Agranulocytosis Associated With Use of Sulfamethoxazole/Trimethoprim in a Healthy Adult

Purpose: A case of sulfamethoxazole/trimethoprim-induced agranulocytosis is reported. Summary: A 53-year-old healthy male presented to the emergency room with a fever of 102.7°F and was found to have a white blood cell (WBC) count of 0.6 × 10³ cells/μL with an absolute neutrophil count (ANC) of 0.0 x 10³ cells/μL. He had recently completed a 10-day course of sulfamethoxazole/trimethoprim for left lower extremity cellulitis. During admission, a bone marrow biopsy was performed which was not concerning for malignancy and no cause for the agranulocytosis other than the sulfamethoxazole/trimethoprim was identified. The agranulocytosis resolved after 6 days of hospitalization with a WBC count of 8.9 × 10³ cells/μL and an ANC of 4.1 x 10³cells/μL on the day of discharge. Conclusion: A 53-year-old male developed agranulocytosis after 10 days of sulfamethoxazole/trimethoprim therapy for the treatment of a skin and soft tissue infection. His neutropenia resolved after sulfamethoxazole/trimethoprim discontinuation.