What is the standard first-line therapy for mild-to-moderate Pneumocystis jirovecii pneumonia if no sulfa allergy?

• A. TMP-SMX (trimethoprim-sulfamethoxazole)
• B. Dapsone with trimethoprim
• C. Clindamycin with primaquine
• D. Pentamidine

Answer: (B)

The main idea here is that for Pneumocystis jirovecii pneumonia in patients who have no sulfa allergy, the best first-line treatment is high-dose TMP-SMX. This combination is highly effective against Pneumocystis, offers good lung penetration, and has a long track record of success in mild-to-moderate disease. Dosing is typically a high-dose regimen of trimethoprim-sulfamethoxazole given for about 14 to 21 days, with consideration of adjunctive corticosteroids if the patient is significantly hypoxemic.

Dapsone with trimethoprim is reserved for people who cannot take TMP-SMX due to a sulfa allergy or intolerance, not for those without allergy. Other alternatives, such as clindamycin with primaquine, atovaquone, or pentamidine, are also considered when TMP-SMX cannot be used, but they are not the standard first-line in patients without sulfa allergy.