Wu Tianle, Zou Huiyun, Xia Huiyu, Zhou Ziyu, Zhao Ling, Meng Min, Li Qi, Guan Yanyu, Li Xuewen
Department of environment and health, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.
Department of environment and health, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.
Ecotoxicol Environ Saf. 2023 Jun 17;262:115150. doi: 10.1016/j.ecoenv.2023.115150.
Carbapenem-resistant Enterobacteriaceae (CRE) poses major health risks worldwide. Most studies have focused on carbapenem resistance in Klebsiella pneumoniae and Escherichia coli; however, the occurrence and transmission of carbapenem-resistant Citrobacter spp. (CRCS) are poorly understood. In this study, we investigated the occurrence and potential transmission patterns of CRCS in different functional areas of an urban wastewater treatment plant (WWTP) and connecting rivers during one-year monitoring in Shandong Province, China. In total, 14 CRCS were detected in 376 environmental samples, including those from the WWTP inlet (n = 7), WWTP anaerobic tank (n = 2), and rivers (n = 5). Citrobacter braakii (n = 6) was the dominant subtype among 14 CRCS isolates, followed by Citrobacter freundii (n = 5), Citrobacter sedlakii (n = 2), and Citrobacter werkmanii (n = 1). All CRCS were resistant to imipenem, meropenem, ampicillin, amoxicillin/clavulanic acid, cefotaxime, ceftazidime, trimethoprim/sulfamethoxazole, and ciprofloxacin. Plasmid analysis showed that the bla gene was located on IncN and IncFII (Yp) plasmids, whereas the bla gene was located on IncX3 and IncN2 plasmids. Clonal transmission of CRCS harboring carbapenem genes occurred between the WWTP and connecting rivers on a temporal or spatial scale. High genomic relatedness of NDM-5-producing C. sedlakii was identified between river water and WWTP aerosol, suggesting a potential exposure risk of CRCS for workers and surrounding residents near the WWTP. Furthermore, NDM-5-producing C. sedlakii isolated from rivers was related to C. sedlakii isolated from soil and well water in different regions of China, indicating that NDM-5-producing C. sedlakii may be widespread in China. These findings indicate that rare healthcare-associated pathogens such as CRCS can contribute to widespread carbapenem production in the environment; thus, CRCS should be continuously monitored.
耐碳青霉烯类肠杆菌科细菌（CRE）在全球范围内构成重大健康风险。大多数研究集中在肺炎克雷伯菌和大肠杆菌的碳青霉烯类耐药性；然而，耐碳青霉烯类柠檬酸杆菌属（CRCS）的发生和传播情况却知之甚少。在本研究中，我们在中国山东省进行了为期一年的监测，调查了城市污水处理厂（WWTP）不同功能区域以及与之相连的河流中CRCS的发生情况和潜在传播模式。在376份环境样本中总共检测到14株CRCS，包括来自污水处理厂进水口（n = 7）、污水处理厂厌氧池（n = 2）和河流（n = 5）的样本。布氏柠檬酸杆菌（n = 6）是14株CRCS分离株中的主要亚型，其次是弗氏柠檬酸杆菌（n = 5）、塞氏柠檬酸杆菌（n = 2）和韦氏柠檬酸杆菌（n = 1）。所有CRCS均对亚胺培南、美罗培南、氨苄西林、阿莫西林/克拉维酸、头孢噻肟、头孢他啶、甲氧苄啶/磺胺甲恶唑和环丙沙星耐药。质粒分析表明，bla基因位于IncN和IncFII（Yp）质粒上，而bla基因位于IncX3和IncN2质粒上。携带碳青霉烯类基因的CRCS在时间或空间尺度上在污水处理厂和相连河流之间发生了克隆传播。在河水和污水处理厂气溶胶之间鉴定出产NDM-5的塞氏柠檬酸杆菌具有高度的基因组相关性，这表明污水处理厂附近的工人和周围居民存在接触CRCS的潜在风险。此外，从河流中分离出的产NDM-5的塞氏柠檬酸杆菌与中国不同地区土壤和井水中分离出的塞氏柠檬酸杆菌有关，这表明产NDM-5的塞氏柠檬酸杆菌可能在中国广泛存在。这些发现表明，诸如CRCS等罕见的医疗保健相关病原体可能导致环境中碳青霉烯类的广泛产生；因此，应持续监测CRCS。
