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Bacterial meningitis in the absence of CSF pleocytosis
Abstract:
Two cases of acute bacterial meningitis occurred with an absent CSF WBC response. To determine the incidence and clinical characteristics of such patients, 50 consecutive cases of meningitis were reviewed retrospectively. In addition to the two initially noted cases, five additional cases were found. In the seven cases, there were six or fewer cells, but bacteria were detected in the CSF. A distinctive clinical and laboratory syndrome emerged. All seven patients were either old or had Hodgkin's disease or severe alcoholism. All patients had evidence of an overwhelming infection with confusion or nuchal rigidity. As compared with the remaining 45 patients with meningitis and CSF pleocytosis, no fever (less than 38 degrees C), a lower peripheral WBC count, and near-normal CSF glucose and protein concentrations were common. Organisms involved were EScherichia coli in three patients, Pneumococcus in three patients, and mixed anaerobes in patient. A fatal outcome ensued in six of seven patients. Despite the correct choice of an antibacterial agent, doses were late and suboptimal for meningitis. This syndrome is surprisingly common in host-defective cases, has an ominous prognosis, and must be treated expectantly with antimicrobial agents that enter the CSF.
Insights
Bacterial meningitis can occur without a cerebrospinal fluid (CSF) white blood cell (WBC) response, particularly in immunocompromised patients. This rare presentation has a poor prognosis and requires prompt, CSF-penetrating antimicrobial treatment.
Area of Science:
- Infectious Diseases
- Neurology
- Immunology
Background:
- Bacterial meningitis typically elicits a significant cerebrospinal fluid (CSF) white blood cell (WBC) response.
- An absent or blunted CSF WBC count in bacterial meningitis is unusual and may indicate a specific patient subgroup.
Purpose of the Study:
- To determine the incidence and clinical characteristics of bacterial meningitis cases presenting with an absent CSF WBC response.
- To identify associated risk factors and clinical syndromes in this patient population.
Main Methods:
- Retrospective review of 50 consecutive meningitis cases.
- Analysis of clinical and laboratory data, including CSF analysis, patient demographics, and comorbidities.
Main Results:
- Seven cases (14%) of bacterial meningitis with absent/low CSF WBC (<6 cells/mL) and positive CSF bacterial culture were identified.
- Patients were elderly or had significant comorbidities (Hodgkin's disease, alcoholism).
- Common features included confusion, nuchal rigidity, absence of fever, lower peripheral WBC, and near-normal CSF glucose/protein.
Conclusions:
- Bacterial meningitis with an absent CSF WBC response is a distinct syndrome often seen in immunocompromised hosts.
- This presentation is associated with overwhelming infection, a high fatality rate (6/7 patients), and requires aggressive, CSF-penetrating antimicrobial therapy.
- Early and appropriate antimicrobial dosing is crucial, despite the challenging diagnostic presentation.