Piperacillin–Tazobactam-Induced Immune Thrombocytopenia: A Case Report

Drug-induced immune thrombocytopenia is an isolated thrombocytopenia caused by accelerated platelet destruction from drug-dependent, platelet-reactive antibodies. Heparin-induced thrombocytopenia is the most common drug-induced immune thrombocytopenia. Common implicated antibiotics for drug-induced immune thrombocytopenia include ceftriaxone, trimethoprim–sulfamethoxazole, vancomycin, and penicillin. The platelet nadir can be less than 20 × 10 (9)/L and typically occurs within 1 to 2 weeks of exposure to the inciting drug. Although rare, drug-induced immune thrombocytopenia can be fatal. Diagnosis is made by excluding other causes of thrombocytopenia. Laboratory testing for drug-dependent antiplatelet antibodies is often helpful but not required. Thrombocytopenia typically improves within 1 to 2 days of drug discontinuation and platelet count returns to normal within a week. Identifying and discontinuing the implicated medication is key to prevention of serious complications. A patient case of drug-induced immune thrombocytopenia is described after initiation of empiric piperacillin–tazobactam for refractory right foot cellulitis in the setting of right fourth toe diabetic ulcer.