Related Experiment Video
Updated: Aug 30, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
Published on: February 9, 2011
Evolutionary models of the emergence of methicillin-resistant Staphylococcus aureus
D Ashley Robinson1, Mark C Enright
1Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom.
Abstract:
Five major lineages of methicillin-resistant Staphylococcus aureus (MRSA) have evolved since the introduction of methicillin for the treatment of infections caused by penicillin-resistant S. aureus in 1959. The clones of these lineages are responsible for the vast majority of hospital-acquired MRSA disease globally. We have constructed high-resolution evolutionary models for each lineage using a parsimony approach with 15 partial gene sequences from 147 geographically diverse isolates. On the basis of these models, we infer that MRSA has emerged at least 20 times upon acquisition of the methicillin resistance determinant, which is carried on a mobile genetic element called the staphylococcal cassette chromosome mec (SCCmec). The acquisition of SCCmec by sensitive clones was four times more common than the replacement of one SCCmec with another. Notably, SCCmec type IV was found in twice as many clones as any other SCCmec type, and it is this SCCmec type which is commonly found in clones from patients with community-acquired MRSA disease. Our findings suggest that most clones of MRSA arise by the acquisition of SCCmec type IV by methicillin-sensitive isolates.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) clones emerged at least 20 times. Most MRSA clones arise from sensitive strains acquiring SCCmec type IV, common in community-acquired infections.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genetics
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant global pathogen.
- Five major MRSA lineages cause the majority of hospital-acquired infections.
- Understanding MRSA evolution is crucial for controlling its spread.
Purpose of the Study:
- To construct high-resolution evolutionary models for major MRSA lineages.
- To investigate the emergence and evolution of MRSA clones.
- To identify key factors driving MRSA diversification.
Main Methods:
- Phylogenetic analysis using a parsimony approach.
- Examination of 15 partial gene sequences from 147 diverse MRSA isolates.
- High-resolution evolutionary modeling.
Main Results:
- MRSA has emerged at least 20 times through acquisition of the staphylococcal cassette chromosome mec (SCCmec).
- Acquisition of SCCmec by sensitive strains was four times more frequent than SCCmec replacement.
- SCCmec type IV was the most prevalent type, frequently found in community-acquired MRSA.
Conclusions:
- Most MRSA clones originate from methicillin-susceptible isolates acquiring SCCmec type IV.
- The acquisition of SCCmec, particularly type IV, is a primary driver of MRSA evolution.
- This finding has implications for understanding and combating MRSA infections.
Related Concept Videos
01:25Mechanism of Antibiotic Resistance in MRSA
01:25Clinical Significance of Antibiotic Resistance
01:29Staphylococcal Skin Infections
01:24Evolution of New Traits in Microbes
01:31Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
01:30Development of Antibiotic Resistance