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    usmlemate is offline Junior Member
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    Prophylaxis for Pneumocystis Pneumonia

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    A 38-year-old man presents for care after being recently diagnosed with HIV infection. He has been diagnosed with community-acquired pneumonia 3 times in the last year. He takes no medications and thinks he may be allergic to "sulfa" since he developed some pruritis and a mild rash while taking trimethoprim-sulfamethoxazole (Bactrim, Septra) for one of his episodes of pneumonia. He currently has no respiratory symptoms and his physical examination is notable for seborrheic dermatitis, poor dentition, and obvious oral candidiasis. He is seropositive for Toxoplasma gondii.

    Which of the following is true regarding prophylaxis for Pneumocystis pneumonia?

    A. This patient may be a candidate for Pneumocystis pneumonia prophylaxis, but he should be considered for prophylaxis only if his CD4 cell count is less than 200 cells/mm3.

    B. The patient should be started on prophylaxis for Pneumocystis pneumonia, but given his history of pruritis and rash, trimethoprim-sulfamethoxazole would not be an option.

    C. The patient should be started on Pneumocystis pneumonia prophylaxis using trimethoprim-sulfamethoxazole. You should consider introducing trimethoprim-sulfamethoxazole desensitization given his possible allergy to "sulfa".

    D. The patient has AIDS and active oral candidiasis. He should be admitted to the hospital and bronchoscopy performed to rule out active Pneumocystis pneumonia prior to receiving prophylaxis.

    E. Prior to initiating prophylaxis, a sputum sample should be sent to perform Pneumocystis jiroveci (formerly Pneumocystis carinii) resistance testing.

  2. #2
    usmlemate is offline Junior Member
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    Re: Prophylaxis for Pneumocystis Pneumonia

    Quote Originally Posted by usmlemate
    A 38-year-old man presents for care after being recently diagnosed with HIV infection. He has been diagnosed with community-acquired pneumonia 3 times in the last year. He takes no medications and thinks he may be allergic to "sulfa" since he developed some pruritis and a mild rash while taking trimethoprim-sulfamethoxazole (Bactrim, Septra) for one of his episodes of pneumonia. He currently has no respiratory symptoms and his physical examination is notable for seborrheic dermatitis, poor dentition, and obvious oral candidiasis. He is seropositive for Toxoplasma gondii.

    Which of the following is true regarding prophylaxis for Pneumocystis pneumonia?

    A. This patient may be a candidate for Pneumocystis pneumonia prophylaxis, but he should be considered for prophylaxis only if his CD4 cell count is less than 200 cells/mm3.

    B. The patient should be started on prophylaxis for Pneumocystis pneumonia, but given his history of pruritis and rash, trimethoprim-sulfamethoxazole would not be an option.

    C. The patient should be started on Pneumocystis pneumonia prophylaxis using trimethoprim-sulfamethoxazole. You should consider introducing trimethoprim-sulfamethoxazole desensitization given his possible allergy to "sulfa".

    D. The patient has AIDS and active oral candidiasis. He should be admitted to the hospital and bronchoscopy performed to rule out active Pneumocystis pneumonia prior to receiving prophylaxis.

    E. Prior to initiating prophylaxis, a sputum sample should be sent to perform Pneumocystis jiroveci (formerly Pneumocystis carinii) resistance testing.
    The correct answer is C. Trimethoprim-sulfamethoxazole is the preferred agent for Pneumocystis pneumonia prophylaxis. Furthermore, trimethoprim-sulfamethoxazole provides protection against Toxoplasma encephalitis and may provide some benefit in preventing further episodes of community-acquired pneumonia. Many HIV-infected patients with a true sulfonamide allergy can be desensitized to trimethoprim-sulfamethoxazole.

    Anser A is incorrect. Regardless of his CD4 cell count, this HIV-infected patient should receive Pneumocystis prophylaxis because he has oral candidiasis. Moreover, he has a category C AIDS diagnosis based on his history of recurrent pneumonia (2 or more episodes of pneumonia in a 1-year period is an AIDS-defining illness). Persons with an AIDS-defining illness, but who do not otherwise qualify for Pneumocystis prophylaxis should be considered for prophylaxis.


    Answer B is incorrect. A history of trimethoprim-sulfamethoxazole rash would not be an absolute contraindication to using trimethoprim-sulfamethoxazole for Pneumocystis prophylaxis, except in those persons who had a serious or life-threatening reaction, such as *******-Johnson syndrome. Many HIV-infected patients with a history of trimethoprim-sulfamethoxazole rash can undergo successful desensitization to trimethoprim-sulfamethoxazole.

    Answer D is incorrect. A diagnosis of AIDS and oral candidiasis are not justification for hospital admission. The patient has no active respiratory symptoms and thus does not require bronchoscopy to evaluate for Pneumocystis pneumonia prior to initiating prophylaxis.

    Answer E is incorrect. Pneumocystis jiroveci is extraordinarily difficult to culture in vitro; therefore traditional resistance testing cannot be performed. Sequence analysis of the dihydropteroate synthase gene can identify mutations associated with sulfamethoxazole resistance, but these tests are not routinely available and correlation between resistance and treatment failure have not been well established.

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    IMG SURVIVOR is offline Moderator 536 points
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    This is an interesting concept
    Moderator: USMLE AND Residency Forums.

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    why even bother with the obvious. Just know where you are need it and where you can help the most.

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