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Updated: Jan 9, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Hospital-associated MRSA genotypes causing complicated community-onset skin and musculoskeletal infections
Stefânia Bazanelli Prebianchi1,2, Ingrid Nayara Marcelino Santos1, Isabelle Caroline Frois Brasil Tannus1,2
1Special Laboratory of Clinical Microbiology (LEMC), Department of Medicine, Division of Infectious Diseases, Federal University of São Paulo (UNIFESP), Paulista School of Medicine (EPM), São Paulo, Brazil.
Objectives:
To assess clinical and epidemiological characteristics, and phenotypic and genomic risk factors associated with severity and death in complicated community-onset skin, soft tissue, and musculoskeletal infections (cSSTMIs) caused by methicillin-resistant Staphylococcus aureus (MRSA).
Methods:
Patients with cSSTMIs were investigated between June 2022 to January 2024 and followed for one month after hospital discharge. Tissue samples were obtained through biopsy, punch, or fluid aspiration. All MRSA isolates underwent genomic sequencing. Factors associated with poor outcomes were analyzed using multivariate regression analysis, complemented by penalized regression (LASSO) with stratified cross-validation and sensitivity analyses to mitigate the risk of overestimation given the limited MRSA sample size.
Results:
A total of 118 patients were studied, 60.2% male, with a mean age of 41.1 years (± SD 26.1). Recurrence and death occurred in 13.5% and 7.6% of cases, respectively. Diagnostic yielded 145 microorganisms, 61.4% were S. aureus, 24.1% being MRSA and 25.5% multidrug-resistant. Thirty-five MRSA strains belonged to clonal complexes 5, 8, and 30, with a predominance of the ST105-MRSA-II-t2 clone. Deep tissue involvement was associated with an increased likelihood of severe outcomes, with an odds ratio of 13.2 (p = 0.036), whereas penalized regression confirmed deep infection as the most stable predictor. MRSA genomic characteristics were not independently correlated with outcomes.
Conclusions:
High rates of antimicrobial resistance were observed in cSSTMIs, suggesting the need for empirical coverage, particularly in deep infections that were significantly associated with adverse outcomes.
Insights
Complicated skin infections caused by methicillin-resistant Staphylococcus aureus (MRSA) show high antimicrobial resistance. Deep tissue infections significantly predict severe outcomes and death in these MRSA cases.
Area of Science:
- Infectious Diseases
- Microbiology
- Genomics
Background:
- Complicated community-onset skin, soft tissue, and musculoskeletal infections (cSSTMIs) pose significant clinical challenges.
- Methicillin-resistant Staphylococcus aureus (MRSA) is a key pathogen in cSSTMIs, often exhibiting multidrug resistance.
Purpose of the Study:
- To investigate clinical, epidemiological, phenotypic, and genomic factors linked to severity and mortality in MRSA-caused cSSTMIs.
- To identify predictors of poor outcomes in patients with MRSA cSSTMIs.
Main Methods:
- Prospective study of 118 patients with cSSTMIs from June 2022 to January 2024.
- Genomic sequencing of MRSA isolates and multivariate regression analysis, including LASSO penalized regression, to identify risk factors.
- Analysis of clinical data, microbiological findings, and patient outcomes including recurrence and mortality.
Main Results:
- MRSA was identified in 24.1% of S. aureus isolates; 25.5% of all isolates were multidrug-resistant.
- Deep tissue involvement was a strong predictor of severe outcomes (OR=13.2, p=0.036).
- No independent correlation was found between MRSA genomic characteristics and patient outcomes.
Conclusions:
- cSSTMIs caused by MRSA exhibit high rates of antimicrobial resistance.
- Deep infections are significantly associated with adverse outcomes, necessitating prompt and appropriate empirical antimicrobial therapy.
- Genomic surveillance of MRSA strains is crucial for understanding resistance patterns and guiding treatment strategies.
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