A New Approach to Identify and Determine the Relationship between MecA Gene Mutations Based on HRM with Clinical Species in Staphylococcus aureus Isolates

Gene mutation in Staphylococcus aureus is one of the most important causes of antibiotic-resistant strains. The High Resolution Melting Curve (HRM) analysis of DNA method can detect these mutations very high quality. The purpose of this study was to evaluate the role of clinical sample type in the occurrence of nucleotide mutations in the mecA gene of S. aureus by HRM method. In this experimental study, 43 clinical isolates of S. aureus were used. To detect possible mutations, isolates with mecA gene were replicated and sequenced. Then, analysis was performed using StepOne Software v2.3 and HRM v3.0.1 software. Sequencing results were used as gold-standard. This study with research ethics code IR.UMSHA.REC.1396.637 has been approved by research ethics committee at Hamadan University of Medical Sciences. Of 43 clinical isolates of S. aureus, 11 isolates (25.58%) had mecA gene and 32 isolates (47.41%) lacked the mecA gene. According to different clinical samples, 3 isolates (27.27%) were resistant to methicillin from blood samples, 2 isolates (18.18%) from urine specimens, 2 isolates (18.18%) from wound samples, 2 isolates (18.18%) of the catheter samples, 1 isolate (9.09%) of the abscess and 1 isolate (9.09%) were separated from the nose swab. In the meanwhile, isolates from the wound and urine had the highest mutation in the adenine amino acid as A → T, A → G, A → C, and A → X. Isolates taken from blood have mutations in Guanine amino acid as G → A. There was a significant relationship between type of mutation and type of clinical specimen in methicillin-resistant Staphylococcus aureus isolates.