Niang Mamadou, Reichard John F, Maier Andrew, Talaska Glenn, Ying Jun, Santo Domingo Jorge, Varughese Eunice, Boczek Laura, Huff Emma, Reponen Tiina
Department of Environmental and Public Health Sciences, College of Medicine, University of Cincinnati, Cincinnati, Ohio.
Cardno ChemRisk, Cincinnati, Ohio.
J Occup Environ Hyg. 2023 May-Jun;20(5-6):219-225. doi: 10.1080/15459624.2023.2205485. Epub 2023 May 24.
The occurrence of antibiotic-resistant bacteria (ARB) in wastewater treatment plants (WWTPs) has become an occupational and environmental concern. WWTPs are engineered systems that treat wastewater to meet public health standards before release into the environment. The residuals, as either effluent or solids, are then discharged or beneficially recycled into the environment. Since these wastes contain a diverse array of microorganisms, some of which are resistant to commonly used antibiotics, there is a potential for these organisms to spread in the environment via residual recycling and effluent discharge. Human infections with ARB are increasing, and it is not well known how the interaction between humans and the environment plays a role in this process. WWTP workers, who are on the front lines, may come into direct contact with materials containing these microbes. This study aimed to determine the number of ARB present in both air and sewage sludges in a WWTP using nonselective media supplemented with two antibiotics (ciprofloxacin and azithromycin). The densities of total heterotrophic bacteria, ciprofloxacin-resistant bacteria, and azithromycin-resistant bacteria were 7.82 × 10 - 4.7 × 10, 7.87 × 10 - 1.05 × 10, and 2.27 × 10 - 1.16 × 10 CFU/g, respectively. The prevalence [(concentration on medium with antibiotics/concentration on medium without antibiotics) × 100] of ciprofloxacin-resistant bacteria in treated sludge was twice as low as in digested sludge and approximately three times lower than in raw sludge. For azithromycin, the prevalence of resistant bacteria in treated sludge was about the same in digested and nearly twice lower than in raw sludge. Despite a marked reduction in the mean prevalence of resistant bacteria in dewatered treated sludge for both antibiotics, these differences were not significant. The highest prevalence of antibiotic resistance was observed for azithromycin. Similarly, the prevalence of airborne azithromycin-resistant bacteria inside the belt filter press room (BFPR) was nearly seven times higher than the prevalence of airborne ciprofloxacin-resistant bacteria. These concentrations of ARB were not negligible and may represent an exposure pathway for some workers in WWTPs.
污水处理厂（WWTPs）中抗生素抗性细菌（ARB）的出现已成为职业和环境方面的关注点。污水处理厂是一种工程系统，用于处理废水，使其在排放到环境之前符合公共卫生标准。然后，残余物（无论是废水还是固体）被排放或有益地循环利用到环境中。由于这些废物包含各种各样的微生物，其中一些对常用抗生素具有抗性，这些生物体有可能通过残余物循环利用和废水排放而在环境中传播。人类感染抗生素抗性细菌的情况正在增加，而人类与环境之间的相互作用在这一过程中如何发挥作用尚不清楚。处于一线的污水处理厂工人可能会直接接触含有这些微生物的物质。本研究旨在使用添加了两种抗生素（环丙沙星和阿奇霉素）的非选择性培养基，确定污水处理厂空气中和污水污泥中存在的抗生素抗性细菌数量。总异养细菌、环丙沙星抗性细菌和阿奇霉素抗性细菌的密度分别为7.82×10 - 4.7×10、7.87×10 - 1.05×10和2.27×10 - 1.16×10 CFU/g。处理后污泥中环丙沙星抗性细菌的流行率[（含抗生素培养基上的浓度/不含抗生素培养基上的浓度）×100]比消化污泥中的低两倍，比原污泥中的低约三倍。对于阿奇霉素，处理后污泥中抗性细菌的流行率在消化污泥中大致相同，比原污泥中低近两倍。尽管两种抗生素在脱水处理后污泥中抗性细菌的平均流行率均显著降低，但这些差异并不显著。观察到阿奇霉素的抗生素抗性流行率最高。同样，带式压滤机房（BFPR）内空气中阿奇霉素抗性细菌的流行率比空气中环丙沙星抗性细菌的流行率高近七倍。这些抗生素抗性细菌的浓度不可忽视，可能代表了污水处理厂一些工人的接触途径。
