Review Question - QID 106834

This HIV+ patient with a CD4 count of 27 cells/uL is suffering from a disseminated mycobacterium avium-intracellulare complex (MAC) infection. A macrolide, such as azithromycin or clarithromycin, should be given to HIV+ patients with a CD4 count less than 50 cells/uL in order to prevent MAC infections.

If a patient is unable to tolerate or has a contraindication to the macrolides, rifabutin may be used as an alternative agent for MAC prophylaxis. If the clinical picture suggests that a patient may have an active MAC infection at the time of starting MAC antibiotic prophylaxis (when CD4 count drops below 50), blood cultures should first be obtained to rule out this possibility, as the treatment regimen of MAC differs from prophylaxis. Treatment of disseminated MAC requires the addition of either ethambutol or rifabutin to the macrolide (azithromycin or clarithromycin). In a patient with disseminated MAC infection, after effective anti-retroviral therapy is resumed, the patient's CD4 count must rise to greater than 100 cells/uL for a time period of 3 months before it is appropriate to discontinue MAC prophylaxis.

Figure A is a chest radiograph of a patient with disseminated mycobacterium intracellulare infection with concomitant pulmonary involvement; note the patchy, ground-glass opacity in the left lung.

Incorrect Answers:
Answer 1: Although isoniazid is a common agent in the treatment of M. tuberculosis infections, it does not have a role in the treatment or prevention of MAC infections in HIV+ patients.
Answer 2: All HIV patients should receive the pnemococcal vaccine; however, this patient is suffering from disseminated MAC infection, not pneumococcal pneumonia.
Answer 3: Trimethoprim-sulfamethoxazole is recommended for patients with CD4 counts less than 200 cells/uL in order to prevent pneumocystis jiroveci pneumonia. TMP-SMX is also useful to suppress and prevent reactivation of toxoplasmosis in patients with CD4 count less than 100 cells/uL and positive toxoplasmosis serologies.
Answer 5: Although all HIV patients should receive vaccination against hepatitis B, it would not have prevented the development of disseminated MAC infection in this patient.