Diagnosis, initial management, and prevention of meningitis.

Although the annual incidence of bacterial meningitis in the United States is declining, it remains a medical emer- gency with a potential for high morbidity and mortality. Clinical signs and symptoms are unreliable in distinguishing bacterial meningitis from the more common forms of aseptic meningitis; therefore, a lumbar puncture with cerebro- spinal fluid analysis is recommended. Empiric antimicrobial therapy based on age and risk factors must be started promptly in patients with bacterial meningitis. Empiric therapy should not be delayed, even if a lumbar puncture cannot be performed because results of a computed tomography scan are pending or because the patient is awaiting transfer. Concomitant therapy with dexamethasone initiated before or at the time of antimicrobial therapy has been demonstrated to improve morbidity and mortality in adults with Streptococcus pneumoniae infection. Within the United States, almost 30 percent of strains of pneumococci, the most common etiologic agent of bacterial meningitis, are not susceptible to penicillin. Among adults in developed countries, the mortality rate from bacterial meningitis is 21 percent. However, the use of conjugate vaccines has reduced the incidence of bacterial meningitis in children and adults.