Differential distribution of linezolid in diseased and nondiseased bones in patients with spinal tuberculosis.

BACKGROUND: Linezolid exhibits antibacterial activity against sensitive and drug-resistant strains of Mycobacterium tuberculosis. Knowledge on the distribution of linezolid in different types of bones in patients with spinal tuberculosis (TB) is lacking, which limits the pharmacokinetic and pharmacodynamic studies of linezolid. This study aimed to evaluate the distribution of linezolid in diseased and nondiseased bones in patients with spinal TB.

METHODS: Spinal TB patients treated with linezolid-containing regimens and whose diseased and nondiseased bones were collected during surgery were enrolled retrospectively from January 2017 to February 2022. Blood, nondiseased bones, and diseased bones were collected simultaneously during the operation. Linezolid concentrations in the plasma, nondiseased bones, and diseased bones were subjected to high-performance liquid chromatography-tandem mass spectrometry.

RESULTS: Seven eligible spinal TB patients, including one rifampicin-resistant case, were enrolled. Following a 600 mg oral administration of linezolid before surgery, the median concentrations of linezolid in plasma, nondiseased bone, and diseased bone of the seven patients were 8.23, 1.01, and 2.13 mg/L, respectively. The mean ratios of linezolid concentration in nondiseased bones/plasma, diseased bones/plasma and diseased bones/nondiseased bones reached 0.26, 0.49, and 2.27, respectively. The diseased bones/plasma presented a higher mean ratio of linezolid concentration than nondiseased bones/plasma, and the difference was statistically significant (t = 2.55, p = 0.025). Pearson's correlation analysis showed the positively correlation of linezolid concentrations in diseased and nondiseased bones (r = 0.810, p = 0.027).

CONCLUSIONS: Linezolid exhibits a higher concentration distribution in diseased bones than in nondiseased bones.