What toxin is responsible for systemic toxicity in necrotizing fasciitis caused by Streptococcus pyogenes (Streptococcus pyogenes)?

From the Guidelines

The toxin responsible for systemic toxicity in necrotizing fasciitis caused by Streptococcus pyogenes is Streptococcal Pyrogenic Exotoxins (SpeA, SpeB). This is based on the fact that these exotoxins function as superantigens, triggering massive activation of T-cells and leading to an overwhelming release of inflammatory cytokines, including TNF-alpha, IL-1, and IL-6, which results in the characteristic systemic manifestations of toxic shock syndrome that often accompanies severe invasive Streptococcus pyogenes infections 1.

Key Points

• Streptococcal Pyrogenic Exotoxins (SpeA, SpeB) are the primary mediators of systemic toxicity in necrotizing fasciitis caused by Streptococcus pyogenes.
• These exotoxins stimulate a massive activation of T-cells, leading to an overwhelming release of inflammatory cytokines.
• The cytokine storm results in the characteristic systemic manifestations of toxic shock syndrome, including shock, multi-organ failure, and disseminated intravascular coagulation.
• Other exotoxins produced by S. pyogenes can also contribute to systemic toxicity, but SpeA and SpeB are considered the primary mediators.

Treatment

The treatment of necrotizing fasciitis caused by Streptococcus pyogenes involves prompt surgical consultation and empiric antibiotic treatment, which should be broad and include agents effective against both aerobes and anaerobes 1.

• Penicillin plus clindamycin is recommended for treatment of documented group A streptococcal necrotizing fasciitis.
• Clindamycin suppresses streptococcal toxin and cytokine production, and has been found to be superior to penicillin in animal models.
• Intravenous immunoglobulin (IVIG) therapy may be considered in patients with necrotizing infections caused by GAS, but its efficacy and safety are still being studied 1.

From the Research

Toxin Responsible for Systemic Toxicity in Necrotizing Fasciitis

The toxin responsible for systemic toxicity in necrotizing fasciitis caused by Streptococcus pyogenes is:

• Streptococcal pyrogenic exotoxins (SpeA, SpeB) 2, 3

Evidence from Studies

Studies have shown that Streptococcus pyogenes can cause a variety of diseases, including necrotizing fasciitis, which is often associated with streptococcal toxic shock syndrome 4, 5, 6. The toxin responsible for this systemic toxicity is believed to be streptococcal pyrogenic exotoxins (SpeA, SpeB), which act as superantigens and cause tissue injury and necrosis 2. A study using a mouse model of necrotizing fasciitis found that the expression of these toxins was drastically upregulated during infection 3.

Characteristics of the Toxin

The streptococcal pyrogenic exotoxins (SpeA, SpeB) are:

• Superantigens that cause tissue injury and necrosis 2
• Drastically upregulated during infection in a mouse model of necrotizing fasciitis 3
• Involved in the pathogenesis of streptococcal toxic shock syndrome 4, 5, 6