Efficacy of using trimethoprim‐sulfamethoxazole prophylaxis in an adult patient with autoimmune neutropenia

A 63‐year‐old man was admitted for pneumonia with neutropenia. After the pneumonia resolved with administration of antibiotics and granulocyte colony‐stimulating factor, he was diagnosed with autoimmune neutropenia (AIN) on the basis of bone marrow findings and positive antineutrophil antibodies. He had recurring high fever once or twice a month with productive cough and an elevated serum C‐reactive protein level. However, after the initiation of treatment with oral trimethoprim‐sulfamethoxazole (TMP/SMX), the respiratory tract infection no longer recurred. The standard management for adults with AIN has not been established. In our case, the recurrent infection was resolved with TMP/SMX prophylaxis. Thus, TMP/SMX prophylaxis may be beneficial for managing adults with AIN.