<![CDATA[Introduction: Antimicrobial resistance (AMR) has been recognized as an emerging concern in rivers that receive domestic wastewater, serving as reservoirs for antibiotic-resistant bacteria. As home to 15 million people, the Brantas River has limited data on environmental AMR patterns. This study aimed to describe the link between community practices and AMR patterns in the upper Brantas. Methods: This cross-sectional study assessed resistance patterns in the upper Brantas River by comparing two sites based on population density differences. Fifty respondents from households adjacent to the river were interviewed regarding sanitation practices and antibiotic use. Water samples were analyzed for domestic wastewater. Sixteen coliform isolates were tested for antimicrobial resistance using six antibiotics from different classes. Resistance was quantified using the multiple antibiotic resistance index (MARI) and compared between sites. Results and Discussion: Unlike the upstream community, the mid-reach area had limited sanitation facilities, resulting in river-based sanitation as a common practice. Both sites exhibited a similar pattern of antibiotic use, with > 70% of respondents engaged in inappropriate consumption. Although antibiotic residues were not detected at either site, coliform and resistance loads were higher in the mid-reach. Overall, both sites demonstrated MARI values > 0.2, indicating sustained selective pressure for resistance. Conclusion: Elevated MARI values were observed at both sites without detectable antibiotic residues. Resistance levels were higher at the mid-reach site, where sanitation access was limited and inappropriate antibiotic use was common. These findings underline the position of considering sanitation conditions and antibiotic use practices in environmental health surveillance.]]>
