Sulfamethoxazole-trimethoprim-induced Pneumonitis in a Patient with Hemophilia B who was Infected with the Human Immunodeficiency Virus

: Severe cellular immunosuppression developed in a 25-year-old man with hemophilia B who was infected with the human immunodeficiency virus (HIV). Four days after administration of sulfamethoxazole-trimethoprim (SMX-TMP) for prophylaxis against Pneumocystis carinii pneumonia (PCP), diffuse uptake of both lungs was confirmed on a 67Ga scintigram. Reticular shadows were also seen throughout both lung fields on a chest CT scan. These findings were compatible with PCP, according to the guidelines for presumptive diagnosis of the acquired immunodeficiency syndrome, published by the Centers for Disease Control and Prevention. The dose of SMX-TMP was increased, but interstitial pneumonitis worsened and was accompanied by fever, skin rash, and liver dysfunction, which are common in HIV-infected patients receiving SMX-TMP. No evidence of PCP or of any other opportunistic infection was found by bronchoalveolar lavage. Adverse reactions diminished after SMX-TMP administration was stopped. The 67Ga scintigram and chest CT findings also returned to normal. We concluded that the interstitial pneumonitis was induced by SMX-TMP. SMX-TMP is the first choice anti-PCP drug, but a high incidence of adverse reactions in patients with HIV infection has been reported. Therefore the possibility of SMX-TMP-related pulmonary toxicity must be considered in HIV-infected patients.