Frequency of aminoglycoside resistance and distribution of resistance genes in members of the Staphylococcus sciuri group

  • Tomasz Hauschild, Department of Microbiology, Institute of Biology, University of Bialystok, Bialystok, Poland
  • Ivana Dakic, Department of Bacteriology, Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Belgrade, Yugoslavia
  • Srdjan Stepanovic, Department of Bacteriology, Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Belgrade, Yugoslavia
  • Dragana Vukovic, Department of Bacteriology, Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Belgrade, Yugoslavia
  • Petr Jezek, Czech Republic
  • Stefan Schwarz, Institute of Farm Animal Genetics, Friedrich-Loeffler Institute (FLI), Neustadt-Mariensee, Germany

    • Objectives: Aminoglycoside antibiotics play an important role in the therapy of staphylococcal infections in humans as well as in animals. The present study investigated the prevalence of aminoglycoside resistance and genes encoding aminoglycoside modifying enzymes (AMEs) in members of the Staphylococcus sciuri group.
    Methods: A total of 304 S. sciuri group member isolates from humans, animals, food, out-hospital and hospital environment were examined for their susceptibility to amikacin, gentamicin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, streptomycin, and tobramycin by the disk diffusion method. Susceptibility to gentamicin and streptomycin was also tested by agar dilution. The presence of the major genes encoding AMEs was detected by PCR.
    Results: The overall prevalence of resistance to aminoglycosides was low at 12.1%. Eighteen isolates were resistant only to streptomycin, 15 to other aminoglycosides, and 4 isolates displayed combined resistance to streptomycin and non-streptomycin aminoglycosides. The aac(6')-Ie/aph(2''), ant(4')-Ia, and aph(3')-IIIa genes, either alone or in combination, were found in 16 out of 19 isolates showing resistance to non-streptomycin aminoglycosides. This indicates that other genes or novel variants of known genes may also be involved in resistance to non-streptomycin aminoglycosides. Among the 22 isolates that showed resistance to streptomycin, the genes str and ant(6)-Ia were detected in 18 and 4 isolates, respectively.
    Conclusions: Despite the overall low prevalence of aminoglycoside resistance, a number of different genes in different combinations were detected among the S. sciuri isolates investigated in this study.