4种氨基糖苷类抗生素联用氯霉素对青海弧菌Q67 联合毒性作用及机制

近年来，氨基糖苷类(Aminoglycoside, AG)抗生素与氯霉素(Chloramphenicol, CHL)联用产生增毒作用而引起的死亡事件屡见不鲜。以4种AG抗生素：盐酸大观霉素(SPC)、硫酸小诺霉素(MCR)、硫酸丁胺卡那霉素(AMK)、妥布霉素(TOB)和氯霉素(CHL)为研究对象，选择青海弧菌(Vibrio qinghaiensis sp.-Q67，Q67)作为指示生物，采用直线均分法设计二元混合物，采用最小二乘法拟合浓度-效应数据，运用浓度加和(CA)模型对药物间的毒性相互作用进行评估，并同步分析抗生素联合毒性作用机理。结果表明：在暴露时间为12 h时，以半数浓度效应(EC₅₀)的负对数pEC₅₀值为毒性指标，5种抗生素的毒性大小顺序为TOB > CHL > MCR > AMK >SPC；4种AG抗生素与CHL的二元混合物的联合毒性作用特点因混合组分的不同而不同，Q67在二元混合物的EC₅₀浓度水平、暴露12 h后，细胞形态均未发生显著变化，而在单个抗生素的EC₅₀浓度、暴露12 h后，细胞明显受损，但损伤程度不同；大部分受混合物作用的Q67的发光相关物质含量在EC₅₀效应下均低于空白组，抗生素及其混合物的作用机制很可能是通过干扰发光菌体内蛋白质合成，进而导致细菌代谢紊乱，最终致其死亡。

Toxicity and mechanism of four aminoglycoside antibiotics combined with chloramphenicol towards Vibrio qinghaiensis sp. -Q67

In recent years, there have been a number of deaths caused by the synergistic effects of aminoglycoside (AG) antibiotics in combination with chloramphenicol (CHL). Therefore, combined toxicities of four AG antibiotics: spectinomycin hydrochloride (SPC), succinomycin sulfate (MCR), amikacin sulfate (AMK), tobramycin (TOB) and CHL towards a freshwater organism Vibrio qinghaiensis sp.-Q67 (Q67) were investigated by the time-dependent toxicity microplate analysis method. Thereon, a direct equipartition ray design method was used to design binary mixtures with different concentration ratios. Concentration addition (CA) model was used to analyze toxicity interaction within mixtures. The results showed that: when the exposure time is 12 h, the negative logarithmic pEC₅₀ value of EC₅₀ (median effect concentration) being as toxicity index, the toxicity order of the five antibiotics is TOB>CHL>MCR>AMK>SPC. The combined toxicity characteristics of binary mixture of four AG antibiotics and CHL vary with the composites of the mixture. Generally, most of the cells of Q67 do not change significantly after exposure for 12 h to EC₅₀ of binary mixture, but the damage degree of cells is different after exposure for 12 h to EC₅₀ of single antibiotics. The content of luminescence-related substances in most of the Q67 treated by the mixture with EC₅₀ was lower than that in the control. Combined with the results of SEM (scanning electron microscopy), it was concluded that the mechanism of antibiotics and their mixtures may be through the interference of protein synthesis in luminescent bacteria, leading to bacterial metabolic disorders and even death.