Zhang Longfei, Kang Zheng, Yao Lihua, Gu Xiaoyan, Huang Zilong, Cai Qinren, Shen Xiangguang, Ding Huanzhong
Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
Technical Center for Inspection and Quarantine, Zhuhai Entry-Exit Inspection and Quarantine Bureau, Zhuhai, China.
Front Microbiol. 2018 Oct 10;9:2445. doi: 10.3389/fmicb.2018.02445. eCollection 2018.
To evaluate the relationship between pharmacokinetic/pharmacodynamic (PK/PD) parameters and changes in susceptibility and resistance frequency of CVCC 259, a piglet tissue cage (TC) infection model was established. After populations maintained at 10 CFU/mL in TCs, piglets were treated with various doses of danofloxacin once daily for 5 consecutive days by intramuscular injection. Both the concentrations of danofloxacin and the population of vial cells were determined. Changes in susceptibility and resistance frequency were monitored. Polymerase chain reaction (PCR) amplification of quinolone resistance-determining regions (QRDRs) and DNA sequencing were performed to identify point mutations in , , , and genes. Furthermore, the susceptibility of mutants to danofloxacin and enrofloxacin was determined in the presence or absence of reserpine to assess whether the mutants were caused by efflux pumps. The MICs and resistant frequency of both increased when danofloxacin concentrations fluctuated between MIC (0.05 μg/mL) and MPC (mutant prevention concentration, 0.4 μg/mL). As for PK/PD parameters, the resistant mutants were selected and enriched when AUC/MIC ranged from 34.68 to 148.65 h or AUC/MPC ranged from 4.33 to 18.58 h. Substitutions of Ser-83→Tyr or Ser-83→Phe in and Lys-53→Glu in were observed. The susceptibility of mutants obtained via danofloxacin treatment at 1.25 and 2.5 mg/kg were less affected by reserpine. These results demonstrate that maintaining the value of AUC/MPC above 18.58 h may produce a desirable antibacterial effect and protect against resistance to danofloxacin.
为评估药代动力学/药效学（PK/PD）参数与CVCC 259的敏感性及耐药频率变化之间的关系，建立了仔猪组织笼（TC）感染模型。在TC中菌量维持在10 CFU/mL后，仔猪每天通过肌肉注射给予不同剂量的达氟沙星，连续5天。测定达氟沙星浓度和菌液细胞数量。监测敏感性和耐药频率的变化。进行喹诺酮耐药决定区（QRDRs）的聚合酶链反应（PCR）扩增和DNA测序，以鉴定gyrA、gyrB、parC和parE基因中的点突变。此外，在有或没有利血平存在的情况下，测定突变体对达氟沙星和恩诺沙星的敏感性，以评估突变体是否由外排泵引起。当达氟沙星浓度在MIC（0.05μg/mL）和MPC（突变预防浓度，0.4μg/mL）之间波动时，gyrA和parC的MIC和耐药频率均增加。至于PK/PD参数，当AUC/MIC范围为34.68至148.65 h或AUC/MPC范围为4.33至18.58 h时，耐药突变体被选择并富集。观察到gyrA中Ser-83→Tyr或Ser-83→Phe以及parC中Lys-53→Glu的替换。通过1.25和2.5 mg/kg达氟沙星处理获得的突变体的敏感性受利血平的影响较小。这些结果表明，将AUC/MPC值维持在18.58 h以上可能产生理想的抗菌效果，并防止对达氟沙星产生耐药性。
