School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, United States.
Rollins School of Public Health, Emory University, Atlanta, GA, United States.
Environ Res. 2021 Mar;194:110730. doi: 10.1016/j.envres.2021.110730. Epub 2021 Jan 11.
Antibiotic resistance poses a major global health threat. Understanding emergence and dissemination of antibiotic resistance in environmental media is critical to the design of control strategies. Because antibiotic resistance genes (ARGs) may be aerosolized from contaminated point sources and disseminated more widely in localized environments, we assessed ARGs in aerosols in urban La Paz, Bolivia, where wastewater flows in engineered surface water channels through the densely populated urban core. We quantified key ARGs and a mobile integron (MI) via ddPCR and E. coli spp. as a fecal indicator by culture over two years during both the rainy and dry seasons in sites near wastewater flows. ARG targets represented major antibiotic groups-tetracyclines (tetA), fluoroquinolines (qnrB), and beta-lactams (bla)-and an MI (intI1) represented the potential for mobility of genetic material. Most air samples (82%) had detectable targets above the experimentally determined LOD: most commonly bla and intI1 (68% and 47% respectively) followed by tetA and qnrB (17% and 11% respectively). ARG and MI densities in positive air samples ranged from 1.3 × 10 to 6.6 × 10 gene copies/m air. Additionally, we detected culturable E. coli in the air (52% of samples <1 km from impacted surface waters) with an average density of 11 CFU/m in positive samples. We observed decreasing density of bla with increasing distance up to 150 m from impacted surface waters. To our knowledge this is the first study conducting absolute quantification and a spatial analysis of ARGs and MIs in ambient urban air of a city with contaminated surface waters. Environments in close proximity to urban wastewater flows in this setting may experience locally elevated concentrations of ARGs, a possible concern for the emergence and dissemination of antimicrobial resistance in cities with poor sanitation.
抗生素耐药性对全球健康构成重大威胁。了解环境介质中抗生素耐药性的出现和传播对于控制策略的设计至关重要。由于抗生素耐药基因（ARGs）可能从受污染的点源气溶胶化，并在局部环境中更广泛地传播，因此我们评估了玻利维亚拉巴斯市城市环境中的气溶胶中的 ARGs。该市的污水在经过工程化的地表水渠道流经人口稠密的城市核心区。在两年的时间里，我们在雨季和旱季对靠近污水流的地点进行了培养，以量化关键的 ARGs 和移动整合子（MI）（通过 ddPCR）和大肠杆菌 spp.（作为粪便指示物）。ARG 靶标代表了主要的抗生素类别-四环素（tetA），氟喹诺酮（qnrB）和β-内酰胺（bla）-以及一个 MI（intI1）代表遗传物质移动的潜力。大多数空气样本（82％）的检测到的目标高于实验确定的 LOD：最常见的是 bla 和 intI1（分别为 68％和 47％），其次是 tetA 和 qnrB（分别为 17％和 11％）。阳性空气样本中的 ARG 和 MI 密度范围为 1.3×10 至 6.6×10 基因拷贝/m3。此外，我们在空气中检测到可培养的大肠杆菌（距离受影响地表水 1 公里以内的样本的 52％），阳性样本的平均密度为 11 CFU/m。我们观察到，随着与受影响地表水的距离的增加，bla 的密度逐渐降低，直到 150 米。据我们所知，这是第一项在受污染地表水的城市环境中对环境空气中的 ARGs 和 MIs 进行绝对定量和空间分析的研究。在这种情况下，与城市污水流量接近的环境可能会经历局部升高的 ARG 浓度，这可能是对卫生条件差的城市中出现和传播抗微生物耐药性的关注。
