Objective: Antimicrobial resistance (AMR) is a major global public health challenge that contributes to increased morbidity and mortality from infectious diseases. In India, AMR surveillance data are largely derived from tertiary care hospitals, while evidence from secondary care settings remains limited. District-level data are particularly scarce, restricting the utility of national antibiograms for local clinical decision-making. The aim of this study was to describe the antimicrobial susceptibility patterns of aerobic bacterial isolates in a resource-constrained secondary care hospital in Karaikal, India, over three years (2020-2022).

Patients and Methods: This retrospective observational study analyzed data from 1,989 clinical samples processed at the Government General Hospital, Karaikal. Of these, 763 clinically significant aerobic bacterial isolates were identified and subjected to antimicrobial susceptibility testing using standard disc diffusion methods. Susceptibility data were retrieved from microbiology laboratory registers and analyzed descriptively.

Results: The most frequently isolated organisms were Escherichia coli (24.8%), Staphylococcus aureus (18.7%), Pseudomonas aeruginosa (11.3%), and Klebsiella pneumoniae (8.4%). E. coli showed low susceptibility to ampicillin (6%), ceftriaxone (13%), and ciprofloxacin (24%). S. aureus showed ciprofloxacin susceptibility of 39%, while susceptibility to linezolid remained high (98%). P. aeruginosa demonstrated low susceptibility to gentamicin (29%). K. pneumoniae showed moderate susceptibility to piperacillin-tazobactam (56%) and meropenem (43%).

Conclusions: This study demonstrates low susceptibility to several commonly used antibiotics in a secondary care hospital setting. These findings underscore the need for strengthened local AMR surveillance, development of hospital-specific antibiograms, and implementation of context-appropriate antimicrobial stewardship and infection control strategies to guide rational antibiotic use in this region.