Antimicrobial Susceptibility Patterns Across Clinical Isolates in A Tertiary Center

Background: Antimicrobial resistance (AMR) has become a major global public health concern, particularly in tertiary care hospitals where extensive antibiotic use and invasive procedures promote the emergence of multidrug-resistant organisms. Continuous surveillance of antimicrobial susceptibility patterns is essential for guiding empirical therapy, improving antimicrobial stewardship, and preventing the spread of resistant pathogens. Methods: A prospective observational study was conducted in the Department of Microbiology at Government Medical College, Quthbullapur, Medchal–Malkajgiri, from November 2025 to February 2026. Clinically significant bacterial isolates obtained from various clinical specimens including blood, pus, respiratory samples, urine, and genital specimens were included. Bacterial identification was performed using standard microbiological techniques. Antimicrobial susceptibility testing was carried out by the Kirby–Bauer disc diffusion method according to CLSI guidelines. Resistance mechanisms such as ESBL, carbapenemase production, methicillin resistance, and vancomycin resistance were identified using phenotypic methods. Results: Gram-negative organisms including Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa predominated among isolates. High resistance rates were observed for beta-lactams (72%), aminoglycosides (68%), and carbapenems (65%). Acinetobacter species showed the highest resistance prevalence (75%). Among Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and vancomycinresistant Enterococcus were notable. Colistin and linezolid retained comparatively better activity against multidrug-resistant isolates. Conclusion: The study highlights a high prevalence of multidrug-resistant pathogens in a tertiary care setting. Regular surveillance of antimicrobial susceptibility patterns and implementation of effective antimicrobial stewardship programs are crucial to optimize treatment and control the spread of resistant organisms.