They also looked at the genetic lineage of the Mycobacterium tuberculosis bacteria infecting the patients. 他们还研究了感染患者的结核分枝杆菌的遗传世系。
It could also be caused by genetic differences between M. tuberculosis populations in different parts of the world, she adds. 她还说，这也可能是由于世界不同地方的结核分枝杆菌种群的遗传差异造成的。
