en ميکروب شناسي Microbiology تحقيقي Original Paper <strong><span dir="LTR">Background and objectives</span></strong><span dir="LTR">:</span><span dir="LTR"> <em>Staphylococcus aureus</em> is a frequent cause of hospital- and community-associated infections on a global scale. This organism is responsible for causing an extensive range of diseases and many of them are capable of biofilm formation for their survival. By this method, treatment of them with antibiotics become very difficult and antibiotic resistance is another rising concern. </span><br> <strong>Material and Methods:</strong> The clinical samples were collected and examined for <em>Staphylococcus aureus</em> by microbiological and biochemical tests. Then, the biofilm formation in <em>Staphylococcus aureus</em> isolates was detected by microtiter plate. Using SYBR Green Real-Time PCR, the expression of PSM was determined.<br> <strong>Results:</strong> A total of 60 strains of <em>Staphylococcus aureus</em> were isolated from clinical isolates. Of them, 47 strains (78.3%) were identified biofilm producing and the others were considered negative for biofilm formation. After real-time PCR testing to detect PSM, it was determined that 100% of the strains were positive for biofilms and PSM genes. The results of phenotypic and genotypic tests of biofilm were closely related to each other and the expression of <em>PSM B</em> gene was 80%. It was found that 100% of strains were biofilm producing and <em>PSM B</em> gene was present in 78.3% (47 strains) of them.<br> <strong>Conclusion: </strong>The prevalence of biofilm production in <em>Staphylococcus aureus</em> strains isolated from clinical samples was high, so it is highly important to monitor the prevalence of these organisms in hospitals and community as well as their antimicrobial resistance. PSM B gene, clinical isolates, Staphylococcus aureus, biofilm 10 14 http://mlj.goums.ac.ir/browse.php?a_code=A-10-883-1&slc_lang=en&sid=1 Ali Asghar Ayatollahi 100319475328460017164 100319475328460017164 No Medical Laboratory Sciences Research Center, Golestan University of Medical Sciences,Gorgan, Iran Abolfazl Khandan Del ab.khandandel@gmail.com 100319475328460017165 100319475328460017165 Yes Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, Iran Ailar Jamalli 100319475328460017166 100319475328460017166 No Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran Khashayar Shahin khshahin@jaas.ac.cn 100319475328460017167 100319475328460017167 No State Key Laboratory Cultivation Base of MOST, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, PR China Ania Ahani Azari ania_783@yahoo.com 100319475328460017168 100319475328460017168 No Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran