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Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
09:03

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus

Published on: September 5, 2013

A novel type-III staphylococcal cassette chromosome mec (SCCmec) variant among Indian isolates of

Gayathri Arakere1, Savitha Nadig, Teruyo Ito

  • 1Sir Dorabji Tata Centre for Research in Tropical Diseases, Innovation Centre, Indian Institute of Science Campus, Bangalore, India. gayathri.arakere@gmail.com

FEMS Microbiology Letters
|February 4, 2009
PubMed

Insights

A novel staphylococcal cassette chromosome mec (SCCmec) type-III element was found in Indian methicillin-resistant Staphylococcus aureus (MRSA) strains. This discovery reveals a new MRSA clone distinct from typical nosocomial strains.

Area of Science:

  • Microbiology
  • Genetics
  • Infectious Diseases

Background:

  • Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global health threat.
  • Staphylococcal cassette chromosome mec (SCCmec) elements are key determinants of MRSA.
  • Understanding SCCmec diversity is crucial for tracking MRSA evolution and spread.

Purpose of the Study:

  • To characterize a novel SCCmec element identified in MRSA strains from an Indian hospital.
  • To investigate the genetic makeup and clonal lineage of these MRSA isolates.
  • To differentiate this novel MRSA clone from other nosocomial MRSA strains.

Main Methods:

  • Pulsed-field gel electrophoresis (PFGE) and spa typing for clonal analysis.
  • Multiplex PCR to identify specific genetic elements (e.g., mer operon, transposases).
  • Long-range PCR and nucleotide sequencing to determine the SCCmec region structure.

Main Results:

  • Eight MRSA strains from India carried a novel type-III SCCmec element.
  • These strains, though ST239 and spa t037, exhibited lower MICs than typical type-III MRSA.
  • The novel SCCmec contained a unique 422 bp sequence, mer operon, and pT181 plasmid, integrated via IS431.
  • An SCC-like element was found downstream of the type-III SCCmec.

Conclusions:

  • A novel MRSA clone carrying a unique SCCmec type-III element has been identified in India.
  • This clone belongs to the ST239 genotype but possesses distinct genetic features and antibiotic susceptibility profiles.
  • The findings highlight the ongoing evolution of MRSA and the emergence of new genetic variants.

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