Occurrence of non-fermenting gram negative bacilli and their drug resistance crisis along with developing superbug problem: Experience in medical college Kolkata, India
Abstract
Background: Non-fermenting Gram-negative bacilli (NFGNB) are emerging as an important nosocomial pathogens with significant multidrug resistance simultaneously posing a serious global health challenge in recent days. This study helps to disseminate information about the importance of proper antibiotic use to control the spread of antibiotic resistance particularly in medical-surgical and critical care settings and to reinforce infection control procedures. Objectives: To determine the prevalence, distribution, and antimicrobial resistance patterns of NFGNB isolated from clinical specimens in a tertiary care hospital. Methods: This retrospective, cross-sectional study was conducted over a period of 6 months (October 2025 to March 2026) in the Department of Microbiology, Medical College, Kolkata. A total of 142 clinical isolates were analyzed. Identification was done using standard microbiological techniques and the Vitek 2 Compact system. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method as per CLSI 2023 guidelines. Results: The majority of isolates were obtained from blood samples (35%), followed by urine (26.8%). A high level of antimicrobial resistance was observed across most isolates. Notably, S. maltophilia demonstrated near-complete resistance to cotrimoxazole (95.5%) and levofloxacin (90.9%). P. aeruginosa and A. baumannii showed moderate to high resistance to commonly used antibiotics, including carbapenems and aminoglycosides. The finding of 73.9% resistance to polymyxin B among A. baumannii isolates is highly concerning and suggests extensively drug-resistant strains, whereas Serratia marcescens showed moderate resistance to carbapenems and cefoperazone–sulbactam, along with considerable resistance to colistin.A particular concerning finding was observed in S. maltophilia, which demonstrated near-complete resistance to commonly used agents including cotrimoxazole (95.5%), levofloxacin (90.9%), and minocycline (90.9%). Additionally highly resistance to polymyxin. Conclusion: The study highlights the increasing prevalence of multidrug-resistant NFGNB in clinical settings. Continuous surveillance, rational antibiotic use, and implementation of antimicrobial stewardship programs are essential to combat the growing threat of these “superbugs.” Key-words: Non-fermenting Gram-negative bacilli, antimicrobial resistance, multidrug resistance, Superbugs. Acinetobacter baumannii, Pseudomonas aeruginosa, tertiary care hospital