Spectrum and Antimicrobial Resistance of Uncommon Non‑fermenting Gram‑Negative Bacilli: A Retrospective Study from a Tertiary Care Hospital in Karachi
Background: Infections with uncommon non-fermentative Gram-negative bacilli (NFGNB) are on the rise worldwide. However, studies from developing countries mainly focus on reporting common NFGNB like Pseudomonas aeruginosa and Acinetobacter spp. Few studies report the isolation frequency and antibiotic susceptibility pattern of uncommon NFGNB from clinical samples. Objective: To determine the species distribution and antimicrobial susceptibility patterns of uncommon NFGNB from various clinical samples. Methods: This is a retrospective study of uncommon NFGNB isolated from 1st January 2013 to 31st December 2023 in the Microbiology laboratory at Liaquat National Hospital and Medical College, Karachi. Identification of uncommon NFGNB was performed through conventional methods, API 20NE, and VITEK 2 Compact. For Antibiotic susceptibility testing, Kirby-Bauer disk diffusion, E strip, and VITEK 2 Compact were used. Data analysis was performed using the computer package SPSS version 20. Results: A total of 1056 Uncommon NFGNB were isolated during the study period. The predominant species included Chryseobacterium spp 57.8% (n=611), Achromobacter xylosoxidans 12.5% (n=134), Shewanella putrifacieans 7.3% (n=78), Ralstonia Picketii 3.5% (n=37), and Brevundimonas spp 3.4% (n=36). The highest number was isolated from respiratory and blood samples of hospitalized male patients (92.8%, n=980) and from blood samples of hospitalized female patients (51.3%, n=542). The year-wise trend demonstrates a consistent isolation of NFGNB. The continued isolation of NFGNB with intrinsic resistance to Colistin underscores its rational use in hospitalized patients. Conclusion: Uncommon NFGNB are emerging pathogens and are frequently resistant to multiple antibiotics. Strict antibiotic stewardship and infection prevention measures should be implemented to preserve last-resort antibiotics.