CSF examination of a patient with chronic meningitis shows clear fluid that forms a spider-web-like coagulum on standing, lymphocytic pleocytosis, markedly elevated protein, and low glucose. Acid-fast bacilli are later demonstrated. The cobweb coagulum formation in tuberculous meningitis is attributed to:

• A Very high neutrophil count with lysed cellular debris
• B High fibrinogen content of the CSF precipitating as fibrin strands ✓
• C Free mycolic acid released from bacilli polymerizing in vitro
• D Elevated chloride levels causing protein denaturation

Explanation

Tuberculous meningitis CSF typically shows raised protein, often exceeding 100 mg/dL, with high fibrinogen content. On standing, fibrin strands form the characteristic spider-web or cobweb clot, and AFB are more readily found within this coagulum than in the supernatant. Glucose is low and chloride may fall below 600 mg/dL, but elevated chloride does not occur. Neutrophil predominance is an early transient finding, not the cause of the web.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.