Genetic basis of resistance to aminoglycosides in Acinetobacter spp. and spread of armA in Acinetobacter baumannii sequence group 1 in Korean hospitals

Diagn Microbiol Infect Dis. 2009 Jun;64(2):185-90. doi: 10.1016/j.diagmicrobio.2009.02.010. Epub 2009 Apr 9.


A total of 75 Acinetobacter isolates resistant to all available aminoglycosides obtained from 2 Korean hospitals were studied for the genetic basis of resistance to aminoglycosides. The MIC(50) and MIC(90) of Acinetobacter baumannii isolates (n = 61) to amikacin, gentamicin, isepamycin spectinomycin, streptomycin, and tobramycin were higher than those of Acinetobacter genomic species 13TU isolates (n = 14). Genes encoding aminoglycoside-modifying enzymes, ant(3")-Ia, aac(6')-Ib, aph(3')-1a, aac(3)-Ia, and aph(3')-VI, and 16S ribosomal RNA (rRNA) methylase armA were detected. ant(3")-Ia and aac(6')-Ib were commonly detected in both Acinetobacter spp., but armA and aph(3")-Ia were only detected in A. baumannii. armA was located on the plasmids. A. baumannii isolates carrying armA were classified into 7 pulsotypes but belonged to sequence group 1. The combination of aminoglycoside-modifying enzymes is responsible for the moderate-level resistance to aminoglycosides in Acinetobacter genomic species 13TU, whereas armA is responsible for the high-level resistance to aminoglycosides in A. baumannii sequence group 1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections / microbiology*
  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / genetics*
  • Acinetobacter baumannii / isolation & purification
  • Aminoglycosides / pharmacology*
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics*
  • Bacterial Typing Techniques
  • Cluster Analysis
  • DNA Fingerprinting
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial*
  • Electrophoresis, Gel, Pulsed-Field
  • Genotype
  • Hospitals
  • Humans
  • Korea
  • Microbial Sensitivity Tests
  • Plasmids


  • Aminoglycosides
  • Anti-Bacterial Agents
  • Bacterial Proteins
  • DNA, Bacterial