PTH and tuberculosis: First, although BD Bactec MGIT 960 is recommended as the gold standard for detecting susceptibility to second-line anti-TB drugs of MTB isolates (WHO, 2008), the poor reliability and reproducibility have been noted in PTH testing compared with other second-line drugs by several studies (Krüüner et al., 2006; Rüsch-Gerdes et al., 2006; van Ingen et al., 2010).