ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF STAPHYLOCOCCUS AUREUS IN NOSOCOMIAL INFECTION

Background: The global rise of methicillin-resistant Staphylococcus aureus (MRSA) has become a major public health concern due to its ability to resist multiple antibiotics, leading to increased hospital stays, costs, and mortality. Healthcare-associated infections caused by resistant strains of S. aureus are particularly concerning in clinical settings where vulnerable patients are at risk of severe complications. Objective: To determine the antimicrobial susceptibility patterns of Staphylococcus aureus isolated from clinical specimens at Chaudhry Muhammad Akram (CMA) Hospital in Lahore. Methods: This cross-sectional study included 150 clinical samples collected from hospitalized patients at CMA Hospital. Samples were obtained from blood, urine, wound swabs, sputum, and other infected body sites. S. aureus was isolated and identified using standard microbiological procedures including Gram staining, culture on selective media, and biochemical tests. Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disc diffusion method, following Clinical and Laboratory Standards Institute (CLSI) guidelines. The prevalence of MRSA and MSSA strains was recorded and resistance patterns to commonly used antibiotics were analyzed. Results: Out of 150 isolates, 58 (38.7%) were identified as MRSA, while 92 (61.3%) were MSSA. The highest resistance was observed against pipemidic acid and penicillin, both at 100%. Resistance rates for other antibiotics included amikacin (79%), gentamicin (21.62%), piperacillin/tazobactam (11%), imipenem (5%), and meropenem (7.5%). Linezolid showed complete sensitivity (0% resistance), making it the most effective agent against both MRSA and MSSA strains. Conclusion: The study highlights alarmingly high resistance rates of S. aureus to several first-line antibiotics, particularly penicillin and amikacin. Linezolid demonstrated excellent efficacy and remains a reliable therapeutic option. These findings underscore the need for continuous antimicrobial surveillance and strict stewardship policies to manage nosocomial infections effectively.