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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

Published on: May 8, 2013

Genetic Characterization of Methicillin Resistant and Sensitive, Vancomycin Intermediate Staphylococcus aureus

Seyed Asghar Havaei1, Amir Azimian, Hosein Fazeli

  • 1Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, P.O. Box 73461-8174, Isfahan, Iran.

ISRN Microbiology
|June 14, 2013
PubMed

Insights

Vancomycin resistance in Staphylococcus aureus is a growing concern. This study found intermediate vancomycin resistance in both MRSA and MSSA strains, suggesting a concerning trend in antibiotic resistance.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Antimicrobial Resistance

Background:

  • Rising global reports of Vancomycin Intermediate Staphylococcus aureus (VISA) and Vancomycin Resistant Staphylococcus aureus (VRSA) threaten vancomycin's efficacy.
  • Epidemiological surveillance is crucial for informing global healthcare policies regarding antibiotic resistance.
  • Staphylococcus aureus poses a significant public health challenge due to its evolving resistance patterns.

Purpose of the Study:

  • To evaluate the prevalence of vancomycin and methicillin resistance in Staphylococcus aureus isolates.
  • To characterize the genetic and molecular features of vancomycin-intermediate strains.
  • To investigate the association of VISA with both Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Susceptible Staphylococcus aureus (MSSA).

Main Methods:

  • Collection of 171 Staphylococcus aureus isolates from clinical samples in Iran.
  • Antimicrobial susceptibility testing using agar screening, disk diffusion, and MIC methods.
  • Genetic analysis including mecA, vanA genes, SCCmec, agr, spa typing, toxin profiling, and Multilocus Sequence Typing (MLST).

Main Results:

  • 67% of Staphylococcus aureus isolates exhibited resistance to methicillin (MRSA).
  • Five isolates (2.9%) displayed intermediate resistance to vancomycin (VISA).
  • Two VISA isolates were identified as MSSA-VISA, diverging from the typical association with MRSA.

Conclusions:

  • The study identified a concerning prevalence of methicillin resistance and vancomycin intermediate resistance in Staphylococcus aureus.
  • The emergence of MSSA-VISA strains suggests a potential parallel increase in vancomycin resistance among susceptible strains.
  • Genetic analysis indicated that the isolated VISA strains represent endemic Asian clones, highlighting the need for continued surveillance and targeted interventions.

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