For MDR TB, which drug class is commonly included in the treatment plan?

• A. Isoniazid
• B. A fluoroquinolone
• C. Rifampin
• D. Ethambutol

Answer: (B)

MDR-TB means the bacteria resist at least the two most powerful first-line drugs, isoniazid and rifampin, so therapy must shift to other drug classes. Among these, fluoroquinolones are routinely used because they have strong activity against Mycobacterium tuberculosis and penetrate well into infected tissues, helping to sterilize persistent bacilli. They form a core part of many MDR-TB regimens, typically alongside an injectable agent and several other second-line drugs to maximize efficacy and curb the development of further resistance. While isoniazid and rifampin are ineffective in MDR-TB due to resistance, and ethambutol can be used in some regimens, fluoroquinolones stand out as the commonly included class for treating this resistant form of TB.