Virulence properties of Staphylococcus aureus in clinical, colonizing, and environmental isolates

Introduction : Staphylococcus aureus ( S. aureus ) can grow without oxygen and often lives in the nose, skin, and other areas. This can cause localized or generalized infections. It is associated with hospital-acquired infections, and the rise of methicillin resistance makes treatment difficult. We characterized S. aureus isolates from patients, healthy carriers, and the environment. Materials and methods: A total of 100 S. aureus isolates, including 50 clinical, 40 colonizing, and 10 environmental samples, were included in the study. The presence of antibiotic resistance, virulence factors, and associated genes was determined. Results : Based on cefoxitin resistance, 46 isolates were identified as MRSA and 54 as MSSA. Only 36 and 27 possessed the mecA gene in MRSA and MSSA isolates, respectively. Among clinical isolates, 71% tested positive for Panton-Valentine leukocidin (PVL), 64% for α-hemolysin (Hla), 92% for fibronectin-binding protein A (FnbA), and 61% for staphylococcal protein A (SpA). For surveillance isolates, the rates were lower, with PVL at 25.8%, Hla at 26.4%, FnbA at 42.4%, and SpA at 35.7%. Among environmental isolates, PVL was observed in 3.2%, Hla in 9.4%, FnbA in 9.8%, and SpA in 14%. Conclusion : MRSA isolates with virulence properties are seen in the hospital and are difficult to treat, leading to morbidity and mortality. We need efficient infection control and surveillance strategies to monitor and control its transmission. Availability of over-the-counter antibiotics should be discouraged so that MRSA can be controlled, if not eradicated.