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Chapter 23: Mycobacteria
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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?
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(A) Isoniazid and rifampin
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(B) Sulfamethoxazole–trimethoprim and streptomycin
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(C) Isoniazid, rifampin, pyrazinamide, and ethambutol
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(D) Isoniazid, cycloserine, and ciprofloxacin
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(E) Rifampin and streptomycin
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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.
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If the patient’s M tuberculosis isolate to be resistant to isoniazid, the likely mechanism for resistance is
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(B) Mutations in the catalase-peroxidase gene
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(C) Alterations in the β subunit of RNA polymerase
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(D) Mutations in the DNA gyrase gene
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(E) Mutations in the genes encoding the S12 protein and 16S rRNA
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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
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(A) Mycobacterium tuberculosis
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(B) Mycobacterium kansasii
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(C) Mycobacterium gordonae
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(D) Mycobacterium avium complex
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(E) Mycobacterium fortuitum
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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 ...