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Chapter 47: Antimycobacterial Drugs

The primary reason for the use of drug combinations in the treatment of tuberculosis is to

(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 mo 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 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 isoniazid 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 isoniazid plus rifampin

Despite the fact that this patient does not appear to be acutely ill, she would in most cases be treated with 4 drugs that have activity against M tuberculosis. This is because organisms infecting patients from Southeast Asia are commonly INH-resistant, and coverage must be provided with 3 other antituberculosis drugs in addition to isoniazid. This patient should ...

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