Piperacillin/tazobactam (Tazocin®, PTZ) 為一廣效性複方抗生素，廣泛用於院內感染的經驗性抗生素。本案例為54 歲男性因醫療照護相關肺炎而入院，長期使用PTZ 出現嗜中性白血球低下（WBC：2,440/mm3；絕對嗜中性球：440/mm3）。停藥後一週白血球上升至14,480/mm3，第9 天白血球攀升至54,500/mm3，停藥後第17天降至16,860/mm3。依據文獻查證，PTZ 造成骨髓抑制與劑量累積有相關性。藉由此案例提醒醫療人員，長期使用PTZ 須小心監測病人血球變化。若發生不良反應時應立即停藥，防止對病人造成更進一步的嚴重傷害。

Piperacillin/tazobactam (Tazocin®, PTZ) is a combination antibiotic with a broad spectrum of activity,and used in nosocomial infections. This case is a 54-year-old male with health-care associated pneumonia (HCAP), which was prolonged use of piperacillin/tazobactam with induced neutropenia (WBC: 2,440/mm3; absolute neutrophil count [ANC]: 440/mm3). Approximately one week after cessation of PTZ, laboratory data revealed that elevated WBC 14,480/mm3, ANC 4,923/mm3, WBC increased to 54,500/mm3 at day-9 after cessation, and recovered to 16,860/mm3 at day-17 after discontinued PTZ. From a literature review, PTZ causes bone marrow suppression correlated with cumulative dose. The purpose of this study was to recall the monitoring of blood counts carefully after long-term use of PTZ. PTZ should be discontinued immediately to prevent further serious injury when adverse reactions occurred as well.