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Exploring the pathogenesis of necrotizing fasciitis due to Streptococcus pneumoniae
Eun J Kwak1, Jo-Ann McClure, Allison McGeer
1Department of Medicine, University of Ottawa, Ontario, Canada.
Abstract:
Monobacterial necrotizing fasciitis is a rare form of soft tissue infection usually caused by the group A beta-hemolytic Streptococcus. Soft tissue infection is an uncommon clinical manifestation of invasive disease due to Streptococcus pneumoniae. We describe 3 cases of pneumococcal necrotizing fasciitis and explore potential pathogen-specific mechanisms of pathogenesis. The clinical characteristics of necrotizing fasciitis due to S. pneumoniae and group A beta-hemolytic Streptococcus appear to overlap. The similarities include predominant occurrence in elderly adults with underlying chronic illness, predilection for lower extremity infection, progression to toxic shock-like syndrome and a high case fatality rate. No DNA fragments corresponding to speA, speB or speC were amplified by PCR from the 3 pneumococcal isolates. Western immunoblot revealed no evidence of SpeA, SpeB or SpeC protein expression. Evaluation for protease production and cytotoxicity was unrevealing. The similar clinical presentation of pneumococcal necrotizing fasciitis to the disease caused by the group A beta-hemolytic Streptococcus has important therapeutic implications. The molecular mechanisms underlying the pathogenesis are unclear. Prospective population-based studies are required to define the epidemiology of this infection.
Insights
Necrotizing fasciitis, a severe soft tissue infection, can be caused by Streptococcus pneumoniae, not just Group A Streptococcus. This rare pneumococcal form shares clinical traits with streptococcal infections, including high fatality rates.
Area of Science:
- Infectious Diseases
- Microbiology
- Pathogenesis
Background:
- Necrotizing fasciitis is typically a Group A Streptococcus infection.
- Invasive Streptococcus pneumoniae disease rarely presents as soft tissue infection.
Observation:
- Three cases of monobacterial necrotizing fasciitis caused by Streptococcus pneumoniae are presented.
- Clinical features of pneumococcal necrotizing fasciitis overlap with Group A Streptococcus infections.
- Affected patients were elderly with chronic illnesses, often presenting with lower extremity infections and toxic shock-like syndrome.
Findings:
- Pneumococcal isolates lacked genes (speA, speB, speC) and proteins associated with Group A Streptococcus virulence.
- No evidence of protease production or cytotoxicity was found in pneumococcal isolates.
- The molecular mechanisms driving pneumococcal necrotizing fasciitis pathogenesis remain unclear.
Implications:
- The similar clinical presentation necessitates considering Streptococcus pneumoniae in necrotizing fasciitis diagnosis and treatment.
- Further research is needed to elucidate pathogen-specific mechanisms and define the epidemiology of pneumococcal necrotizing fasciitis.