Chapter 23: Mycobacteria

Chapter 23: Mycobacteria

A 60-year-old man has a 5-month history of progressive weakness and a weight loss of 13 kg along with intermittent fever, chills, and a chronic cough productive of yellow sputum, occasionally streaked with blood. A sputum specimen is obtained, and numerous acid-fast bacteria are seen on the smear. Culture of the sputum is positive for M tuberculosis. Which treatment regimen is most appropriate for initial therapy?

(A) Isoniazid and rifampin

(B) Sulfamethoxazole–trimethoprim and streptomycin

(C) Isoniazid, rifampin, pyrazinamide, and ethambutol

(D) Isoniazid, cycloserine, and ciprofloxacin

(E) Rifampin and streptomycin

A 60-year-old man has a 5-month history of progressive weakness and a weight loss of 13 kg along with intermittent fever, chills, and a chronic cough productive of yellow sputum, occasionally streaked with blood. A sputum specimen is obtained, and numerous acid-fast bacteria are seen on the smear. Culture of the sputum is positive for M tuberculosis.

If the patient’s M tuberculosis isolate to be resistant to isoniazid, the likely mechanism for resistance is

(A) β-Lactamase

(B) Mutations in the catalase-peroxidase gene

(C) Alterations in the β subunit of RNA polymerase

(D) Mutations in the DNA gyrase gene

(E) Mutations in the genes encoding the S12 protein and 16S rRNA

A 47-year-old woman presents with a 3-month history of progressive cough, weight loss, and fever. Chest radiography shows bilateral cavitary disease suggestive of tuberculosis. Sputum culture grows an acid-fast bacillus that is a photochromogen (makes an orange pigment when exposed to light). The organism most likely is

(A) Mycobacterium tuberculosis

(B) Mycobacterium kansasii

(C) Mycobacterium gordonae

(D) Mycobacterium avium complex

(E) Mycobacterium fortuitum

A 31-year-old Asian woman is admitted to the hospital with a 7-week history of increasing malaise, myalgia, nonproductive cough, and shortness of breath. She has daily fevers of 38–39°C and a recent 5-kg weight loss. She had a negative chest radiograph when she entered the United States 7 years ago. The patient’s grandmother died of tuberculosis when the patient was an infant. A current chest radiograph is normal; results of other tests show a decreased hematocrit and liver function test abnormalities. Liver and bone marrow biopsies show granulomas with giant cells ...