Follow-up of patients with multidrug resistant tuberculosis four years after standardized first-line drug treatment. oleh Guang Xue He, Yan Guang Xie, Li Xia Wang, Martien W Borgdorff, Marieke J van der Werf, Ji Huan Fan, Xing Lu Yan, Fa Bin Li, Xue Zhi Zhang, Yan Lin Zhao, Susan van den Hof