Increased Antimicrobial Activity of Colistin in Combination With Gamithromycin Against Pasteurella multocida in a Neutropenic Murine Lung Infection Model

Frontiers in Microbiology

Liqin Wu¹  Tianan Xiao¹  Junwen Zhou²  Hao Lin²  Mengjuan Xie²  Huanzhong Ding²  Yanqin Li²  Binghu Fang² 

[1] Guangdong Center for Agricultural Products Quality and Safety, Guangzhou, China;Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China;National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China;

关键词: colistin;    gamithromycin;    combination;    therapy;    Pasteurella multocida;   

DOI  :  10.3389/fmicb.2020.511356

来源: DOAJ

【 摘 要 】

We investigate the antimicrobial activity of combined colistin and gamithromycin against nine Pasteurella multocida strains by testing in vitro susceptibility. Two high-colistin minimal inhibitory concentration (MIC) isolates (D18 and T5) and one low-colistin MIC isolate (WJ11) were used in time-kill tests and therapeutic effect experiments using a neutropenic murine pneumonia model over 24 h. Pharmacokinetics (PK) in plasma was calculated along with pharmacodynamics (PD) to determine the PK/PD index. Synergy between colistin and gamithromycin was observed using high-colistin MIC isolates, equating to a 128- or 256-fold and 4- or 8-fold reduction in colistin and gamithromycin concentration, respectively. Interestingly, no synergistic effect of the combination on low-colistin MIC isolates was observed. However, regardless of the MIC difference among isolates, each drug tended to reach the same concentration in all isolates subjected to combined treatments, which was verified by the time-kill tests presenting similar rates and extent of killing for isolates D18, T5, and WJ11. The AUC(0–24 h)/MIC index was used to evaluate the relationship between PK and PD, and the correlation was >0.89. The relevant gamithromycin doses for combined therapy were determined, and the value decreased from 6- to 35-fold compared with monotherapy. Combined colistin and gamithromycin therapy provides a more potent therapeutic regimen than monotherapy against P. multocida strains.

【 授权许可】

Unknown