This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
XDR-TB is resistant to - 
Select and explain. 
A. AKT(HRZE), B. HRKN, C. HRKO, D. HREEt
C: HRKO
Answer: C: HRKO 
Explanation: Extensively drug resistant TB is defined as resistance to atleast rifampicin, & isoniazid,in addition to any quinolone & atleast one injectable second line agent(kanamycin). Reference: Harrison20th edition pg 1079