Sam Myers is a 58-year-old man who is homeless and spends some nights in shelters and some nights on the street. For the past 6 weeks, he has experienced anorexia, weight loss, and low-grade fever. He...

Sam Myers is a 58-year-old man who is homeless and spends some nights in shelters and some nights on the street. For the past 6 weeks, he has experienced anorexia, weight loss, and low-grade fever. He comes to the local church health center and presents with a productive cough that has progressively worsened. A history and physical examination are completed with an evaluation for TB. The physical examination reveals the following findings: the patient’s height is 1.9 meters (6’1’’) and his weight is 56.2 kg (124 lb). He is emaciated and obviously malnourished. His vital signs are blood pressure, 112/82 mmHg; heart rate, 102 beats/min; respiratory rate, 26 breaths/min; and body temperature, 38.2°C (100.9°F). On auscultation, crackles are heard in the upper lung fields. The patient is experiencing moderate dyspnoea. Sam’s chest x-ray reveals multiple calcifications and two cavitary masses in the apical posterior segments of the upper lobes with lymphadenopathy also present. Sam admits to drinking alcohol almost every day and smoking at least one pack of cigarettes per day. He is admitted to a local acute care hospital for treatment of pulmonary TB.

1. Describe the mechanism of transmission for M. tuberculosis.

2. Discuss how Sam’s living conditions predispose him to pulmonary TB.

3. Why is Sam at high risk for hepatic-related adverse drug effects?