SCCmec, or staphylococcal cassette chromosome mec, is a mobile genetic element of Staphylococcus

Staphylococcus

Staphylococcus is a genus of Gram-positive bacteria. Under the microscope they appear round , and form in grape-like clusters....

 bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l species. This genetic sequence includes the mecA gene coding for resistance to the antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 methicillin

Methicillin

Meticillin or methicillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It should not be confused with the antibiotic metacycline.-History:Methicillin was developed by Beecham in 1959...

 and is the only known way for Staphylococcus strains to spread the gene in the wild by horizontal gene transfer

Horizontal gene transfer

Horizontal gene transfer , also lateral gene transfer , is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism...

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Classification

Not all SCCmec elements are identical (in fact, SCC elements without the mecA gene do exist.) SCCmec elements have been classified into five types (I through V) on the basis of two specific regions of their nucleotide sequences. One region is the mec complex including the mecA gene. The other is the ccr gene complex including genes coding for recombinases.

The mec complex is divided further into five classes (A through E) based on the arrangement of regulatory genetic features such as mecR1, an inducer

Inducer

In molecular biology, an inducer is a molecule that starts gene expression.For a gene to be expressed, its DNA sequence must be copied to make a smaller, mobile molecule called messenger RNA , which carries the instructions for making a protein to the site where the protein is manufactured...

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Distribution

The SCCmec found in methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus is a bacterium responsible for several difficult-to-treat infections in humans. It is also called multidrug-resistant Staphylococcus aureus and oxacillin-resistant Staphylococcus aureus...

 likely originated in coagulase

Coagulase

Coagulase is a protein produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates. Coagulase negativity excludes S. aureus. That is to say, S...

-negative staphylococcal species and was acquired by S. aureus

Staphylococcus aureus

Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

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Staphylococcal strains isolated from pig farms were found to carry several different types of SCCmec, suggesting that they may serve as a reservoir of these elements.