A 38-year-old man comes to the physician because of fever, malaise, productive cough, and left-sided chest pain for 2 weeks. He was diagnosed with HIV infection 1 year ago. He currently stays at a homeless shelter. He has smoked one pack of cigarettes daily for 22 years. He is receiving combined antiretroviral therapy but sometimes misses doses. His temperature is 38.6°C (101.5°F), pulse is 106/min, and blood pressure is 125/85 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 94%. Chest x-ray reveals a right apical lung infiltrate and cavitary lesion. He is placed in respiratory isolation, and appropriate empiric therapy is started. The cavitary lesions seen in this patient most likely formed through which of the following pathogenic mechanisms?

Question

A 38-year-old man comes to the physician because of fever, malaise, productive cough, and left-sided chest pain for 2 weeks. He was diagnosed with HIV infection 1 year ago. He currently stays at a homeless shelter. He has smoked one pack of cigarettes daily for 22 years. He is receiving combined antiretroviral therapy but sometimes misses doses. His temperature is 38.6°C (101.5°F), pulse is 106/min, and blood pressure is 125/85 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 94%. Chest x-ray reveals a right apical lung infiltrate and cavitary lesion.  He is placed in respiratory isolation, and appropriate empiric therapy is started.  The cavitary lesions seen in this patient most likely formed through which of the following pathogenic mechanisms?

Quizplus · Accepted Answer

Eductional Objective: Control of Mycobacterium tuberculosis infection is mediated primarily by activated macrophages, which surround extracellular mycobacteria and wall them off within granulomas.  The release of digestive enzymes by these cells not only helps control the infection, but also leads to damage of the surrounding tissue and the formation of cavitary lung lesions.

A 38-Year-Old Man Comes to the Physician Because of Fever