Environmental Dissemination of Antimicrobial Resistance: A Resistome-Based Comparison of Hospital and Community Wastewater Sources

Abstract

Background/Objectives: Comparative analysis of antimicrobial resistomes in hospital and community wastewater can provide valuable insights into the diversity and distribution of antimicrobial resistance genes (ARGs), contributing to the advancement of the One Health approach. This study aimed to characterize and compare the resistome profiles of wastewater sources from a hospital and community. Methods: Longitudinal metagenomic analysis was conducted on wastewater samples collected from the National Center for Global Health and Medicine (hospital) and a shopping mall (community) in Tokyo, Japan, between December 2019 and September 2023. ARG abundance was quantified using reads per kilobase per million mapped reads (RPKM) values, and comparative analyses were performed to identify the significantly enriched ARGs in the two sources. Results: A total of 46 monthly wastewater samples from the hospital yielded 825 unique ARGs, with a mean RPKM of 2.5 across all detected genes. In contrast, 333 ARGs were identified in the three shopping mall wastewater samples, with a mean RPKM of 2.1. Among the ARGs significantly enriched in the hospital samples, 23, including genes conferring resistance to aminoglycosides (nine groups) and β-lactam antibiotics (eight groups), exhibited significantly high RPKM values. No ARGs were found to be significantly enriched in the community wastewater samples. Conclusions: This study highlights the higher diversity and abundance of ARGs, particularly those conferring resistance to aminoglycosides and β-lactam antibiotics including carbapenems, in hospital wastewater than in community wastewater. These findings underscore the importance of continuous resistome monitoring of hospital wastewater as part of the integrated One Health surveillance strategy.

Keywords: antimicrobial resistance (AMR); antimicrobial stewardship; community; hospital; wastewater.

Figure 1

Volcano plot of the ratios of the mean reads per kilobase per million mapped reads (RPKM) values between the hospital and community wastewater samples from December 2019 to September 2023. Significantly higher RPKM (−log₁₀ p-value > 2.0 and |log₁₀ FC| > 0.3) values in the hospital samples were highlighted with orange color with ARG name, while blue color indicated non-significance.

Figure 2

(a) Temporal variations in the concentration ratios and (b) distribution of the concentration ratios of clarithromycin and levofloxacin from June 2020 to June 2023. Different characters within the violin plot (a and b) indicate significant differences between groups. (p < 0.05).