This retrospective pilot study seeks to characterize cerebrospinal fluid profiles (CSF) of immunocompetent versus immunocompromised patients with confirmed infectious meningitis/encephalitis.  

There are widely accepted ranges of typical CSF values used to guide diagnosis and treatment of suspected infectious meningitis/encephalitis in healthy individuals. However, it is unclear whether these values should routinely be applied to immunocompromised patients. Atypical CSF profiles may impact timely diagnostics, treatment, and clinical outcomes.  

A retrospective database of patients with confirmed infectious bacterial or viral meningitis/encephalitis, admitted between 2010-2021, was constructed. Patients ≥18 years old, identified via ICD-9/10 codes for infectious meningitis/encephalitis were included. Demographic data, serum, CSF, imaging, and clinical data including immune status were collected.  

Of 65 definitive bacterial meningitis/encephalitis cases, 42 patients were immunocompromised.  Immunocompromised patients had a mean adjusted CSF WBC count of 2366 cells/μL ± 537 with 91.9 ± 20.9% neutrophils, CSF protein of 241.5 mg/dL ± 32.7, and glucose ratio of 0.33 ± 0.05. Immunocompetent patients had a mean CSF WBC count of 3323 cells/μL ± 1244 with 75.7% ± 6.5% neutrophils, CSF protein of 321.4 mg/dL ± 61.4, and glucose ratio of 0.32 ± 0.06. There were 62 definitive viral meningitis/encephalitis cases. 32 patients were immunocompromised, with a mean CSF WBC count of 73.6 cells/μL ± 17.0 with 63.7% ± 3.9% lymphocytes, CSF protein of 115.8 mg/dL ± 23.2, and glucose ratio of 0.49 ± 0.02. Immunocompetent patients had a mean CSF WBC count of 468 cells/μL ± 81.8 (p<0.05) with 72.6% ± 3.6% lymphocytes, CSF protein of 105.2 mg/dL ± 6.4, and glucose ratio of 0.51 ± 0.01. 

This study suggests that immunocompromised patients with infectious meningitis/encephalitis may have differing, atypical CSF profiles; this may impact timely diagnosis and clinical course. Multi-site collaboration with pooling of retrospective databases to increase generalizability of findings and validate this hypothesis is pending.