Effect of traumatic brain injury on the trough concentration of linezolid in patients with hospital-acquired pneumonia.

To investigate the effect of traumatic brain injury (TBI) on linezolid trough concentration (Cmin) and Gram-positive bacteria eradication in patients with hospital-acquired pneumonia (HAP). HAP patients who treated with linezolid were collected and divided into TBI and non-TBI groups. Differences in the linezolid Cmin, Gram-positive bacterial eradication, clinical treatment success, and adverse reactions were analyzed between the two groups. A total of 177 patients were enrolled in the study, including 57 with TBI and 120 without TBI. After 1:1 propensity score matching (PSM), 46 patients with well-balanced baseline levels were enrolled. Linezolid Cmin and Gram-positive bacterial eradication rate were lower in TBI group than in non-TBI group [2.06 (0.89, 6.89) mg/L, 6.70 (3.09, 13.48) mg/L, P < 0.001; 69.0% vs. 90.9%, P = 0.029]. Linezolid-induced thrombocytopenia (LIT) and severe LIT occurred in fewer patients in TBI group than in non-TBI group (4.3% vs. 28.3%, P = 0.005; 2.2% vs. 17.4%, P = 0.035). The linezolid Cmin for the predicted eradication of Gram-positive bacterial was 1.62 mg/L. Further studies have found that the use of mannitol, glycerin fructose and high fluid intake and output may be responsible for the low Cmin of linezolid in TBI group. Patients in TBI group had lower linezolid Cmin and Gram-positive bacterial eradication rates compared with those in non-TBI group. A lower Cmin level may predict a decrease in Gram-positive bacterial eradication rates, and patients with concomitant TBI may need to explore higher linezolid doses.