A 60-year-old man comes to the physician because of a3 weeks history of intermittent low-grade fever and a worsening productive cough. During this time, he also has had a 4-kg (9-lb) weight loss despite no change in his appetite. He recently came back from rural China after attending a family wedding party. He has hypertension and takes lisinopril regularly. His temperature is 38.3 C (101 F), blood pressure is 110/80 mm Hg, pulse is 94/min, and respirations are 18/min. He weighs 60 kg (132.3 lb). Chest-x ray reveals a cavitary lesion on the right. Sputum culture is obtained. When exposed to drug A, isolates of the pathogen growing in culture quickly become less resistant to decoloration with an acid-alcohol agent and stop proliferating. Which of the following is drug A most likely to be?

Question

A 60-year-old man comes to the physician because of a3 weeks history of intermittent low-grade fever and a worsening productive cough. During this time, he also has had a 4-kg (9-lb) weight loss despite no change in his appetite. He recently came back from rural China after attending a family wedding party. He has hypertension and takes lisinopril regularly. His temperature is 38.3 C (101 F), blood pressure is 110/80 mm Hg, pulse is 94/min, and respirations are 18/min.  He weighs 60 kg (132.3 lb). Chest-x ray reveals a cavitary lesion on the right.  Sputum culture is obtained.  When exposed to drug A, isolates of the pathogen growing in culture quickly become less resistant to decoloration with an acid-alcohol agent and stop proliferating.  Which of the following is drug A most likely to be?

Quizplus · Accepted Answer

Eductional Objective: Isoniazid is an antimycobacterial agent that specifically inhibits the synthesis of mycolic acids, which are essential components of the unique mycobacterial peptidoglycan cell wall.  Without mycolic acids, the mycobacteria lose their acid-fastness and become unable to synthesize new cell walls or multiply.

A 60-Year-Old Man Comes to the Physician Because of A3