Bone penetration of linezolid in osteoarticular tuberculosis patients of China

•Linezolid in bone of osteoarticular tuberculosis patient was detected, which had rarely been reported.•A ratio between blood/bone linezolid concentrations of 0.42 was identified.•Samples collected 200–510mins after dosing had very good linear relationship between bone and plasma concentrations (r=0.9323).•Bone linezolid concentration prediction could be accurately performed with known plasma concentration during 200–510mins after dosing. Linezolid presents strong antimicrobial activity against multidrug-resistant (MDR) pulmonary tuberculosis (TB), but its application in osteoarticular tuberculosis treatment remains understudied. Our objective was to analyze the bone penetration efficiency of linezolid in osteoarticular TB patients. Osteoarticular TB patients, treated with 600 mg q 24 h linezolid-containing regimens and undergoing surgery, were prospectively and consecutively enrolled. One dose linezolid was administered before surgery. Blood and bone samples were collected simultaneously during operation, and their linezolid concentrations were then detected using high-performance liquid chromatography-tandem mass spectrometry. Pus samples were subjected to mycobacterial culture and GeneXpert MTB/RIF assay. The minimum inhibition concentrations (MICs) and drug susceptibility testing were performed with the recovered isolates. A total of 36 eligible osteoarticular TB patients were enrolled, including five MDR/rifampicin-resistant cases. All the 12 recovered isolates had MICs ≤0.5 μg/mL for linezolid. Mean concentrations in plasma, collected 100−510 min after the preoperative dosing, were 10.43 ± 4.83 μg/mL (range 3.29−22.26 μg/mL), and median concentrations in bone were 3.93 μg/mL (range 0.61−16.34 μg/mL). The median bone/plasma penetration ratio was 0.42 (range 0.14−0.95 μg/mL). Linezolid concentration in bone had a linear correlation with the drug concentration in plasma (r = 0.7873, p < 0.0001), while plasma concentration could explain 61.98% of the variation of concentration in bone (R2 = 0.6198). Notably, stratification analysis by sampling time demonstrated that samples collected 200−510 min after dosing had very good linear relationships between their bone and plasma concentrations (r = 0.9323). Linezolid penetrates from blood to bone efficiently, and the penetration further stabilizes ∼3 h after dosing.