Prevalence and Antimicrobial Susceptibilities of Methicillin Resistant Staphylococcus aureus Bacteraemia in Hospitalized Patients in Shiraz, Iran

Background and Objectives: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major causes of morbidity and mortality of hospital infections. In this study, we evaluated the prevalence and antibiotic resistance of MRSA, isolated from blood culture in Shiraz. Materials and Methods: A retrospective study was carried to identify the prevalence of MRSA in the blood culture isolates and their antibiotic susceptibility patterns in Nemazee Teaching Hospital from March 2018 to August 2019. S. aureus was isolated by automated blood culture system and identified by standard biochemical methods. Antibiotic susceptibility testing was performed by Kirby Bauer Disk Diffusion method, according to the Clinical and Laboratory Standards Institute guidelines. Methicillin resistance was detected using cefoxitin (30 μg) disc. Screening of clinical S.aureus isolates for vancomycin resistance was done on brain heart infusion agar containing vancomycin, 6 mg/mL. Results: In our study, out of 108 S. aureus, 24.5% were MRSA, however, during 2014–2018 rates of MRSA bloodstream infection were around 45%. All the strains were sensitive to Linezolid and Vancomycin. The strains were highest resistant to Penicillin and Cephalexin. Conclusion: Although MRSA bacteremia incidence has decreased in the current study, compared to previous years, regular surveillance studies in different hospitals and centers is necessary, so that adequate measures to prevent and control spreading of resistant strains should be taken regularly.