基于体内PK/PD同歩模型的达氟沙星对鸡毒支原体、大肠杆菌混合感染防耐药突变研究

Co-infection of bacteria and mycoplasma is very commonplace, therefore, it is crucial to explore the in vivo Pharmacokinetic/Pharmacodynamic (PK/PD) Profiles and mutant selection window (MSW) of antibacterials against multiple pathogens based on co-infection model for promoting the eradication of bacteria and reducing drug resistance. Mycoplasma gallisepticum (MG) usually co-infected chickens with Escherichia coli (E. coli), which causes significant losses. Danofloxacin plays a key role in treating the infection. Our previous study has established the MG S6 - E. coli O78 co-infection model and demonstrated that the pathological status due to the infection influences the PK profile of danofloxacin. However, the impact on PK/PD profiles and MSW still need further study. Our study aims to: (1) establish the in vivo PK/PD model of danofloxacin against MG and E. coli respectively in the MG S6 - E. coli O78 co-infection chickens, (2) clarify the MSW of danofloxacin which would affect the susceptibility of MG and E. coli against danofloxacin, (3) derive a rational approach of danofloxacin with respect to bacteriological and resistance outcomes using the Monte Carlo Analysis. The investigation results provide a solid foundation for the usage of danofloxacin against MG-E. coli co-infection and controlling resistance.

临床疾病常由多个病原混合感染引发，以疾病为导向，研究抗菌药对多个病原的体内PK/PD同步关系及突变选择窗（MSW），可更好地优化药效并减少耐药性的产生。达氟沙星是治疗鸡毒支原体（MG）、大肠杆菌（E. coli）混合感染的常用药物。前期研究发现，MG- E. coli混合感染雏鸡会改变达氟沙星的药动学特征，但是对其PK/PD同步模型及MSW的影响尚不清楚。本研究内容包括：1）在MG- E. coli混合感染雏鸡中，建立达氟沙星对MG、E. coli的体内PK/PD同步模型；2）以PK/PD结果为基础，通过药板筛选法及探针荧光定量PCR法确定达氟沙星对两种病原的体内MSW；3）利用蒙特卡罗分析整合药动学及病原敏感性差异，模拟PK/PD参数分布，以最佳PK/PD参数值为靶标，避开MSW，推导达氟沙星给药方案。本研究从多角度优化达氟沙星作用，为指导合理使用达氟沙星，减少耐药性产生与传播奠定基础。

达氟沙星是治疗大肠杆菌（E.coli）、沙门菌、鸡毒支原体（MG）等感染的常用药物，且临床上常常出现混合感染的情况，如E.coli-MG混合感染雏鸡造成禽慢性呼吸道综合征。构建达氟沙星对这些病原的体内PK/PD同步模型，阐明最佳PK/PD参数值，并优化达氟沙星对混合感染的给药方案，为指导合理使用达氟沙星提供了依据。本项目成功构建了MG-E.coli混合感染雏鸡模型及鼠伤寒沙门菌感染兔模型，并在此基础上研究了达氟沙星的药动学，体内药效学特征。发现在1~30 mg/kgb.w.剂量范围内，达氟沙星在两种感染动物体内的吸收比例和范围都较稳定，药代动力学参数 AUC0-24，Cmax与给药剂量呈线性关系。体内药效学研究中，随着给药剂量的增加，体内杀菌效果随之增强。PK/PD拟合结果显示，达氟沙星PK/PD参数AUC0-24/MIC与体内药物的抗菌效应拟合良好。当AUC0-24h/MIC分别为618.56和623.72时，可以使鸡肝脏和肺脏大肠杆菌减少3Log10 cfu/mL。对于鸡毒支原体当AUC0-24h/MIC分别为462.45和2452.18时，可以达到抑菌和杀菌的效果。而对于鼠伤寒沙门菌感染兔中，达氟沙星在血液、肝脏、脾脏、肺脏中达到杀菌作用需达到的AUC0-24h/MIC值分别为60.65、177.14、108.32和114.33。故对于鼠伤寒沙门菌，选择的靶器官不同会影响PK/PD最佳参数值，进而影响给药方案的确定。对于MG-E.coli混合感染疾病的治疗，给药剂量分别是7和38mg/kg b.w.，一天一次，连续给药三天能够对两种病原达到抑菌和杀菌的效果。本项目研究结果为指导合理使用达氟沙星，减少耐药性产生与传播奠定基础。