Complications and treatment of bacterial meningitis

Abstract

The prognosis of bacterial (purulent) meningitis depends on early diagnosis and prompt initiation of antibiotic therapy. However, despite the improvement of antimicrobial therapy during the last decades, mortality rate and sequelae due to bacterial meningitis remain unacceptably high. For example, the mortality rate of meningitis due to Streptococcus pneumoniae, the organism most often responsible for bacterial meningitis in adults, has remained relatively unchanged during the last decades and is still as high as 20-30%. The unfavourable courses of bacterial meningitis are often due to intracranial complications including brain oedema, cerebrovascular arterial or venous involvement, and hydrocephalus. These complications usually lead to an increased intracranial pressure. Patients with bacterial meningitis may require adjunctive therapy including administration of hyperosmolar agents, hyperventilation or ventricular drainage. Anticoagulation with doseadjusted intravenous heparin should be considered in patients with meningitis-associated septic venous sinus thrombosis proven by MRI, MR angiography or cerebral angiography. Recently, a prospective, randomised, multicentre, double-blind trial (performed by de Gans and van de Beek) in adults with acute bacterial meningitis showed a beneficial effect of dexamethasone (10 mg was administered 15 to 20 minutes before or with the first dose of antibiotic and was given every 6 hours for 4 days) compared with placebo. Treatment with dexamethasone was associated with a significant reduction in the risk of an unfavourable outcome, and a significant reduction in mortality. Among the patients with pneumococcal meningitis, 14% of the dexamethasone group died, as compared with 34% of the placebo group. Gastrointestinal bleeding occurred in 2 patients of the dexamethasone group and in 5 patients of the placebo group. Based on these data the use of dexamethasone is recommended in adult patients with suspected bacterial meningitis, i.e. in patients with clinical suspicion plus cloudy cerebrospinal fluid, detection of bacteria in the cerebrospinal fluid (CSF) by microscopy of a Gram's stained smear or a CSF cell count of more than 1000 cells/μl.