What is the difference between viral meningitis and bacterial meningitis?

From the Guidelines

Bacterial meningitis requires immediate empiric antibiotic therapy, whereas viral meningitis is often self-limiting and requires only supportive care. The distinction between viral and bacterial meningitis is crucial due to the significant differences in their treatment and outcomes. Viral meningitis, typically caused by enteroviruses, herpes viruses, or arboviruses, presents with fever, headache, neck stiffness, and photophobia, but patients generally appear less toxic than those with bacterial meningitis 1. In contrast, bacterial meningitis, caused by bacteria such as Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae, is a medical emergency that presents with similar symptoms but often more severe, with altered mental status, seizures, and focal neurological deficits.

Key differences in treatment approaches include:

• Viral meningitis: supportive care with rest, fluids, and pain management, and specific antivirals like acyclovir for herpes infections
• Bacterial meningitis: immediate empiric antibiotic therapy, typically with a combination of vancomycin and a third-generation cephalosporin, adjusted based on culture results, and potential use of dexamethasone to reduce inflammation 1

Lumbar puncture findings are essential in distinguishing between the two types of meningitis:

• Viral meningitis: clear CSF with lymphocytic predominance, normal glucose, and mildly elevated protein
• Bacterial meningitis: cloudy CSF with neutrophilic predominance, low glucose, and markedly elevated protein

Given the high mortality rate of bacterial meningitis (10-30%) and the rarity of death from viral meningitis, rapid diagnosis and treatment of bacterial meningitis is crucial. Clinicians should rely on their judgment to estimate the risk of bacterial meningitis and initiate empiric antibiotic and adjunctive therapy as needed, rather than solely relying on diagnostic algorithms 1.

From the Research

Viral vs Bacterial Meningitis

• The key difference between viral and bacterial meningitis lies in their causative agents and the severity of the disease.
• Bacterial meningitis is a medical emergency that requires prompt treatment with antibiotics, as seen in studies 2, 3, 4, 5.
• The use of empiric vancomycin plus a third-generation cephalosporin for suspected bacterial meningitis has been recommended since 1997 2.
• Ceftriaxone has been shown to be effective in the treatment of bacterial meningitis, with studies comparing it to combinations of ampicillin and chloramphenicol 3, 4.
• The diagnosis and management of meningitis in adults require a sound understanding of the priorities of managing a patient with suspected meningitis during the first hour, including obtaining blood cultures, performing lumbar puncture, and initiating appropriate therapy 5.
• Guidelines for the treatment of bacterial meningitis vary internationally, with some recommending the use of vancomycin and ceftriaxone for all patients, while others recommend adding vancomycin only for patients with certain risk factors 5.
• The Infectious Diseases Society of America has published guidelines for the management of healthcare-associated ventriculitis and meningitis, which include recommendations for diagnosis, treatment, and prevention 6.

Treatment Options

• Ceftriaxone is a commonly used antibiotic for the treatment of bacterial meningitis, with a once-daily schedule that is more convenient and saves nursing time and expense 3, 4.
• Vancomycin is recommended as part of empiric therapy for suspected bacterial meningitis, particularly for patients with risk factors for pneumococcal meningitis or reduced susceptibility to ceftriaxone 2, 5.
• Dexamethasone is recommended as a routine component of empirical therapy for bacterial meningitis due to its proven role in reducing morbidity and mortality from pneumococcal meningitis 5.

Diagnosis and Management

• The interpretation of cerebrospinal fluid parameters remains a vital skill for clinicians in the diagnosis and management of meningitis 5.
• Blood cultures and lumbar puncture are essential components of the diagnostic workup for suspected meningitis 5.
• Prompt initiation of appropriate therapy is critical in the management of bacterial meningitis, with delays in treatment potentially leading to harmful outcomes 5.