Prevalence and Antibiogram of Non-Fermenting Gram-Negative Bacilli Isolates Obtained from Various Clinical Samples at A Tertiary Care Hospital

Background: Non-fermenting Gram-negative bacilli (NFGNB) are increasingly recognized as important healthcare-associated pathogens because of their ability to survive in hospital environments and develop resistance to multiple antimicrobial agents. This study aimed to determine the prevalence of NFGNB isolated from various clinical specimens and assess their antimicrobial susceptibility pattern at a tertiary care hospital. Material and Methods: A descriptive study was conducted in the Department of Microbiology, GMERS Medical College and attached General Hospital, Gandhinagar, Gujarat, from January to December 2024. A total of 8,060 clinical specimens were processed using standard microbiological methods. NFGNB were identified by conventional biochemical tests, and antimicrobial susceptibility testing was performed according to CLSI 2024 guidelines. Results: Of 8,060 specimens, 1,900 (23.57%) showed bacterial growth, and 285 NFGNB were isolated, giving an overall prevalence of 3.53%. Pseudomonas aeruginosa (58.24%) was the predominant isolate, followed by Acinetobacter baumannii (31.92%). Most isolates were from hospitalized patients (82.45%), and pus-related specimens were the commonest source (60.70%). P. aeruginosa showed high susceptibility to piperacillin-tazobactam and aztreonam (89.75% each) and cefepime (89.15%). In contrast, A. baumannii showed considerably lower susceptibility to most antibiotics, including imipenem (21.97%) and meropenem (25.27%). Conclusion: NFGNB are important healthcare-associated pathogens, with P. aeruginosa and A. baumannii being the predominant isolates. The high antimicrobial resistance observed in A. baumannii highlights the need for regular surveillance of local antibiograms, rational antibiotic use, antimicrobial stewardship and effective infection-control practices.

Keywords: Non-fermenting Gram-negative bacilli; Pseudomonas aeruginosa; Acinetobacter baumannii; antimicrobial susceptibility; antibiogram; antimicrobial resistance; healthcare-associated infections.