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Genetic basis of aminoglycoside resistance following changes in aminoglycoside prescription patterns

Chris Kosmidis1, Maria Giannopoulou, Anastasia Flountzi

  • 1Infectious Diseases and Antimicrobial Chemotherapy Research Laboratory, First Department of Propaedeutic Medicine, University of Athens, Greece. ckosmidis@gmail.com

Journal of Chemotherapy (Florence, Italy)
|August 3, 2013
PubMed

Insights

Reduced gentamicin use in Enterobacteriaceae infections may preserve its effectiveness. Gentamicin resistance rates decreased, while other aminoglycoside resistance remained stable, suggesting a link between usage patterns and resistance mechanisms.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Aminoglycosides (AG) are crucial for treating infections caused by multiresistant Enterobacteriaceae.
  • Institutional AG usage shifted between 1997 and 2006, with decreased use of most AG except amikacin.

Purpose of the Study:

  • To analyze changes in AG susceptibility rates in Enterobacteriaceae.
  • To correlate these changes with the prevalence of molecular resistance mechanisms.
  • To assess the impact of altered AG usage patterns on bacterial susceptibility.

Main Methods:

  • Enterobacteriaceae isolates from blood cultures (1997 and 2006) were analyzed.
  • Disk diffusion method determined AG susceptibility.
  • Polymerase Chain Reaction (PCR) identified genes encoding AG-modifying enzymes and methylases.

Main Results:

  • Gentamicin resistance rates declined from 14.5% to 8.8%.
  • Resistance rates for other AG remained unchanged.
  • The prevalence of resistance mechanisms shifted from AAC(6')-I+AAC(3)-I in 1997 to AAC(6')-I as the dominant mechanism in 2006.

Conclusions:

  • Reduced gentamicin usage may help maintain its efficacy against severe infections caused by multiresistant bacteria, including carbapenemase-producing Enterobacteriaceae.
  • Monitoring AG usage and resistance mechanisms is vital for antimicrobial stewardship.

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