Vancomycin-Induced Thrombocytopenia: A Challenge and Rechallenge

Abstract

Objective To report a case of thrombocytopenia apparently associated with vancomycin use. Case Summary A 58-year-old white man was admitted to the hospital with chronic osteomyelitis of the foot due to methicillin-resistant Staphylococcus aureus that later spread hematogenously to the cervical vertebrae. During the first course of therapy with vancomycin, his platelet count decreased from 397 × 103/mm3 to 22 × 103/mm3. After discontinuation of the drug, it increased to 310 × 103/mm3. During the second course of vancomycin, the platelet count decreased to 77 × 103/mm3, and increased to 404 × 103/mm3 after discontinuation of the drug. Discussion Vancomycin has been reported as a rare cause of thrombocytopenia. Thrombocytopenia can occur as an adverse drug reaction by the following three mechanisms: direct toxic effect, drug absorption (hapten) formation, and an “innocent bystander” immune response. Conclusions We suspect that the thrombocytopenia in this patient, which involved an increased number of megakaryocytes in the bone marrow, was due to vancomycin.