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Chapter 52: Antiprotozoal Drugs

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Which statement about antiprotozoal drugs is accurate?

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(A) Chloroquine is an inhibitor of plasmodial dihydrofolate reductase

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(B) Mefloquine destroys secondary exoerythrocytic schizonts

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(C) Primaquine is a blood schizonticide and does not affect secondary tissue schizonts

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(D) Proguanil complexes with double-stranded DNA-blocking replication

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(E) Trimethoprim-sulfamethoxazole is the drug of choice for Pneumocystis jiroveci pneumonia

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Proguanil (not chloroquine) is an inhibitor of dihydrofolate reductase. Primaquine (not mefloquine) is the drug that destroys secondary exoerythrocytic schizonts. TMP-SMZ is the drug of choice for Pneumocystis jiroveci pneumonia. The answer is E.

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Plasmodial resistance to chloroquine is due to

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(A) Change in receptor structure

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(B) Decreased accumulation of the drug in the food vacuole

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(C) Increased activity of DNA repair mechanisms

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(D) Increased synthesis of dihydrofolate reductase

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(E) Induction of drug-inactivating enzymes

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Resistance to chloroquine in P falciparum can result from decreased accumulation of the drug in the food vacuole caused by the activity of a transporter system encoded by the pfcrt gene. The answer is B.

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A traveler in a geographical region where chloroquine-resistant P falciparum is endemic used a drug for prophylaxis but nevertheless developed a severe attack of P vivax malaria.

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The drug used for prophylaxis was probably

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(A) Atovaquone

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(B) Iodoquinol

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(C) Mefloquine

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(D) Proguanil

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(E) Tetracycline

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Mefloquine is a recommended drug for prophylaxis in regions of the world where chloroquine-resistant P falciparum is endemic. One dose of mefloquine weekly starting before travel and continuing until 4 wk after leaving the region is the preferred regimen. Doxycycline (not tetracycline) is an alternative drug for this indication, as is atovaquone plus proguanil (Malarone). The answer is C.

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A traveler in a geographical region where chloroquine-resistant P falciparum is endemic used a drug for prophylaxis but nevertheless developed a severe attack of P vivax malaria.

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Which drug should be used for oral treatment of the acute attack of P vivax malaria but does not eradicate exoerythrocytic forms of the parasite?

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(A) Chloroquine

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