INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec G1K 9A9, Canada.
INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec G1K 9A9, Canada.
Chemosphere. 2018 Jul;202:549-559. doi: 10.1016/j.chemosphere.2018.03.117. Epub 2018 Mar 20.
The co-contamination of ciprofloxacin (CIP) with metal ions results in alteration of CIP mobility, antimicrobial activity and distribution/development of the antibiotic-resistance genes. In this study, the stability of five CIP-Me complexes [Me = Al(III), Co(II), Cu(II), Fe(III), Mg] was investigated in the presence of humic substances (HS) at two temperatures 18 ± 2 °C and 4 ± 1 °C for seven days period. The most stable complexes were CIP-Al, CIP-Cu, and CIP-Co with the stability constants (K) at 18 °C 35.5 ± 1.4 11.5 ± 1.5 and 11.7 ± 1.5 respectively. At lower temperature (4 °C), the stability constants decreased: 1-fold for CIP-Al, 14-fold for CIP-Co and 2-fold for CIP-Cu. The presence of humic substances decreased the stability of complexes. The chemical reactions of Fe in water at circumneutral pH resulted in stability alteration. The formation of CIP-Mg complexes at lower temperatures and in the presence of HS was limited. In ultrapure water, CIP-Me complexes exhibit higher toxicity towards Gram-negative Enterobacter aeruginosa (ranged between 0.125 and 0.5 μg/ml). However, the presence of HS reduced the antimicrobial activity of CIP-Me complexes by at least 2-fold. Gram-positive representative, Bacillus subtilis was not affected by the presence of metal ions and/or HS. The toxicity toward B. subtilis for the complexes was equal to toxicity of CIP alone (MIC = 0.25 μg/ml). This suggested the different susceptibility to CIP and its complexes.
五种 CIP-Me 配合物 [Me=Al(III)、Co(II)、Cu(II)、Fe(III)、Mg] 在 18±2°C 和 4±1°C 两种温度下，在腐殖质（HS）存在的情况下，稳定性研究为期七天。在较低温度（4°C）下，稳定常数降低：CIP-Al 降低 1 倍，CIP-Co 降低 14 倍，CIP-Cu 降低 2 倍。腐殖质的存在降低了配合物的稳定性。中性 pH 下水相中 Fe 的化学反应导致稳定性发生变化。在较低温度和 HS 存在下，形成 CIP-Mg 配合物受到限制。在超纯水中，CIP-Me 配合物对革兰氏阴性肠杆菌属铜绿假单胞菌（介于 0.125 和 0.5μg/ml 之间）表现出更高的毒性。然而，HS 的存在使 CIP-Me 配合物的抗菌活性降低至少 2 倍。革兰氏阳性代表枯草芽孢杆菌不受金属离子和/或 HS 的影响。这些配合物对 B. subtilis 的毒性与 CIP 单独的毒性（MIC=0.25μg/ml）相当。这表明对 CIP 和其配合物的不同敏感性。
