Piperacillin-Tazobactam Induced Rapid Severe Thrombocytopenia Without Known Exposure.

Thrombocytopenia is one of the commonly encountered laboratory abnormalities in the inpatient setting. The process of excluding life-threatening causes can be daunting and may result in overlooking iatrogenic sources such as medications. Antibiotics are known culprits; however, there are limited reports of rapid and severe onset thrombocytopenia following piperacillin-tazobactam (TZP) that were frequently observed in critically ill or immunocompromised patients with previous exposure to the antibiotic. This case describes a patient being treated for a soft tissue infection with vancomycin and TZP. Initiation of antimicrobial therapy resulted in severe thrombocytopenia and a platelet nadir of approximately 4,000 within 24 hours of the first doses. Thrombocytopenia resolved within three days of TZP withdrawal. To the best of our knowledge, there have not been any cases described of rapid drug-induced thrombocytopenia without previous exposure to the medication. Medications should always be reviewed when evaluating a patient with rapid and severe thrombocytopenia, which can obviate the need for unnecessary invasive or non-invasive treatments.