Between August 2018 and June 2019, a river system in Germany that supplies a drinking water reservoir and is subject to the discharge from two sewage treatment plants was monitored for antibiotic residues via liquid chromatography–tandem mass spectrometry, antibiotic resistance genes (including bla_NDM, bla_VIM, bla_OXA-48, bla_KPC, bla_GIM, bla_SME, bla_IMI, bla_IMP, bla_SPM, bla_SIM, bla_OXA-23, bla_OXA-24, bla_OXA-51, bla_OXA-58, mcr) via qualitative real-time PCR and antibiotic-resistant bacteria [belonging to the ESKAPE-group (Enterococcus faecium, Staphyhlococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter ssp.; with resistance against Carbapenemases, Cephalosporines and Colistin) and Escherichia coli] based on cultivation methods followed by a characterization via MALDI-TOF MS and susceptibility testing applying microdilution.

Residues of macrolide antibiotics such as clarithromycin (up to 0.60 μg/L) and residues of sulfamethoxazole (up to 0.40 μg/L) and trimethoprim (up to 0.39 μg/L) were detected downstream of the sewage treatment plants. In addition, no antibiotic residues were detected upstream the respective sewage treatment plants, except for anhydroerythromycin (n = 1, <LOQ). In total, bla_OXA-58 was found in 6, and mcr in one water sample throughout the whole sample period. No MRSA, extensively drug-resistant or pan-resistant bacteria, according to Magiorakos et al. (2011), could be isolated. In contrast, multidrug-resistant bacteria, especially E. coli and Enterococcus faecium were found.

In conclusion, sewage treatment plant effluents are point sources for antibiotic residues (p = 0.0000 and p = 0.0001) and antibiotic-resistant bacteria (p = 0.0021 and p = 0.0060) since their concentrations increased significantly after the discharge of treated wastewater into the investigated rivers. In this specific catchment area, which lacked clinical, hospitals, and intensive livestock farming, no significant bacterial or analyzed chemical (antibiotic residues) influences of the sewage treatment plants were observed in the river downstream of the drinking water reservoir during the study. Furthermore, no increased selection pressure could be expected as no measured antibiotic residues exceeded the predicted no effect concentration for antibiotic resistance selection, according to Bengtsson-Palme and Larsson (2016).

在2018年8月至2019年6月之间，德国的一个供水系统供水并经两个污水处理厂排放后，通过液相色谱-串联质谱，抗生素抗性基因（包括bla _NDM ， bla _VIM ，bla _OXA-48 ，bla _KPC ，bla _GIM ，bla _SME ，bla _IMI ，bla _IMP ，bla _SPM ，bla _SIM ，bla _OXA-23，bla _OXA-24 ，bla _OXA-51 ，bla _OXA-58 ，mcr）通过定性实时PCR和抗药性细菌[属于ESKAPE组（粪便肠球菌，金黄色葡萄球菌，肺炎克雷伯菌，鲍曼不动杆菌，铜绿假单胞菌和肠杆菌属；对碳青霉菌和大肠杆菌的耐药性）大肠杆菌]基于培养方法，然后通过MALDI-TOF MS进行表征，并使用微量稀释法进行药敏试验。

在污水处理厂下游检测到大环内酯类抗生素的残留，如克拉霉素（最高0.60μg/ L），磺胺甲恶唑（最高0.40μg/ L）和甲氧苄啶（最高0.39μg/ L）。此外，除脱水红霉素（n = 1，<LOQ）外，在各自的污水处理厂上游均未检测到抗生素残留。整个样本期间，总共在6个水中发现了bla _OXA-58，在一个水样本中发现了mcr。根据Magiorakos等人的研究，没有MRSA，即具有广泛耐药性或泛抗性的细菌。（2011），可能是孤立的。相反，发现了具有多重耐药性的细菌，尤其是大肠杆菌和粪肠球菌。

总之，污水处理厂的废水是抗生素残留（p = 0.0000和p = 0.0001）和抗药性细菌（p = 0.0021和p = 0.0060）的点源，因为它们的浓度在将处理过的废水排放到被调查的废水中后显着增加。河流。在该缺乏临床，医院和集约化畜牧业的特定集水区，在研究期间，在饮用水水库下游的河流中未观察到污水处理厂的明显细菌或分析化学（抗生素残留）影响。此外，根据Bengtsson-Palme和Larsson（2016）的研究，由于没有测得的抗生素残留超过预期的抗生素抗性选择浓度，因此无法预期选择压力会增加。