Antimicrob Agents Chemother. 2016 Oct 31. pii: AAC.01957-16. [Epub ahead of print]

Comparative In Vivo Efficacy of Tedizolid in Neutropenic versus Immunocompetent Murine Streptococcus pneumoniae Lung Infection Models.

Abdelraouf K1, Nicolau DP2,3.

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Given that tedizolid exhibits substantial lung penetration, we hypothesize that it could achieve good efficacy against Streptococcus pneumoniae lung infections. We evaluated the pharmacodynamics of tedizolid for treatment of S. pneumoniae lung infections and compared efficacy of tedizolid human-simulated epithelial lining fluid (ELF) exposures in immunocompetent and neutropenic murine lung infection models. ICR mice were rendered neutropenic via intraperitoneal cyclophosphamide injections, then inoculated intranasally with S. pneumoniae suspensions. Immunocompetent CBA/J mice were inoculated similarly. Single-daily tedizolid doses were administered 4-hr post-inoculation (0-hr). Changes in log10CFU at 24-hr compared with 0-hr controls were estimated. Area under the free-drug concentration-time curve to MIC ratios (fAUC0-24/MIC) required to achieve various efficacy endpoints against each isolate were estimated using Hill-equation. Tedizolid doses in neutropenic and immunocompetent mice that mimic the human-simulated ELF exposure were examined. Stasis, 1-log reduction and 2-log reduction were achieved at fAUC0-24/MIC of 8.96, 24.62 and 48.34 in immunocompetent mice, respectively, and 19.21, 48.29 and 103.95 in neutropenic mice, respectively. Tedizolid 40 mg/kg/day and 55 mg/kg/day in immunocompetent and neutropenic mice respectively resulted in ELF AUC0-24 comparable to that achieved in humans following 200 mg QD clinical dose. These human-simulated ELF exposures were adequate to attain >2-log reduction in bacterial burden at 24-hr in 3/4 isolates in both models and 1.58- and 0.74-log reduction with the fourth isolate in immunocompetent and neutropenic mice, respectively. Tedizolid showed potent in vivo efficacy against S. pneumoniae in both immunocompetent and neutropenic lung infection models, which support its consideration for S. pneumoniae lung infections.

Copyright © 2016, American Society for Microbiology. All Rights Reserved.

PMID: 27799200 DOI: 10.1128/AAC.01957-16

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