ABSTRACT
OBJECTIVE: Piperacillin/tazobactam (TZP ) is commonly used against multi-resistant nosocomial Pseudomonas infections. While TZP-induced thrombocytopenia is a well-known and easily diagnosed complication, we herein present an unusual case of spontaneous TZP-induced bleeding caused by platelet dysfunction. CASE SUMMARY: A 73-year-old-man experienced severe pulmonary hemorrhage and bloody diarrhea during the treatment with TZP for Pseudomonas aeruginosa ventilator-associated pneumonia. While both platelet count and coagulation tests were normal, platelet functional test revealed severely impaired ADP-dependent platelet aggregation. CONCLUSION: Platelet dysfunction is a little-known mechanism of TZP-induced bleeding. This is the second reported case of TZP-related bleeding that has been attributed to platelet dysfunction, and the first case report that has not been associated with surgery. While thrombocytopenia is easily recognized, this form of TZP-induced bleeding can be detected only by platelet functional tests.