Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institut, Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institut, Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany; University Hospital Heidelberg, Department of Clinical Pharmacology and Pharmacoepidemiology, Im Neuenheimer Feld 410, Heidelberg, Germany.
Sci Total Environ. 2019 Feb 15;651(Pt 1):1605-1612. doi: 10.1016/j.scitotenv.2018.09.248. Epub 2018 Sep 20.
β‑Lactam antibiotics are among the most widely used antibiotics in human medicine and their effects on the aquatic environment - concerning bacterial resistance - are controversially discussed. This study focused on the photolysis of the four β‑lactam antibiotics - amoxicillin, ampicillin, penicillin V and piperacillin - under simulated environmental conditions. It was observed that all investigated β‑lactam antibiotics are photolytically degradable by simulated sunlight (1 kW/m) with half-lives between 3.2 and 7.0 h. Structure elucidation of transformation products performed with liquid chromatography coupled to high resolution mass spectrometry showed that the hydrolysis of the β‑lactam ring is the primary transformation reaction, followed by the elimination of carboxylic and dimethyl thiazolidine carboxylic acid. Growth inhibition tests on Bacillus subtilis showed the loss of bactericide activity of irradiated solutions of amoxicillin, ampicillin and piperacillin, suggesting the transformation of the β‑lactam ring is responsible for the antibiotic effect. In contrast, the solutions of penicillin V did not show any decline of the antibacterial activity after photolytic degradation, probably due to the formation of still active epimers.
β-内酰胺类抗生素是人类医学中应用最广泛的抗生素之一，其对水生环境（涉及细菌耐药性）的影响存在争议。本研究聚焦于四种β-内酰胺类抗生素（阿莫西林、氨苄西林、青霉素 V 和哌拉西林）在模拟环境条件下的光解。结果表明，所有研究的β-内酰胺类抗生素在模拟阳光（1kW/m）下均具有光解降解性，半衰期在 3.2 到 7.0 小时之间。通过液相色谱与高分辨率质谱联用进行的转化产物结构阐明表明，β-内酰胺环的水解是主要的转化反应，随后是羧酸和二甲基噻唑烷羧酸的消除。枯草芽孢杆菌的生长抑制试验表明，经辐照的阿莫西林、氨苄西林和哌拉西林溶液的杀菌活性丧失，这表明β-内酰胺环的转化是抗生素作用的原因。相比之下，青霉素 V 溶液在光解降解后其抗菌活性并没有下降，这可能是由于形成了仍具有活性的差向异构体。
