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Updated: May 12, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
Published on: February 9, 2011
Molecular and phenotypic characterization of methicillin-resistant Staphylococcus aureus from surgical site
Giovanna Pulcrano1, Antonio Vollaro, Fabio Rossano
1Department of Cellular and Molecular Biology and Pathology Luigi Califano, University of Naples Federico II, Naples, Italy. giovannapulcrano@libero.it
Background:
Nosocomial infections represent an important problem for the health of hospitalized patients. Peri-operative infections--those occurring during surgery or in the post-operative period--account for 15%-20% of cases. Most surgical site infections (SSIs) are caused by endogenous gram-positive microorganisms, in particular, Staphylococcus aureus, S. epidermidis, and other coagulase-negative staphylococci that are part of the flora of the skin.
Methods:
A retrospective study was conducted from January 2006 to December 2010 to describe the epidemiology of methicillin-resistant S. aureus (MRSA) in SSIs. The MRSA isolates were analyzed by a combination of two genotyping methods: SCCmec and pulsed-field gel electrophoresis (PFGE). Also, biofilm-forming ability was analyzed for all isolates as an indicator of their ability to persist despite antibiotic treatment.
Results:
During the study period, 1,793 swabs from SSIs were analyzed, and S. aureus was identified in 318/987 positive specimens (32%). Methicillin resistance was observed in 10% of the S. aureus isolates (n=33). Analysis by PFGE revealed that isolates with the same SCCmec type were unrelated. Instead, biofilm-forming ability tests showed that SCCmec type I MRSA had the highest ability to form a film.
Conclusions:
The strains analyzed in our study showed a homogeneous pattern of SCCmec type. The difference in ability to produce biofilm between strains of SCCmec type I and isolates with other SCCmecs was substantial. This virulence factor could have critical implications for the formation and persistence of chronic SSIs.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) strains with SCCmec type I showed a significant ability to form biofilms, potentially leading to persistent surgical site infections (SSIs). This finding highlights a key virulence factor in MRSA infections.
Area of Science:
- Infectious Diseases
- Microbiology
- Genetics
Background:
- Nosocomial infections are a significant healthcare concern, with surgical site infections (SSIs) accounting for 15-20% of cases.
- Gram-positive bacteria, particularly Staphylococcus aureus, are common causes of SSIs, originating from the patient's own skin flora.
Purpose of the Study:
- To investigate the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in SSIs.
- To analyze the genotyping and biofilm-forming capabilities of MRSA isolates from SSIs.
Main Methods:
- Retrospective study of 1,793 SSI swabs from 2006-2010.
- MRSA isolates were genotyped using SCCmec typing and pulsed-field gel electrophoresis (PFGE).
- Biofilm-forming ability was assessed for all MRSA isolates.
Main Results:
- Staphylococcus aureus was identified in 32% of positive SSI specimens.
- Ten percent of S. aureus isolates were methicillin-resistant (MRSA).
- SCCmec type I MRSA isolates demonstrated a substantially higher ability to form biofilms compared to other SCCmec types.
Conclusions:
- MRSA strains from SSIs exhibited a homogeneous SCCmec type pattern.
- The enhanced biofilm-forming capacity of SCCmec type I MRSA is a critical virulence factor.
- This biofilm formation may contribute to the development and persistence of chronic SSIs.
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