Cerebrospinal Fluid Characteristics in Meningitis

Bacterial Meningitis CSF Characteristics

The typical cerebrospinal fluid picture in bacterial meningitis includes pleocytosis with predominantly polymorphonuclear leukocytes, low glucose concentration, low CSF-to-blood glucose ratio, elevated protein levels, and elevated white blood cell count, according to the American College of Critical Care Medicine 1, 2
CSF typically shows pleocytosis with predominantly polymorphonuclear leukocytes, as recommended by the Infectious Diseases Society of America 1, 3
CSF glucose is markedly decreased, with typical values around low glucose levels, as stated by the American College of Critical Care Medicine 1, 2
CSF-to-blood glucose ratio is typically low, around a low ratio, as reported by the American College of Critical Care Medicine 1, 2
CSF protein is elevated, with concentrations around high protein levels, according to the American College of Critical Care Medicine 1, 2
White blood cell count is elevated, typically around high white blood cell count with neutrophil predominance, as stated by the American College of Critical Care Medicine 1, 2
CSF lactate is often elevated and has better diagnostic accuracy than CSF white blood cell count in differentiating bacterial from other types of meningitis, as recommended by the European Society of Clinical Microbiology and Infectious Diseases 3

Streptococcus pneumoniae meningitis typically presents with more pronounced CSF abnormalities, according to the European Society of Clinical Microbiology and Infectious Diseases 3
Listeria monocytogenes meningitis may not show typical CSF abnormalities in up to a percentage of cases, as reported by the European Society of Clinical Microbiology and Infectious Diseases 3
In pneumococcal meningitis, only a percentage of patients have CSF WBC counts less than a certain threshold, and a percentage have less than a certain threshold, according to the European Society of Clinical Microbiology and Infectious Diseases 3

In neonates with bacterial meningitis, CSF abnormalities may be absent in up to a percentage of cases, as stated by the European Society of Clinical Microbiology and Infectious Diseases 3
In a large cohort of neonates with culture-proven meningitis, a percentage had fewer than a certain threshold WBC/mm³ in the CSF, according to the European Society of Clinical Microbiology and Infectious Diseases 3
For neonates with culture-proven meningitis, CSF WBC counts greater than a certain threshold had a sensitivity and specificity of certain percentages, as reported by the European Society of Clinical Microbiology and Infectious Diseases 3
In immunocompromised patients, normal CSF parameters do not rule out meningitis, and a high index of suspicion should be maintained until cultures are final, according to the American College of Critical Care Medicine 1, 2

The CSF leukocyte count is the best diagnostic parameter for differentiating bacterial meningitis from other diagnoses, with an area under the curve of a certain value in receiver operating characteristic analysis, as stated by the European Society of Clinical Microbiology and Infectious Diseases 4, 5
In immunologically normal hosts, the presence of normal opening pressure, less than a certain threshold white blood cells/μL, and normal CSF protein concentration essentially excludes meningitis, according to the American College of Critical Care Medicine 1, 2

Prior antibiotic treatment may modify CSF findings, though one study suggested CSF WBC count may not be greatly affected by antibiotics given before lumbar puncture, as reported by the European Society of Clinical Microbiology and Infectious Diseases 3
If bacterial meningitis is suspected and lumbar puncture is delayed for any reason, empirical antibiotic therapy should be started immediately after blood cultures are obtained, according to the American College of Critical Care Medicine 1, 2
No single CSF test is fully reliable in distinguishing bacterial meningitis from other forms of meningitis, and results should be interpreted in the clinical context, as stated by the Infectious Diseases Society of America 6

Multiple diagnostic algorithms have been developed to help differentiate between bacterial and viral meningitis, but none are 100% sensitive, as stated by the Clinical Microbiology and Infection guideline society 7