血小板增生通常是感染、發炎、組織傷害及貧血等急性因素所引起的次發性反應，血小板增生與抗生素雖然尚未有明確的因果關係，但可能在使用抗生素後於感染改善期間發生。本案例為一位出生四天大的足月男嬰，因發燒自婦產科診所轉診至本院，腦脊髓液培養確診為Escherichia coli (E. coli) 引起之細菌性腦膜炎。病人在meropenem 治療8 天後血小板數上升至720 × 103/μL，明顯有增生的情況，3 天後再追蹤下降至529 × 103/μL，疑似有暫時性明顯增生。由於治療後病人沒有再發燒，C 反應蛋白 (C-reactive protein, CRP) 已下降，且未發生血栓或出血性併發症，故持續完成meropenem 的療程。病人在結束三週療程後出院，但隔日因發燒再入院，經腰椎穿刺結果仍為E. coli 感染。由於病人合併有硬膜下積膿，入院後除了延長meropenem 治療達六週外，也安排進行膿瘍引流手術。第二次入院在使用meropenem 治療8 天後，病人又發生血小板增生的情況，但上升幅度較第一次平緩。
前後兩次病人的血小板數在入院後皆先有下降的情況，但經過抗生素治療後卻發生次發性血小板增生，以Naranjo 藥物不良反應評分表評估因果關係為6 分，極有可能為meropenem 引起的暫時性血小板增生。因為文獻中較缺乏新生兒使用meropenem 的安全性文獻報告，且大多未再次投藥，希望此案例能有助於瞭解meropenem 與新生兒次發性血小板增生之間的關係。
Thrombocytosis usually occurs as a secondary response to acute events such as infection, inflammation, tissue damage, and hemorrhage. It may also be observed during recovery from infection following antimicrobial treatment; however, the nature of the association remains to be resolved. The case was a 4-day-old male term baby transferred from a local obstetric clinic due to fever. Cerebral spinal fluid (CSF) analysis and culture confirmed he had Escherichia coli (E. coli) bacterial meningitis and he was treated with meropenem since admission. On the eighth day of hospitalization, his platelet count escalated to 720 × 103/μL but decreased to 529 × 103/μL 3 days later.
Transient thrombocytosis was suspected. The patient had no fever, thrombotic or bleeding complications, and C-reactive protein (CRP) was decreased, all of which indicated adequate clinical response; therefore, meropenem was continued until discharge. One day after discharge he was re-admitted due to fever, repeated recovery of E. coli from CSF, and subdural empyema. He underwent surgical drainage for empyema and received 6-weeks’ meropenem for complicated meningitis. During the second course of meropenem treatment, a similar pattern to the first one of changes in platelet counts was observed, albeit to lesser extent. According to Naranjo adverse drug reaction probability scale, the association between meropenem and thrombocytosis was rated “probable” (score = 6). This case illustrates potential association between meropenem and thrombocytosis in neonates, adding to the paucity of literature in the safety profile of meropenem in neonates.
