and SPE C in 40% of recent strains; SPE A was absent.
    • Historical strains (pre-1940) showed the presence of SPE A, unlike recent isolates.

    Conclusions:

    • Contemporary scarlet fever epidemics are driven by specific GAS M types lacking SPE A but producing SPE B and C.
    • The shift in SPE profiles suggests potential evolutionary changes in GAS virulence factors.
    • Understanding these epidemiological and molecular characteristics is crucial for controlling scarlet fever.

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