Frequency of Class I and II Integrons and Aminoglycoside-Resistance Genes in Clinical Isolates of Staphylococcus aureus in northern Iran

Staphylococcus aureus is known as a hospital pathogenic bacterium that can cause a wide range of infections. Aminoglycosides are one of the drugs of choice in the treatment of septicemia caused by this bacterium. The aim of this study is to investigate the level of resistance to aminoglycosides, determine the frequency of aminoglycosides modifying enzyme genes and the frequency of class I and II integrons among clinical isolates of aminoglycosides resistant S. aureus. In this study, the resistance of 200 isolates of S. aureus to aminoglycosides including gentamycin, kanamycin, amikacin and streptomycin were investigated by Kirby-Boyer disc diffusion method. The frequency of aac(6’)-Ie-aph(2”), aph(3’)-IIIa and ant(4’)-Ia  genes and and class 1 and 2 integrons in test isolates were determined by PCR. Out of 200 isolates, 134 isolates (67%) were resistant to at least one aminoglycoside. Of this number, the frequency of aac(6’)-Ie-aph(2”), aph(3’)-IIIa and ant(4’)-Ia genes were 35.07%, 29.1% and 20%, respectively. Class I and II Integrons were detected in respectively 66% and 19% of isolates. All of isolates carrying class I integron were aminoglycoside resistant and positive for aminoglycoside modifying genes. The results showed high resistance to aminoglycosides and high frequency of aminoglycoside  modifying genes in clinical S. aureus isolates carrying calss I and II integrons