Dexamethasone in bacterial meningitis: to use or not to use?
Permanent neurologic disabilities are seen in up to a quarter of survivors of bacterial meningitis despite major improvements in therapy. Experimental studies have demonstrated that most of the pathology in meningitis is mediated by inflammatory cytokines such as tumor necrosis factor (TNF) and interleukin-1 (IL-1), which are produced by host cells in response to bacterial invasion of the meninges. Dexamethasone has been used in a number of clinical trials to moderate the host response and to improve neurologic outcome of meningitis. Results of six randomized, placebo controlled trials are summarized in this review. Dexamethasone treatment did not lower mortality. Only a moderate, but not a significant reduction in the neurologic and audiologic sequelae was seen in dexamethasone recipients when Haemophilus influenzae type b (Hib) was the causative agent of meningitis. Following routine use of Hib vaccine, meningitis caused by this agent has virtually disappeared in the USA. Hence, findings from these trials may no longer be applicable in countries with high rates of immunization against Hib. Presently, there is little or no evidence showing a benefit of dexamethasone therapy in meningitis caused by S. pneumoniae or N. meningitidis. Global emergence of penicillin and cephalosporin resistant S. pneumoniae has raised new concerns about the use of dexamethasone in pneumococcal meningitis. Since dexamethasone significantly decreases the penetration and concentration of vancomycin and ceftriaxone in the CSF and delays CSF sterilization, adjunctive dexamethasone therapy may increase the risk of treatment failure in meningitis caused by antibiotic resistant pneumococci. An antibiotic combination should be used in the treatment of meningitis caused by antibiotic resistant pneumococci, particularly if dexamethasone is also being administered concurrently.