DETECTION OF METHICILLIN RESISTANCE IN CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS IN TERTIARY CARE HOSPITAL, TIRUPATI

Objective: The study aimed to estimate the prevalence of methicillin resistance of Staphylococcus aureus in various clinical samples received at tertiary care hospital. Initially, the Staphylococcus aureus and its antibiotic susceptibility tests is performed in clinical samples which are submitted to the department of Microbiology. And Methicillin Resistance Staphylococcus Aureus (MRSA) is determined by using cefoxitin (30 μg) as per CLSI guidelines. Methods: The prospective study was conducted in department of Microbiology in a tertiary care hospital. All Staphylococcus aureus organisms isolated in clinical samples were included in the study and processed as per the standard operating procedure. Methicillin susceptibility was tested by using cefoxitin (30μg) disks on Muller-Hinton agar plates that were inoculated with a suspension (equal to 0.5 McFarland standards) of the s. aureus. Results: In our study, amongst hundred staphylococcus aureus isolates, sixty isolates were shown resistance to cefoxitin (30µg), which indicates that percentage of methicillin-resistant s. aureus in our study is 60. Majority of s. aureus were isolated from blood samples 44% (n= 44) followed by pus samples 32% (n=32). Linezolid resistance reported was 3%. All isolates were sensitive to vancomycin and daptomycin by disc diffusion test as per CLSI guidelines 2021. Conclusion: To conclude, MRSA plays a significant role and it can be transmitted through endogenous, cross-infection and reinfections. Phenotypic methods like use of cefoxitin disc (30µg) can be considered for detection of methicillin resistance in S. aureus, as it consumes less time and easy to perform.