Investigations

Consider CSF for PCR for meningococcus ^b or viruses ^c

Why?

PCR of cerebrospinal fluid can help diagnose meningococcal meningitis

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	LR- (95% CI)
undergoing lumbar puncture b	meningococcal meningitis (CSF culture or microscopy)	PCR	9.7 (3.7 to 25)	0.10 (0.015 to 0.65)

 

Viral PCR can help diagnose viral meningitis

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected meningitis c (pre-test probability: 7.5%)	viral meningitis (viral load in culture media and clinical corroboration)	viral PCR	- (240 to infinity)	100%	0.01 (0.00 to 0.05)	0%