# Survey of Antimicrobial-Resistant Bacteria Isolated from Rivers in Japan, Indonesia and Nepal

## TL;DR

This study examines antimicrobial-resistant bacteria in rivers from Japan, Indonesia, and Nepal, finding significant differences in bacterial communities and resistance levels.

## Contribution

The study provides a comparative analysis of antimicrobial resistance in river systems across three Asian countries using selective culture-based sequencing.

## Key findings

- Nepal showed the highest abundance of antimicrobial resistance genes, mainly β-lactam resistance genes.
- Bacterial communities varied significantly between sampling sites across the three countries (p < 0.001).
- Pseudomonas, Stenotrophomonas, and Acinetobacter were common in Japan and Indonesia, while Klebsiella dominated in Nepal.

## Abstract

The threat of antimicrobial resistance in aquatic environments, particularly riverine systems, is escalating, in part due to effluents discharged from healthcare facilities. This issue has been recognized not only in Japan but also in other Asian countries such as Indonesia and Nepal. Nevertheless, existing research remains limited, prompting an investigation into the prevalence of antimicrobial-resistant bacteria in the upstream and downstream sites of environmental rivers. In 2024, six samples were collected from three rivers in Hyogo Prefecture, Japan; five samples from five river sites in Indonesia; and three samples from downstream sites of rivers in Kathmandu, Nepal. These samples were subjected to selective culture–based Next Generation Sequencing and resistome analyses, based exclusively on the selective culture of bacteria propagated on CHROMagar ESBL plates. In Japan and Indonesia, Pseudomonas, Stenotrophomonas and Acinetobacter were frequently detected, whereas Klebsiella was overwhelmingly predominant in Nepal. Significant differences in the similarity of bacterial community composition among sampling sites across the three countries were observed (p < 0.001). Notably, Nepal exhibited the highest abundance level of antimicrobial resistance genes among the three countries, largely consisting of β-lactam resistance genes. In conclusion, these analyses elucidated substantial differences in bacterial community composition and degrees of environmental contamination.