Bacteriological and molecular study of some biofilm genes in clinical and environmental methicillin resistant staphylococcus aureus in Iraq

The biofilm-forming ability and inconsistent antibiotic resistance of Methicillin-Resistant Staphylococcus aureus (MRSA) strains hinder the healing of chronic wounds, thereby complicating treatment strategies and posing a serious threat to healthcare systems worldwide. This study aims to identify and eliminate Staphylococcus aureus from hospital environments and infection spectra, as well as to investigate antibiotic resistance in its isolates. Additionally, the biofilm-producing capacity of S. aureus strains was evaluated using the microtiter plate (MtP) method, and methicillin resistance was detected through the presence of the mecA gene using PCR. Furthermore, biofilm-associated genes (icaA, icaB, fnbA, fnbB, and eno) were also examined using PCR techniques. Standard culture media preparation protocols were followed, including sterilization and pH adjustment. Clinical samples were collected from patients and various hospital departments and analyzed for Staphylococcus aureus using both conventional and PCR based methods. Identification was performed via Gram staining, biochemical tests, and the VITEK-2 GP system. Antibiotic susceptibility testing was conducted using the Kirby Bauer disk diffusion method. Biofilm formation was assessed using the microtiter plate method. Finally, DNA was extracted from S. aureus strains using commercial kits, and the presence of mecA, icaAB, fnbA, and fnbB genes was determined via PCR. Biofilm formation varied among clinical and environmental Staphylococcus aureus isolates, largely depending on the activity of certain biofilm-related genes such as the icaAB locus. Among a total of 857 MRSA isolates, 48.57% were positive for the mecA gene. This gene conferred methicillin resistance in 56.70% of the isolates. On the other hand, lower resistance levels were observed for Vancomycin and Meropenem. Detection of S. aureus antigens yielded positivity rates of 40% in clinical samples and 30% in environmental samples.