This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Best rapid diagnostic test for etiology of acute pyogenic meningitis is? 
Select and explain. 
A. Pro calcitonin, B. Limulus test, C. Latex agglutination, D. Counterimmunoelectrophoresis
C: Latex agglutination
Answer: C: Latex agglutination 
Explanation: ANSWER: (C) Latex agglutinationREF: Clinical approach to infection in the compromised host by Robert H. Rubin, Lowell S. Young Page 175* Latex agglutination test is more rapid and sensitive than the counterimmunoelectrophoresis (CIE) in detection of etiological agent of pyogenic (bacterial) meningitis.One of these rapid diagnostic tests (preferably latex agglutination) should be performed on all CSF specimens from patients in whom bacterial meningitis is suspected if the CSF indices are consistent with the diagnosis and the CSF Gram stain is negativeLysate prepared from amoebocytes of horseshoe crab, Limulus polyphemus, is useful in suspected cases of gram negative meningitis in wThich positive test is due to presence of endotoxins.Recently procalcitonin has been evaluated s a marker to differentiate bacterial from viral meningitis