Evaluation of Biofilm Formation in Methicillin ResistantStaphylococcus aureus isolated from human

Background and Aim : Antibiotic resistance and biofilm formation ability is one of the survivalstrategies in human pathogenic Staphylococcus aureus, which by affecting different parts of thebody, causes high costs and prolongs the patient's treatment period. The aim of this study was todetermine methicillin-resistant S. aureus (MRSA) in body fluids of patients referred to Tabrizhospitals by PCR method and the evaluated of biofilm formation in those isolates with the aim ofdetermining the relationship between biofilm formation and methicillin resistance.Methods : For this purpose, ۷۰ swab samples of body fluids were collected from differenthospitals. For initial detection of S. aureus biochemical tests were used and PCR test withamplification of nuc gene was used to confirm the diagnosis. To identify MRSA isolates, afragment of the mecA gene was amplified. Microtiter plate method was used to evaluate thebiofilm production.Results : From the ۷۰ samples, ۴۵ S. aureus (۶۴.۲۸%) were isolated by biochemical and moleculartests. The results of mecA gene amplification showed that from ۴۵ confirmed isolates of S. aureus,۲۳ isolates (۵۱.۱۱%) contained mecA gene. Data obtained from biofilm formation results showedthat ۳۱ isolates (۶۸.۸۸%) of S. aureus were able to produce biofilms with different degrees. Intotal, out of ۳۱ clinical isolates, ۲۲.۲۲% (n = ۱۰) of isolates were able to produce strong biofilm,۲۸.۸۸% (n = ۱۳) of isolates were moderate biofilm and ۱۷.۷۷% (n = ۸) of isolates were poor biofilmproducers. Of the ۲۳ isolates of MRSA, all isolates (۱۰۰%) were able to produce biofilms. In total,out of ۱۰ strong biofilm-producing isolates, ۹ isolates belonged to methicillin-resistant isolates,and among the moderate and weak biofilm-producing isolates, ۱۲ and ۲ isolates belonged tomethicillin-resistant isolates, respectively.Conclusion : Overall, the results of the present study show that most strains of S. aureus isolatedfrom various cases of clinical infections in humans are resistant to the methicillin which can berelated to the production of isolates biofilms. Therefore, the results of this study can help in theaccurate selection of appropriate antibiotics in treatment and prevent further spread of antibioticresistance in bacteria.

کلیدواژه ها:

Antibiotic resistance ، Biofilm ، mecA gene ، Methicillin ، Staphylococcus aureus