Cycloserine for Treatment of Multidrug-Resistant Tuberculosis in China: A Retrospective Observational Study

Objectives Cycloserine is crucial in multidrug-resistant tuberculosis (MDR-TB) treatment. Although extensive research has been carried out on MDR-TB, most researchers have not treated cycloserine in much detail. Therefore, we evaluate the efficacy and safety of cycloserine and seek to clarify the role of cycloserine for treatment of simple MDR-TB, pre-extensively drug-resistant tuberculosis (pre-XDR-TB), and extensively drug-resistant tuberculosis (XDR-TB). Patients and methods A retrospective observational study was performed in China. We determined the treatment outcome as the primary outcome for 144 cycloserine-treated and 181 cycloserine-nontreated patients according to the definitions of WHO. The proportion of patients with sputum-culture conversion and the frequency of adverse drug reactions related to cycloserine were assessed as well. Results Among 325 MDR-TB patients, 144 were treated with cycloserine and 100 (69.4%) out of 144 successfully completed treatment. Compared with patients in non-cycloserine group, the hazard ratio of any unfavorable treatment outcome was 0.53 (95%CI: 0.35-0.81, P =0.003). Culture conversion rate at the intensive phase was similar whether cycloserine was administered or not ( P =0.703). Of the 144 patients treated with cycloserine, a total of 16 (11.1%) patients experienced side-effects related to cycloserine, including 7 patients who discontinued cycloserine permanently. Conclusions Cycloserine could be an attractive agent to treat MDR-TB. Its safety profile warrants use in the most of MDR-TB cases. Cycloserine significantly improved the chance of favorable outcome for patients with simple MDR-TB but not pre-XDR-TB and XDR-TB. More aggressive regimens might be required for pre-XDR-TB or XDR-TB patients.