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Updated: Jul 10, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
Published on: February 9, 2011
Staphylococcus aureus virulence factors associated with infected skin lesions: influence on the local immune response
Patricia M Mertz1, Tatiana C P Cardenas, Richard V Snyder
1Miami Dermatology Research Institute, Miami, Florida, USA.
Objectives:
To evaluate Staphylococcus aureus isolates from infected skin lesions for their potential to produce immune system-modulating toxins and to correlate these with white blood cell (WBC) counts associated with these lesions.
Design:
Specimens were obtained for bacterial culture and gram staining from 105 infected skin lesions, and the number of WBCs per low-power field (LPF) was determined. Chromosomal DNA was prepared from 84 bacterial isolates and subjected to real-time polymerase chain reaction analysis to determine the presence of genes encoding potential immunomodulating toxins. Bacterial populations were divided into 2 groups: those associated with low WBC counts (0-5 WBCs/LPF) and those with high WBC counts (> 5 WBCs/LPF). We applied chi(2) statistical analyses to compare the toxin gene profiles associated with WBC counts on initial swab for culture.
Patients:
Samples were obtained from patients at a single geographic location.
Results:
A higher than expected percentage of bacteria capable of producing the exfoliative toxins A and/or B (ETA and/or ETB) and Panton-Valentine leukocidin (PVL) was seen in all skin lesions infected with S aureus without regard to WBC count with initial cultures. Comparison of the toxins associated with the low WBC group vs the high WBC group showed that low WBC counts were associated with ETA and ETB, while high WBC counts were associated with PVL and toxic shock syndrome toxin. There were no differences in the clinical appearance of the lesions between groups.
Conclusions:
Staphylococcus aureus virulence factors ETA, ETB, and PVL are associated with WBC counts from infected skin lesions. The exact role they play in affecting the WBC counts remains to be determined.
Insights
Staphylococcus aureus skin infections show specific toxin-producing bacteria linked to white blood cell (WBC) counts. Exfoliative toxins (ETA/ETB) correlate with low WBC counts, while Panton-Valentine leukocidin (PVL) links to high counts.
Area of Science:
- Microbiology
- Immunology
- Dermatology
Background:
- Staphylococcus aureus is a common cause of skin infections.
- Certain S. aureus strains produce toxins that can modulate the host immune response.
- Understanding the relationship between these toxins and the host's inflammatory response is crucial for managing skin infections.
Purpose of the Study:
- To investigate the presence of immune system-modulating toxin genes in S. aureus isolates from skin lesions.
- To correlate the identified toxin profiles with white blood cell (WBC) counts in the infected lesions.
Main Methods:
- Collected specimens from 105 infected skin lesions for bacterial culture and WBC counts.
- Utilized real-time PCR to detect toxin genes (ETA, ETB, PVL, TSST) in 84 S. aureus isolates.
- Compared toxin gene profiles between low (0-5 WBCs/LPF) and high (>5 WBCs/LPF) WBC count groups using chi-squared analysis.
Main Results:
- A high prevalence of exfoliative toxin A/B (ETA/ETB) and Panton-Valentine leukocidin (PVL) genes was observed in S. aureus isolates, irrespective of initial WBC counts.
- Low WBC counts were associated with ETA and ETB, whereas high WBC counts correlated with PVL and toxic shock syndrome toxin (TSST).
- No significant differences in the clinical appearance of skin lesions were noted between the groups.
Conclusions:
- Specific S. aureus virulence factors, including ETA, ETB, and PVL, are associated with varying WBC counts in infected skin lesions.
- The precise mechanisms by which these toxins influence WBC counts in skin infections require further investigation.
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