Bacterial Meningitis Diagnosis and Management

Diagnosis of Streptococcus pneumoniae Meningitis

The American College of Physicians and Infectious Diseases Society of America recommend that Streptococcus pneumoniae is the most common cause of community-acquired bacterial meningitis in adults, accounting for the majority of cases in immunocompetent patients 1, 2
Patients with pneumococcal meningitis are more likely to present with seizures, focal neurological symptoms, and reduced consciousness compared to other bacterial causes, according to the Infectious Diseases Society of America 2, 4
The Centers for Disease Control and Prevention guidelines state that a CSF/blood glucose ratio of 0.27 is highly predictive of bacterial meningitis, although the optimal cutoff is 0.36 with 92.9% sensitivity and specificity for bacterial meningitis 1, 2
The presence of polymorphonucleocyte predominance is characteristic of acute bacterial meningitis, as stated by the Clinical Microbiology and Infection guidelines 1, 2
Elevated protein (62 mg/dL) and elevated opening pressure (27 cm H2O) further support bacterial etiology, according to the Clinical Microbiology and Infection guidelines 1, 2

Cryptococcus neoformans typically presents with lymphocytic predominance, not polymorphonucleocytes, and is more common in immunocompromised patients, as stated by the MMWR Recommendations and Reports 5
Herpes Simplex Virus causes lymphocytic pleocytosis, not neutrophilic, and CSF glucose is typically normal or only mildly decreased, according to the Clinical Microbiology and Infection guidelines 1, 2
Mycobacterium tuberculosis presents with lymphocytic predominance in CSF, more subacute/chronic presentation, and CSF glucose is low but protein is typically markedly elevated, as stated by the MMWR Recommendations and Reports 5

The Infectious Diseases Society of America recommends that the empiric antibiotic regimen of ceftriaxone plus vancomycin should be initiated to cover S. pneumoniae including penicillin-resistant strains 1
The addition of corticosteroids (dexamethasone) is recommended for suspected pneumococcal meningitis to reduce mortality and neurological sequelae, according to the Clinical Microbiology and Infection guidelines 1
The American College of Emergency Physicians states that treatment should begin within 1 hour of presentation, and normal CSF parameters do not rule out bacterial meningitis in immunocompromised patients 1, 3