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Superantigen profiling of Staphylococcus aureus infective endocarditis isolates.
Jin-Won Chung1, Melissa J Karau2, Kerryl E Greenwood-Quaintance2
1Divisions of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, MN, USA; Division of Infectious Diseases, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
Diagnostic Microbiology and Infectious Disease
|April 22, 2014
Summary
Over half of Staphylococcus aureus isolates causing endocarditis produce superantigens, which are functional. Methicillin-resistant strains showed a higher prevalence of specific superantigen genes.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Superantigen production by Staphylococcus aureus in endocarditis is not well-defined.
- Staphylococcus aureus is a significant cause of infective endocarditis.
Purpose of the Study:
- To determine the frequency and types of superantigen genes in S. aureus isolates from endocarditis patients.
- To assess the functionality of detected superantigens and their association with clinical outcomes.
Main Methods:
- Testing 154 S. aureus isolates from endocarditis cases using PCR and ELISA for staphylococcal enterotoxins A-E, H, and TSST-1.
- Utilizing an HLA-DR3 transgenic mouse splenocyte proliferation assay to evaluate superantigen activity.
Main Results:
- 50.8% of isolates carried at least one superantigen gene; 16.9% carried more than two.
- tst gene (28.6%) was most common, followed by seb (27%), sea (22.2%), sed (20.6%), see (17.5%), and sec (11.1%).
- Methicillin-resistant S. aureus showed higher sed detection (P < 0.05); superantigen genes were not linked to mortality (P = 0.81).
- 75% of PCR-positive isolates induced splenocyte proliferation, indicating functional superantigens.
Conclusions:
- More than half of S. aureus isolates causing endocarditis possess functional superantigen genes.
- Specific superantigen gene profiles may differ between methicillin-resistant and methicillin-susceptible S. aureus endocarditis isolates.
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