Isolation, Identification, and Antibiogram of Colistin-resistant Acinetobacter baumannii from Rivers in and around Kathmandu Valley

Background: Acinetobacter baumannii, an opportunistic Gram-negative pathogen, poses an escalating threat in clinical settings due to the rise of multidrug-resistant infections. Despite its clinical significance, there exists a considerable gap in understanding its environmental dissemination. Aims and Objectives: The primary objective is to examine the distribution of A. baumannii and its antibiotic resistance in river ecosystems. Specifically, we aim to identify strains resistant to Colistin, a last-resort antibiotic, and elucidate the susceptibility patterns to other antibiotics. Materials and Methods: Water samples from 10 rivers were collected and subjected to analysis using Leeds Acinetobacter Agar Base and a series of biochemical tests. Antibiotic susceptibility testing, focusing on Colistin resistance, was performed using standard procedures. Results: Out of the 284 isolated strains, 14 (4.9%) exhibited resistance to Colistin, while demonstrating varying susceptibility patterns to other antibiotics. Notably, Gentamycin showed effectiveness against resistant strains (14.28%), while Ceftazidime resistance was complete. Colistin-sensitive strains displayed high susceptibility to Ciprofloxacin (84.44%) and lower susceptibility to Chloramphenicol (53.33%). Carbapenem susceptibility was observed across all isolates. Conclusion: The study underscores a concerning environmental presence of multidrug-resistant A. baumannii in rivers around Kathmandu Valley, with Sundarijal being the exception. The findings emphasize the necessity of scrutinizing environmental reservoirs for pathogen spread, advocating for heightened awareness of potential health implications beyond clinical settings. Urgent attention is needed to comprehend and counteract the emergence and dissemination of antibiotic resistance, necessitating comprehensive strategies and continued surveillance