Molecular study of the biofilm formation associated with methicillin-resistance of Staphylococcus aureus isolated from clinical samples

In this study, 132 samples were collected from different clinical sources. All samples were collected from Al-Imam Al-Sadiq Teaching Hospital and Mirjan Teaching Hospital in Babylon Governorate during the period from June to September 2022. Only 36 isolates were confirmed to be Staphylococcus aureus by biochemical tests, Vitek-2 detection, and molecular diagnosis using the 16SrRNA gene. Methicillin-resistant S. aureus was phenotypically identified by methicillin disc assay and genetically confirmed by the mecA gene, all 36 were methicillin-resistant and possessed the mecA gene. The results of the antimicrobial resistance test by the disc diffusion method showed for 7 antibiotics from different groups, that 36 (100%) isolates are resistant to Methicillin and Penicillin, 33 (91.66%) isolates are resistant to Erythromycin, 21 (58.33%) isolates are resistant to Tetracycline, 18 (50%) isolates are resistant to Ciprofloxacin and Gentamicin, and 6 (16.66%) isolates are resistant to Clindamycin. The prevalence of biofilm producer bacterial isolates was 27 (75%); 6 (16.66%) produced strong biofilm, 21 (58.33%) produced moderate biofilm, and 9 (25%) isolates produced non/weak biofilm. Molecular detection results for clfA, icaA, and bbp genes responsible for biofilm formation showed that bacterial isolates possessed them by 41.66%, 50%, and 0%, respectively.