[New developments in the diagnosis and therapy of acute bacterial meningitis].

BACKGROUND: Acute bacterial meningitis is a medical emergency. Despite advances in the diagnosis and treatment it continues to have a high case-fatality rate and high rates of long-term neurologic sequelae. ETIOLOGY: Since the widespread use of the vaccine for Haemophilus influenzae type B, Streptococcus pneumoniae has replaced it as the most common cause of acute community-acquired bacterial meningitis in industrialized countries. The rising incidence of beta-lactam-resistant pneumococci has to be considered when choosing a regimen for empiric antibiotic therapy. DIAGNOSIS: The clinical diagnosis remains difficult, as absent clinical meningeal signs do not exclude bacterial meningitis. If bacterial meningitis is considered a possible diagnosis, empiric antibiotic therapy should be initiated without any delay. Prior blood cultures and, if not contraindicated, a lumbar puncture should be performed. Based on new evidence, a screening cranial computed tomography to rule out raised intracranial pressure prior to lumbar puncture is recommended only for patients with defined risk factors (age > 60 years; preexisting immunodeficiency, immunosuppression, or neurologic diseases; recent seizures; any pathologic finding in the neurologic examination other than meningism). TREATMENT: Empiric antibiotic therapy should be initiated before cranial computed tomography. Adjuvant dexamethasone therapy initiated with or prior to the antibiotic therapy reduces mortality and morbidity for patients with pneumococcal meningitis without increasing the rate of side effects.