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Screening for Staphylococcus epidermidis markers discriminating between skin-flora strains and those responsible for
J O Galdbart1, J Allignet, H S Tung
1Unité des Staphylocoques, Centre National de Référence des Staphylocoques, Institut Pasteur, Paris, and Service de Microbiologie, Hôpital Beaujon, A.P.-H.P., Clichy, France.
Abstract:
Fifty-four Staphylococcus epidermidis strains responsible for infections of joint prostheses and 23 strains isolated from skin flora were studied for markers of virulence, to discriminate invasive strains from normal flora. They were screened for binding to polystyrene and matrix proteins and for the presence of staphylococcal genes involved in adhesion. The ica operon involved in biofilm formation was the only marker discriminating between these 2 categories of strains.
Insights
The ica operon, crucial for biofilm formation, distinguishes invasive Staphylococcus epidermidis from normal skin flora. This finding aids in identifying virulent strains causing joint prosthesis infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Biotechnology
Background:
- Staphylococcus epidermidis is a common cause of prosthetic joint infections.
- Distinguishing between commensal and virulent strains is crucial for effective treatment.
- Virulence factors in S. epidermidis are not fully understood.
Purpose of the Study:
- To identify specific virulence markers that differentiate invasive S. epidermidis strains from those found in normal skin flora.
- To investigate the role of adhesion and biofilm formation in S. epidermidis pathogenicity.
Main Methods:
- Studied 54 S. epidermidis strains from joint infections and 23 from skin flora.
- Assessed bacterial binding to polystyrene and extracellular matrix proteins.
- Screened for staphylococcal genes associated with adhesion, including the ica operon.
Main Results:
- The ica operon, essential for biofilm production, was present in strains causing infections.
- Binding to polystyrene and matrix proteins did not consistently differentiate between invasive and commensal strains.
- The ica operon was the sole genetic marker that clearly distinguished invasive strains from normal flora.
Conclusions:
- The ica operon is a key virulence factor for Staphylococcus epidermidis, particularly in prosthetic joint infections.
- Biofilm formation mediated by the ica operon is critical for S. epidermidis to establish invasive infections.
- Targeting the ica operon could be a potential strategy for preventing or treating S. epidermidis implant-associated infections.