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Published on: May 8, 2013

Aminoglycoside-resistance mechanisms in multidrug-resistant Staphylococcus aureus clinical isolates

R Kelmani Chandrakanth1, S Raju, S A Patil

  • 1Department of Biotechnology, Gulbarga University, Gulbarga, 585 106, Karnataka, India. ckelmani@gmail.com

Current Microbiology
|March 6, 2008
PubMed

Insights

This study investigated aminoglycoside resistance in Staphylococcus aureus. Genotypic analysis revealed specific enzyme genes correlating with varying resistance levels, suggesting adaptive resistance mechanisms.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Aminoglycoside resistance is a significant challenge in treating Staphylococcus aureus infections.
  • Understanding the genetic basis of this resistance is crucial for developing effective therapeutic strategies.

Purpose of the Study:

  • To evaluate aminoglycoside resistance in six clinical isolates of Staphylococcus aureus.
  • To correlate genotypic findings with observed resistance phenotypes.
  • To investigate potential adaptive resistance mechanisms.

Main Methods:

  • Genotypical examination to identify aminoglycoside-modifying enzyme (AME) coding genes.
  • Phenotypic evaluation of resistance to various aminoglycosides (gentamicin, streptomycin, kanamycin).
  • Transmission electron microscopy to observe cellular changes.

Main Results:

  • Three isolates possessed AME coding genes, while three lacked them.
  • Isolates with the bifunctional aac(6')-aph(2'') and aph(3')-III genes showed high-level resistance to gentamicin and streptomycin.
  • Isolates lacking AME genes exhibited low-level resistance, and electron microscopy indicated adaptive resistance changes.

Conclusions:

  • The presence and type of aminoglycoside-modifying enzyme genes directly influence resistance levels in Staphylococcus aureus.
  • Adaptive resistance mechanisms, potentially involving morphological changes, are operative in Staphylococcus aureus.
  • Genotypic and phenotypic correlations are essential for understanding and combating aminoglycoside resistance.

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