Prevention of Pneumocystis jirovecii Pneumonia HIV-infected patients who have had P jirovecii pneumonia or who have a CD4+ T cell count < 200 / microL should receive prophylaxis with TMP / SMX 160/800 mg orally once a day or TMP / SMX 80/400 mg orally once a day; if this regimen is not tolerated, dapsone 100 mg orally once a day (or 50 mg orally twice a day) or aerosolized pentamidine 300 mg once a month can be used.