Procalcitonin in Diagnosing Bacterial Meningitis

Diagnostic Value of Procalcitonin

Procalcitonin is a valuable biomarker for differentiating bacterial from viral meningitis, with high sensitivity and specificity when using appropriate cutoff values, as recommended by the Infectious Diseases Society of America 1, 2
Serum procalcitonin levels are significantly elevated in bacterial meningitis compared to viral meningitis, making it a useful diagnostic marker, according to the Clinical Infectious Diseases guidelines 3, 2
In children with meningitis, using a cutoff of 15.0 mg/L, procalcitonin has shown 94% sensitivity and 100% specificity for diagnosing bacterial meningitis, as reported by the Pediatric Infectious Diseases Society 2
In adults, serum procalcitonin concentrations >10.2 ng/mL have demonstrated sensitivity and specificity of up to 100% for the diagnosis of bacterial meningitis, as stated by the Infectious Diseases Society of America 3, 2

While CSF lactate has good sensitivity and specificity for differentiating bacterial from aseptic meningitis, its value is limited in patients who received antibiotic pretreatment, according to the European Society of Clinical Microbiology and Infectious Diseases 4

Despite its high diagnostic value, procalcitonin should not be used in isolation to determine whether an individual patient should receive antimicrobial therapy, as recommended by the Infectious Diseases Society of America 2, 5
False-negative results have been reported (sensitivity as low as 69% in some studies), as noted by the Clinical Infectious Diseases guidelines 3
Other conditions can cause elevated procalcitonin levels, including severe inflammatory states of non-infectious origin, cerebral hypoxia/ischemia, and trauma, as reported by the American College of Emergency Physicians 6

Obtain blood cultures before starting antibiotics, as they may be positive in 40-90% of bacterial meningitis cases depending on the pathogen, as recommended by the European Society of Clinical Microbiology and Infectious Diseases 7
Do not delay antibiotic treatment while waiting for procalcitonin results; treatment should be initiated within one hour of presentation in suspected bacterial meningitis, as stated by the Infectious Diseases Society of America 1
Consider procalcitonin testing as an adjunct to standard CSF analysis (cell count, protein, glucose) and microbiological tests (Gram stain, culture), as recommended by the Clinical Microbiology and Infection guidelines 1, 7