Antimicrobial Susceptibility Pattern of Staphylococcus aureus Strains Isolated from Hospitalized Patients in Tehran, Iran

Abstract

<em> Staphylococcus aureus </em>is a major bacterial pathogen that causes different<em> </em>community- and hospital-acquired infections. Over time, strains of <em>S. aureus</em> have become resistant to different antibiotics including penicillinase-resistant penicillins. Having data on the local antimicrobial susceptibility pattern of this pathogen is necessary for selection of appropriate antibiotics for empirical treatment of infections due to it. To determine the antimicrobial susceptibility pattern of <em>Staphylococcus</em> <em>aureus </em>strains isolated from hospitalized patients in Tehran, Iran, In a prospective<em> </em>cross-sectional study performed at Imam Khomeini Hospital, samples were collected from hospitalized patients and were cultured. All positive cultures which yielded <em>S. aureus </em>underwent antimicrobial susceptibility testing using the Kirby-Bauer<em> </em>disk diffusion method on Mueller-Hinton agar. The results were interpreted after 24 hours of incubation at 37 °C. A total of 160 clinical isolates of <em>S. aureus</em> were collected. Most isolates were obtained from blood (29%). The overall susceptibility of isolated <em>S. aureus</em> strains to antimicrobial agents was 100% for vancomycin, 49.4% for amikacin, 43.8% for gentamicin, 36.8% for co-trimoxazole and tetracycline, 36.3% for cefazolin, 30.6% for cephalexin, 24.4% for oxacillin, 23.8% for erythromycin, and 3.1% for penicillin. Other than vancomycin, none of the tested antibiotics are appropriate for empirical treatment of serious S .<em>aureus</em> infections in our area.