Influence of a Non-Hospital Medical Care Facility on Antimicrobial Resistance in Wastewater

The global widespread use of antimicrobials and accompanying increase in resistant bacterial strains is of major public health concern. Wastewater systems and wastewater treatment plants are considered a niche for antibiotic resistance genes (ARGs), with diverse microbial communities facilitating ARG transfer via mobile genetic element (MGE). In contrast to hospital sewage, wastewater from other health care facilities is still poorly investigated. At the instance of a nursing home located in south-west Germany, in the present study, shotgun metagenomics was used to investigate the impact on wastewater of samples collected up- and down-stream in different seasons. Microbial composition, ARGs and MGEs were analyzed using different annotation approaches with various databases, including Antibiotic Resistance Ontologies (ARO), integrons and plasmids. Our analysis identified seasonal differences in microbial communities and abundance of ARG and MGE between samples from different seasons. However, no obvious differences were detected between up- and downstream samples. The results suggest that, in contrast to hospitals, sewage from the nursing home does not have a major impact on ARG or MGE in wastewater, presumably due to much less intense antimicrobial usage. Possible limitations of metagenomic studies using high-throughput sequencing for detection of genes that seemingly confer antibiotic resistance are discussed.

全球范围内抗菌药物的广泛使用以及随之而来的耐药菌株增多，已成为重大公共卫生关切问题。废水系统与污水处理厂被认为是抗生素抗性基因（antibiotic resistance genes, ARGs）的富集生境，多样的微生物群落可通过移动遗传元件（mobile genetic element, MGE）促进ARGs的水平转移。与医院污水不同，其他医疗机构产生的废水相关研究仍较为匮乏。本研究以德国西南部一家养老院为研究对象，采用鸟枪法宏基因组学（shotgun metagenomics）技术，对不同季节采集的污水处理厂上下游废水样本展开分析，以探究该养老院废水对周边废水系统的影响。本研究采用多种注释方法结合多类数据库（包括抗生素抗性本体（Antibiotic Resistance Ontologies, ARO）、整合子与质粒数据库），对样本的微生物群落组成、ARGs及MGEs进行分析。分析结果显示，不同季节采集的样本在微生物群落组成以及ARGs与MGEs的丰度上均存在季节性差异，但未在上下游样本之间检测到显著差异。研究结果表明，与医院污水不同，该养老院产生的废水并不会对废水中的ARGs与MGEs丰度造成显著影响，推测原因是其抗菌药物使用强度远低于医院。本文还讨论了采用高通量测序（high-throughput sequencing）的宏基因组学研究在检测潜在耐药基因时可能存在的局限性。