MOLECULAR CHARACTERIZATION OF AMINOGLYCOSIDE RESISTANCE AMONG CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS

Background and Aim:Aminoglycosides are potent bactericidal agents that often used in combination with either a β -lactam or a glycopeptide, especially in the treatment of staphylococcal. Enzymatic inactivation of this antibiotic by cellular enzymes that modify aminoglycosides is the major mode of mechanisms for bacterial resistance to this drug. The aim of Present study was to determine the frequency of aminoglycoside-modifying enzymes (AME) encoding genes in clinical isolates of S. aureus.Methods:Two hundred thirty clinical isolates of S. aureus were collected from patients in Qazvin and Tehran educational hospitals. Antibiotic susceptibility determined by disk diffusion method according to the CLSI guideline. The gentamicin (Sigma Co) MIC was determined with agar dilution method using a range between 0.5-256 µg/ml. Aminoglycoside Modifying Enzyme ([aac(6’)-Ie-aph(2 )]، ant(4’)-Ia and aph(3’)-IIIa)genes ()was performed by PCR and sequencing.Results:Aminoglycosides resistance were detected to Kanamycin (43/8 %), Gentamicin (47 %), Tobramycin (47%), Amikacin (46/1 %), Netilmicin (26/1 %) Doxycycline (50/5 %), Ciprofloxacin (50 %), Rifampin (36/5 %), Mupirocin (9/1 %) and Teicoplanin (4/3 %). Forty four percent of strains were resistant to Gentamicin on agar dilution method. The frequency of [aac(6’)-Ie-aph(2 )]، ant(4’)-Ia and aph(3’)-IIIa genes in the isolates was determined by PCR method that 39.1 %, 6.5 % and 18.3 % reported, respectively.Conclusion:The result of this study showed that here was a high rate of aminoglycoside resistance and AME genes among S.aureus clinical isolates.

کلیدواژه ها:

Staphylococcus aureus ، AME ، [aac(6’)-Ie-aph(2 )] ، ant(4’)-Ia ، aph(3’)-III