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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

Capsular serotype of Staphylococcus aureus in the era of community-acquired MRSA

Deena E Sutter1, Amy M Summers, Christine E Keys

  • 1Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA. deena.sutter@amedd.army.mil

FEMS Immunology and Medical Microbiology
|June 3, 2011
PubMed

Insights

Most pediatric Staphylococcus aureus isolates carry capsule genes, but MRSA strains are often unencapsulated, with USA300 strains linked to severe infections.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pediatric Medicine

Background:

  • Capsular polysaccharide (CP) is crucial for Staphylococcus aureus pathogenicity and immunogenicity.
  • Limited data exists on common S. aureus serotypes in US pediatric patients.
  • Understanding serotype prevalence is vital for infection control and treatment strategies.

Purpose of the Study:

  • To investigate capsular serotypes of pediatric S. aureus isolates.
  • To determine methicillin susceptibility, Panton-Valentine leukocidin (PVL) presence, and clonal relatedness.
  • To correlate these factors with clinical presentation in pediatric patients.

Main Methods:

  • Clinical S. aureus isolates from pediatric patients were analyzed.
  • Methicillin susceptibility, PVL genes (lukS-PV, lukF-PV), and capsule genes (cap5, cap8) were detected using PCR.
  • Capsular/surface polysaccharide expression was assessed by agglutination; genetic relatedness by pulsed-field gel electrophoresis.

Main Results:

  • All S. aureus isolates possessed cap5 or cap8 genes.
  • 69% of isolates were methicillin-susceptible (MSSA) and mostly encapsulated.
  • 82% of MRSA isolates were unencapsulated, expressing cell wall antigen 336; USA300 (MRSA, PVL-positive) strains predominated in invasive infections.

Conclusions:

  • Pediatric S. aureus isolates uniformly carry capsule type 5 or 8 genes.
  • MSSA isolates are diverse and predominantly encapsulated.
  • Unencapsulated PVL-positive USA300 MRSA strains are significant pathogens in pediatric invasive infections.

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