Comprehensive study of Phenotypic and Genotypic Characteristics in MDR MRSA from clinical sources

Staphylococcus aureus is a leading pathogen responsible for conditions such as pneumonia, osteomyelitis, septicemia, soft-tissue infections, and other skin infections. Its pathogenicity stems from various virulence factors, some of which are acquired, particularly antibiotic resistance. One hundred thirty pathogenic samples were collected from patients at the Ramadi Hospitals in Iraq. The sample collection period was between August and October 2024; a total of 116 bacterial isolates were collected. From these, 20 MDR MRSA isolates were selected for further analysis. Characterization was performed using standard procedures validated by the OXDD, FOXDD, and VITEK 2 Compact Systems, as well as 16S rRNA gene amplification and detection of virulence factors. Biofilm production was assessed using the 96-well microtiter plate and tube method, as well as CRA and MCRA. The existence of genes such as mecA, femA, clfA, and icaA was assessed through PCR. All 20 isolates exhibited MDR to beta-lactam, glycopeptide, tetracycline, aminoglycoside, lincosamide, macrolide, fluoroquinolone, and sulfonamide antibiotics, with 100% resistance to penicillin and macrolide antibiotics. Most isolates exhibited favorable results for their virulence factors, showing hemolysis of blood and generating deoxyribonuclease, urease, gelatinase, lecithinase, and protease. Biofilm production was diverse across isolates, which were characterized as strong (5, 25%), moderate (4, 20%), and weak (11, 55%), as demonstrated by black, dry, crystalline colonies on CRA and MCRA. This study provides a comprehensive characterization of (MRSA) in Ramadi city, Iraq, indicating high levels of multidrug resistance, various virulence factors, and a high propensity to form biofilms. These findings highlight the urgent need for highly effective strategies to combat this bacterium. Staphylococcus aureus remains a highly virulent, multidrug-resistant pathogen with strong biofilm-forming ability, underscoring the critical need for alternative therapeutic approaches and improved infection control strategies.