Bacterial Community Structure and Antibiotic Resistance in Hospital Wastewater in Kathmandu, Nepal

Hospital wastewater (HWW) in developing nations such as Nepal, where wastewater treatment is limited, acts as a significant reservoir for antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs), yet its contribution in disseminating antibiotic resistance is poorly understood. This study examined 19 HWW samples from nine hospitals in Kathmandu using culture-dependent and culture-independent methods to characterize bacterial phylogeny, diversity, and resistance profiles. The dominant bacterial phyla identified were Firmicutes, Bacteroidota, and Proteobacteria, with Prevotella and Acinetobacter being the most prevalent genera. Bacterial composition varied significantly across hospitals but showed no seasonal differences. The neutral community model (NCM) revealed that deterministic processes influenced bacterial community assembly. Environmental factors like temperature, pH, turbidity, and ammonia accounted for 62.7% of the variation in bacterial communities, as determined by canonical correspondence analysis (CCA) with variation partition analysis (VPA). Culture-based analysis revealed Escherichia coli and Klebsiella pneumoniae as the major extended-spectrum β-lactamase and carbapenemase producers. Specific ARGs, including bla_CTX-M, bla_TEM, bla_SHV, and aac-(6′)-Ib were significantly associated with specific taxa. Treatment at one hospital’s wastewater facility reduced ARB and potential pathogens. HWW’s role as an AMR hotspot underscores the urgent need for enhanced wastewater treatment in hospitals in Kathmandu to mitigate public health risks.