Characterization of staphylococcus aureus based on its biofilm forming and antibiotic resistance profile

Abstract

Staphylococci aureus is the leading cause of biofilm- associated infections, community-acquired infections, and hospital-acquired infections worldwide. Methicillin-resistant Staphylococcus aureus is the major cause of healthcare-associated bacteremia in hospitals, which raises the risk of infection, morbidity, and mortality. This is especially harmful when vancomycin resistance exists. The formation of S. aureus biofilms enhances antibiotic resistance, which contributes to pathogenicity. Biofilm-forming isolates exhibit variable antibiotic sensitivity, posing challenges in treatment. In this study, 28 Methicillin-resistant Staphylococcus aureus (MRSA) were recovered from clinical samples at Al-Najaf teaching hospital using mannitol salt and Chrom agar. Cefoxitin disk diffusion method was used to detect methicillin resistance. Biofilm formation was detected using the Congo red agar technique. All 28 isolates were confirmed to be S. aureus based on mannitol salt agar growth, and all produced fermentation . Cefoxitin disc diffusion revealed 100% Methicillin resistance in S. aureus. Using the Congo red agar technique, 21/28 (75%) clinical (MRSA) isolates produced biofilm. The antimicrobial sensitivity test of MRSA isolates revealed that vancomycin was the most effective antibiotic, with an effectiveness rate of 100%. However, resistance to β-lactam antibiotics was evident in Cefepime (100%) and Cefotaxime (93%).In conclusion, our study found that a significant proportion of MRSA form biofilm. Bacterial biofilm has been shown to be far more resistant to antibiotics.