(HealthDay News) – Adding linezolid to ongoing background therapy for the treatment of extensively drug-resistant (XDR) pulmonary tuberculosis is effective in achieving culture conversion, but patients must be carefully monitored for adverse events, according to research published in the Oct. 18 issue of the New England Journal of Medicine.

Myungsun Lee, M.D., of the International Tuberculosis Research Center in Changwon, South Korea, and colleagues conducted a study involving 39 patients with sputum-culture-positive XDR tuberculosis who had not responded to any available chemotherapeutic option during the previous six months. Participants were randomized to receive linezolid 600mg starting immediately or after two months, with no change in background regimen. After confirmed sputum-smear conversion or at four months, patients were randomized again to 600mg linezolid or 300mg linezolid for at least 18 months.

By four months, the researchers found that 79 and 35 percent of the immediate-start and delayed-start groups, respectively, had culture conversion. Within six months after starting linezolid, 87 percent of patients had a negative sputum culture. Overall, 82 percent of patients displayed clinically significant adverse events that were possibly or probably linked to linezolid, and three patients stopped treatment. Dose reduction to 300mg per day resulted in fewer adverse events. Therapy was completed by 13 patients and they did not experience a relapse. Acquired linezolid resistance was noted in four cases.

“Linezolid is effective at achieving culture conversion among patients with treatment-refractory XDR pulmonary tuberculosis, but patients must be monitored carefully for adverse events,” the authors write.

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