Phenotypic and Genotypic Detection of Biofilm Formation in Methicillin-Resistant Staphylococcus Aureus Isolated from Diabetic Foot Infections
Abbas Hussein AlSalami, Majida Malik Meteab Alshammari,
Majid Hadi AlKalabi
Methicillin-resistant S. aureus biofilm formation is a common isolate in diabetic foot infections; biofilm development contributes significantly to the pathophysiology and reduces antibiotic sensitivity, making treatment challenging. To identify methicillin-resistant S. aureus in infected diabetic feet, their antibiotic susceptibility, and their phenotypic and genotypic capacity for biofilm formation. Materials and methods: A cross-sectional study was conducted from August 2023 to January 2024 at Al-Manathira General Hospital in the Najaf, Iraq. Patients with diabetic foot infections were enrolled in the study. Data regarding the age, sex, residence, antibiotic treatment, smoking, and past medical history were recorded for each participant. The disk diffusion technique was used to determine the existence of methicillin resistance. Cefoxitin disks were used for this purpose. The antibiotic susceptibility of the isolates was tested by the VITEK® 2 system. Biofilm production was assessed using the microtiter plate method. Polymerase chain reaction was used to identify the presence of the icaD gene in the bacterial strains. Out of 150 patient samples, there were 102 S. aureus isolates (93.1% were MRSA, and 6.9% MSSA). Many S. aureus isolates demonstrated resistance to beta-lactam antibiotics and fusidic acid. In contrast, a smaller percentage of MRSA isolates resisted vancomycin and trimethoprim/sulfamethoxazole. No isolates were resistant to linezolid or tigecycline. All MRSA isolates produced biofilm with varying degrees: strong 27.4%, moderate 41.2%, and weak 31.4% respectively. Detection of the icaD gene, signifying biofilm-forming capability, was remarkably high (90.19%) among MRSA isolates. This study indicated that methicillin-resistant isolates developed more biofilms and were highly resistant to most drugs. The high prevalence of the biofilm icaD gene in multidrug-resistant S. aureus underscores the need for a thorough knowledge of its epidemiology, molecular study, and effective biofilm therapy for S. aureus infection.
Keywords: Diabetic foot, MRSA, Biofilm-related genes, Antibiotic resistance
