AUTHOR=Yao Lihua , Yang Lan , Ling Yuzhou , Wei Yanzhe , Shen Xiangguang , Ding Huanzhong 

TITLE=Pharmacokinetic/Pharmacodynamic Relationships of Tulathromycin Against Actinobacillus pleuropneumoniae in a Porcine Tissue Cage Infection Model

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.822432

DOI=10.3389/fvets.2022.822432

ISSN=2297-1769

ABSTRACT=<p>Tulathromycin is a semi-synthetic macrolide antibiotic that is highly effective in treating respiratory tract bacterial infections. We evaluated the <italic>in vivo</italic> antibacterial activity of tulathromycin against <italic>Actinobacillus pleuropneumoniae</italic> in piglets and determined its pharmacokinetic/pharmacodynamic (PK/PD) relationships using a tissue cage infection model. <italic>A. pleuropneumoniae</italic> (10<sup>8</sup> CFU/ml) was exposed to tulathromycin via intramuscular injection followed by a collection of cage tissue fluids at various intervals. The percentage of time the drug concentration remained above the minimum inhibitory concentration (MIC) divided by the dosing interval (%T &gt; MIC) was the best PK/PD index to describe the antibacterial efficacy of tulathromycin (<italic>R</italic><sup>2</sup> = 0.9421). The %T &gt; MIC values required to achieve 1 – log<sub>10</sub>CFU/ml reductions and bactericidal activity (3 – log<sub>10</sub>CFU/ml reduction) were 50.8 and 96.38%, respectively. These results demonstrated that maintaining %T &gt; MIC above 96.38% achieved bactericidal activity and thereby optimized the clinical dosage.</p>