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Chapter 47: Antimycobacterial Drugs

A 45-year-old homeless man presents to the emergency department with fever, weight loss, and a productive cough. Chest x-ray shows right apical infiltrate and tuberculosis is suspected. He is started on empiric isoniazid (INH), rifampin, and pyrazinamide. The primary reason for the use of drug combinations in the treatment of this patient’s tuberculosis is:

(A) Delay or prevent the emergence of resistance

(B) Ensure patient compliance with the drug regimen

(C) Increase antibacterial activity synergistically

(D) Provide prophylaxis against other bacterial infections

(E) Reduce the incidence of adverse effects

Although it is sometimes possible to achieve synergistic effects against mycobacteria with drug combinations, the primary reason for their use is to delay the emergence of resistance. The answer is A.

A 21-year-old woman from Southeast Asia has been staying with family members in the United States for the last 3 months and is looking after her sister’s preschool children during the day. Because she has difficulty with the English language, her sister escorts her to the emergency department of a local hospital. She tells the staff that her sister has been feeling very tired for the last month, has a poor appetite, and has lost weight. The patient has been feeling somewhat better lately except for a cough that produces a greenish sputum, sometimes specked with blood. With the exception of rales in the left upper lobe, the physical examination is unremarkable and she does not seem to be acutely ill. Laboratory values show a white blood count of 12,000/μL and a hematocrit of 33%. Chest x-ray film reveals an infiltrate in the left upper lobe with a possible cavity. A Gram-stained smear of the sputum shows mixed flora with no dominance. An acid-fast stain reveals many thin rods of pinkish hue. A preliminary diagnosis is made of pulmonary tuberculosis. Sputum is sent to the laboratory for culture.

At this point, the most appropriate course of action is to

(A) Hospitalize the patient and start treatment with 4 antitubercular drugs

(B) Hospitalize the patient and start treatment with rifampin

(C) Prescribe INH for prophylaxis and send the patient home to await culture results

(D) Provide no drugs and send the patient home to await culture results

(E) Treat the patient with INH plus rifampin

Despite the fact that this patient does not appear to be acutely ill, she would in most cases be treated with ...

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