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  1. #1
    usmlemate is offline Junior Member
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    Prophylaxis for Toxoplasma Encephalitis

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    A 28-year-old HIV-infected woman from rural Mexico presents to clinic for primary care. She has a history of Pneumocystis pneumonia and oral candidiasis. In the past, she received treatment for latent tuberculosis. Serologic testing detects antibodies to Toxoplasma (IgG) and her current CD4 count is 85 cells/mm3. Her current medications are dapsone and clotrimazole (Mycelex) troches; she has declined antiretroviral therapy. She has a history of a mild rash when taking trimethoprim-sulfamethoxazole (Bactrim, Septra) approximately 1 year ago. She is sexually active, does not routinely use effective birth control measures, and her last menstrual period was more than 2 months ago.

    Which of the following is TRUE regarding prophylaxis for Toxoplasma encephalitis in this patient:

    A. The patient has an IgG antibody to Toxoplasma that is evidence of immunity to infection and she does not need prophylaxis for Toxoplasma encephalitis.

    B. The patient does need prophylaxis for Toxoplasma encephalitis and the dapsone she takes for Pneumocystis prophylaxis will provide protection against Toxoplasma encephalitis.

    C. The patient does need prophylaxis for Toxoplasma encephalitis. Dapsone alone does not provide sufficient protection against reactivation of Toxoplasma; she should take pyrimethamine in addition to dapsone.

    D. If possible, the patient should be desensitized to and then treated with trimethoprim-sulfamethoxazole for prophylaxis against both Pneumocystis pneumonia and Toxoplasma encephalitis.

    E. The patient should be prescribed atovaquone as prophylaxis for Pneumocystis pneumonia and Toxoplasma encephalitis.

  2. #2
    usmlemate is offline Junior Member
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    Re: Prophylaxis for Toxoplasma Encephalitis

    Quote Originally Posted by usmlemate
    A 28-year-old HIV-infected woman from rural Mexico presents to clinic for primary care. She has a history of Pneumocystis pneumonia and oral candidiasis. In the past, she received treatment for latent tuberculosis. Serologic testing detects antibodies to Toxoplasma (IgG) and her current CD4 count is 85 cells/mm3. Her current medications are dapsone and clotrimazole (Mycelex) troches; she has declined antiretroviral therapy. She has a history of a mild rash when taking trimethoprim-sulfamethoxazole (Bactrim, Septra) approximately 1 year ago. She is sexually active, does not routinely use effective birth control measures, and her last menstrual period was more than 2 months ago.

    Which of the following is TRUE regarding prophylaxis for Toxoplasma encephalitis in this patient:

    A. The patient has an IgG antibody to Toxoplasma that is evidence of immunity to infection and she does not need prophylaxis for Toxoplasma encephalitis.

    B. The patient does need prophylaxis for Toxoplasma encephalitis and the dapsone she takes for Pneumocystis prophylaxis will provide protection against Toxoplasma encephalitis.

    C. The patient does need prophylaxis for Toxoplasma encephalitis. Dapsone alone does not provide sufficient protection against reactivation of Toxoplasma; she should take pyrimethamine in addition to dapsone.

    D. If possible, the patient should be desensitized to and then treated with trimethoprim-sulfamethoxazole for prophylaxis against both Pneumocystis pneumonia and Toxoplasma encephalitis.

    E. The patient should be prescribed atovaquone as prophylaxis for Pneumocystis pneumonia and Toxoplasma encephalitis.
    The correct answer is D. The simplest and most effective prophylaxis for both Pneumocystis pneumonia and Toxoplasma encephalitis is trimethoprim-sulfamethoxazole. Many HIV-infected patients with a history of allergy to “sulfa” drugs can undergo trimethoprim-sulfamethoxazole desensitization. In addition, trimethoprim-sulfamethoxazole is recommended as first line prophylactic therapy against Toxoplasma encephalitis in HIV-infected pregnant women.

    Answer A is incorrect. An IgG antibody implies previous and likely persistent, latent infection with Toxoplasma gondii, and this organism can reactivate in the presence of depressed immunity. All HIV-infected patients who have IgG antibodies against Toxoplasma and CD4 counts less than 100 cells/mm3 should be prescribed prophylactic therapy to prevent Toxoplasma encephalitis.

    Answer B is incorrect. The patient does need prophylaxis for Toxoplasma encephalitis, but dapsone alone is not sufficient prophylaxis.

    Answer C is incorrect. Dapsone plus pyrimethamine is an acceptable alternative to trimethoprim-sulfamethoxazole for primary prophylaxis against Toxoplasma encephalitis, but it is not the preferred regimen. In addition, leucovorin must be taken with pyrimethamine to prevent leukopenia, making this regimen even more complex. Finally, this patient is not using reliable birth control, and the use of dapsone plus pyrimethamine is not recommended for pregnant women. Trimethoprim-sulfamethoxazole is the recommended drug for prophylaxis of Pneumocystis pneumonia and Toxoplasma encephalitis for pregnant women.

    Answer E is incorrect. Atovaquone has activity against both Pneumocystis jiroveci and Toxoplasma gondii, but there is less published experience on its use for Toxoplasma encephalitis prophylaxis than for trimethoprim-sulfamethoxazole. Furthermore, it is unknown whether pyrimethamine needs to be used with atovaquone for Toxoplasma encephalitis prophylaxis, and pyrimethamine is not recommended for pregnant women.

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