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[Normocellular bacterial meningitis]
1Herning Centralsygehus, medicinsk afdeling.
Abstract:
Bacterial meningitis is usually associated with pleocytosis of the cerebrospinal fluid due to the presence of polymorphonuclear leucocytes. However, 75 cases of bacterial meningitis without pleocytosis have been published. Normocellular bacterial meningitis accounts for 3.5% (1-42%) of all patients suffering from bacterial meningitis and is seen in all age groups: The finding can be explained by three different mechanisms including 1) lumbar puncture performed early in the course of meningitis, 2) immune deficiency, and 3) relative leucopenia due to severe sepsis. Normocellular bacterial meningitis is in general associated with a good prognosis except for cases with severe underlying diseases. A high concentration of bacteria in a normocellular cerebrospinal fluid might also indicate a poor prognosis.
Insights
Bacterial meningitis typically causes cerebrospinal fluid pleocytosis. However, normocellular bacterial meningitis, occurring in 3.5% of cases, presents without this hallmark sign, impacting prognosis.
Area of Science:
- Neurology
- Infectious Diseases
- Clinical Microbiology
Context:
- Bacterial meningitis is a severe infection usually characterized by elevated white blood cells (pleocytosis) in cerebrospinal fluid (CSF).
- A subset of bacterial meningitis cases, termed normocellular bacterial meningitis, lacks this typical CSF pleocytosis.
- This condition represents approximately 3.5% of bacterial meningitis cases across all age groups.
Purpose:
- To review the phenomenon of normocellular bacterial meningitis.
- To explore the underlying mechanisms contributing to the absence of pleocytosis in bacterial meningitis.
- To discuss the prognostic implications of normocellular bacterial meningitis.
Summary:
- Normocellular bacterial meningitis can occur due to early lumbar puncture, immune deficiency, or relative leukopenia from severe sepsis.
- While often associated with a good prognosis, severe underlying conditions or high bacterial loads in normocellular CSF may indicate a poorer outcome.
- This presentation challenges the typical diagnostic markers for bacterial meningitis.
Impact:
- Highlights the importance of considering bacterial meningitis even in the absence of CSF pleocytosis.
- Informs clinical practice regarding the diagnosis and management of atypical meningitis presentations.
- Contributes to understanding the varied host-pathogen interactions in bacterial meningitis.