Retrospective Analysis of Bacterial Isolates and Antimicrobial Susceptibility Patterns from Routine Clinical Specimens at a Tertiary Care Centre

Abstract

Background: Antimicrobial resistance is an increasing challenge in the management of bacterial infections and can significantly limit effective treatment options. Regular surveillance of bacterial isolates and their antimicrobial susceptibility patterns is essential for guiding empirical therapy and supporting antimicrobial stewardship. This study aimed to determine the distribution of bacterial isolates and their antimicrobial susceptibility patterns from routine clinical specimens at a tertiary care centre.

Methods: A retrospective, observational, laboratory-based study was conducted at Father Colombo Institute of Medical Sciences, Warangal, Telangana, from January to December 2025. A total of 400 non-duplicate clinically significant bacterial isolates recovered from routine clinical specimens were analyzed.

Results: Of the 400 isolates, 300 (75.0%) were Gram-negative and 100 (25.0%) were Gram-positive. Urine was the most common specimen source, accounting for 37.5% of isolates. Escherichia coli was the predominant organism (30.0%), followed by Klebsiella pneumoniae (17.5%), Staphylococcus aureus (15.0%), Pseudomonas aeruginosa (12.5%), and Acinetobacter spp. (8.8%).

Conclusion: The study demonstrated a substantial burden of antimicrobial resistance, particularly among Gram-negative organisms. Continuous local surveillance, periodic antibiograms, antimicrobial stewardship, and culture-guided therapy are essential to improve antimicrobial use and clinical outcomes.