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Vancomycin tolerant, methicillin-resistant Staphylococcus aureus reveals the effects of vancomycin on cell wall

Vicenta Cázares-Domínguez1, Ariadnna Cruz-Córdova1, Sara A Ochoa1

  • 1Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.

Plos One
|March 21, 2015
PubMed

Insights

Vancomycin-tolerant MRSA (Methicillin-resistant Staphylococcus aureus) in children shows thicker cell walls, indicating adaptive resistance. This finding is crucial for understanding and treating persistent MRSA infections.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pathogen Resistance

Background:

  • Methicillin-resistant Staphylococcus aureus (MRSA) is a significant opportunistic pathogen causing various infections.
  • Increasing vancomycin resistance necessitates understanding resistance mechanisms in MRSA.
  • Vancomycin tolerance (VT) and heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotypes are growing concerns.

Purpose of the Study:

  • To investigate the impact of vancomycin on cell wall thickening in clinical vancomycin-tolerant MRSA isolates from pediatric patients.
  • To characterize the genetic and phenotypic traits of these vancomycin-tolerant MRSA isolates.

Main Methods:

  • Isolation and characterization of vancomycin-tolerant MRSA from pediatric clinical samples.
  • Multiplex-PCR for agr group and SCCmec typing.
  • Pulsed-field gel electrophoresis (PFGE) for genetic relatedness.
  • Transmission electron microscopy (TEM) to analyze cell wall thickness.

Main Results:

  • 12% of MRSA isolates were vancomycin-tolerant (VT-MRSA), with 41.66% exhibiting the hVISA phenotype.
  • VT-MRSA isolates were predominantly associated with agr group II (66.66%) and SCCmec group II (83.3%).
  • TEM analysis revealed a significant average increase of 24 nm (105.55%) in cell wall thickness in VT-MRSA compared to controls.

Conclusions:

  • Thickened cell walls in VT-MRSA, particularly those with agr type II and SCCmec group II, are linked to adaptive vancomycin resistance.
  • These findings highlight a potential mechanism for vancomycin tolerance in pediatric MRSA infections.
  • Understanding cell wall alterations is critical for developing strategies against resistant MRSA strains.

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