62.針對細菌性腦膜炎病人的診斷，下列有關腦脊髓液（CSF）檢查之敘述何者錯誤？
(A)超過一半病人的 CSF 會有 polymorphonuclear（PMN）白血球增加至＞100 cells/μL 現象
(B)超過一半病人的 CSF/serum glucose 比值＜0.4
(C)超過一半病人的 CSF 細菌培養會是陽性
(D)病人 CSF 進行 Gram's stain 檢查幫助不大，只有大約 20%可以看到致病原

Diagnostic studies (NEJM 2017;388:3036)
• Blood cultures x2 before abx
• WBC count: >10,000 in >90% of bacterial meningitis in healthy
hosts
• Head CT to r/o mass effect before LP if ≥1 high-risk feature:
immunosupp., h/o CNS disease, new-onset seizure, focal neuro
findings, papilledema, GCS <15 (CID 2004;39:1267)
• Lumbar puncture with opening pressure (NEJM 2006;355:e12)
Send CSF for cell count and differential, glucose, protein, Gram
stain, bacterial cx
Additional CSF studies based on clinical suspicion: AFB smear/cx
(or MTb PCR), cryptococcal Ag, fungal cx, VDRL, PCR (HSV,
VZV, enteroviral), cytology
CSF Gram stain has 30-90% Se; cx 80-90% Se if LP done prior
to abx though abx should not be delayed for LP if there is
concern for bacterial meningitis
Rule of 2s: CSF WBC >2k, gluc <20, TP >200 has >98% Sp for
bacterial meningitis