Linezolid in the treatment of multidrug-resistant tuberculosis.

Background: Linezolid is a new antibiotic with activity against Mycobacterium tuberculosis in vitro and in animal studies. Several small case series suggest that linezolid is poorly tolerated because of the side effects of anemia/thrombocytopenia and peripheral neuropathy. To characterize our clinical experience with linezolid, the California Department of Public Health Tuberculosis Control Branch's Multidrug-Resistant Tuberculosis (MDR-TB) Service reviewed cases in which the MDR-TB treatment regimens included linezolid therapy.
Methods: Record review was performed for 30 patients treated with linezolid as part of an MDR-TB regimen. Data were collected on clinical and microbiological characteristics, linezolid tolerability, and treatment outcomes. The dosage of linezolid was 600 mg daily. Vitamin B6 at a dosage of 50-100 mg daily was used to mitigate hematologic toxicity.
Results: During 2003-2007, 30 patients received linezolid for the treatment of MDR-TB. Patients had isolates resistant to a median of 5 drugs (range, 2-13 drugs). Of the 30 cases, 29 (97%) were pulmonary; of these 29, 21 (72%) had positive results of acid-fast bacilli smear, and 16 (55%) were cavitary. Culture conversion occurred in all pulmonary cases at a median of 7 weeks. At data censure (31 December 2008), 22 (73%) of 30 patients had successfully completed treatment. Five continued to receive treatment. There were no deaths. Three patients had a poor outcome, including 2 defaults and 1 treatment failure. Side effects occurred in 9 patients, including peripheral and optic neuropathy, anemia/thrombocytopenia, rash, and diarrhea. However, only 3 patients stopped linezolid treatment because of side effects.
Conclusions: Linezolid was well tolerated, had low rates of discontinuation, and may have efficacy in the treatment of MDR-TB.