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Updated: May 1, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Decreased susceptibility of Staphylococcus aureus small-colony variants toward human antimicrobial peptides
Regine Gläser1, Karsten Becker2, Christof von Eiff3
1Department of Dermatology, University of Kiel, Kiel, Germany.
Abstract:
Staphylococcus aureus is a frequent resident of human nose and skin in many individuals, but it is also able to cause a variety of serious infections including those of the skin and soft tissue. There is increasing evidence that particularly persistent, relapsing, and difficult-to-treat infections caused by S. aureus are associated with the formation of the small-colony variant (SCV) phenotype. The aim of this study was to investigate the hypothesis that (i) skin-derived antimicrobial peptides (AMPs) exhibit a reduced activity against SCVs and (ii) that switching into the SCV phenotype may endow S. aureus with a decreased susceptibility toward the killing activity of human stratum corneum. Here, we show that clinically derived S. aureus SCVs are less susceptible to the bactericidal activity of different human skin-derived AMPs as compared with their isogenic corresponding wild-type strains. Similarly, a S. aureus hemB mutant displaying the SCV phenotype was less susceptible to the antimicrobial activity of AMPs than its hemB-complemented mutant. These findings were accompanied by a higher resistance of SCVs to the killing activity of human stratum corneum. Switching into the SCV phenotype may help S. aureus to subvert cutaneous innate defense, thus contributing to the establishment and persistence of infection.
Insights
Small-colony variants (SCVs) of Staphylococcus aureus show reduced susceptibility to skin antimicrobial peptides (AMPs) and stratum corneum. This SCV phenotype may help S. aureus evade skin defenses, leading to persistent infections.
Area of Science:
- Microbiology
- Dermatology
- Infectious Diseases
Background:
- Staphylococcus aureus commonly colonizes human skin but can cause severe infections.
- Small-colony variants (SCVs) of S. aureus are linked to persistent, relapsing, and treatment-refractory infections.
Purpose of the Study:
- To investigate if skin-derived antimicrobial peptides (AMPs) have reduced activity against S. aureus SCVs.
- To determine if the SCV phenotype decreases S. aureus susceptibility to the killing activity of human stratum corneum.
Main Methods:
- Comparison of bactericidal activity of human skin-derived AMPs against clinically derived S. aureus SCVs and their isogenic wild-type strains.
- Assessment of AMP susceptibility in a S. aureus hemB mutant with the SCV phenotype versus its complemented mutant.
- Evaluation of S. aureus SCV resistance to the killing activity of human stratum corneum.
Main Results:
- Clinically derived S. aureus SCVs demonstrated reduced susceptibility to the bactericidal effects of various human skin-derived AMPs compared to their wild-type counterparts.
- A S. aureus hemB mutant exhibiting the SCV phenotype showed decreased susceptibility to AMPs relative to its hemB-complemented mutant.
- S. aureus SCVs exhibited increased resistance to the killing activity of human stratum corneum.
Conclusions:
- The SCV phenotype in S. aureus may contribute to subverting cutaneous innate defense mechanisms.
- This reduced susceptibility to AMPs and stratum corneum killing activity could facilitate the establishment and persistence of S. aureus skin infections.
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