Duration of therapy Most cases of bacterial meningitis should be treated for a period of 10 to 14 days except when there is a persistent parameningeal focus of infection (otitic or sinus origin), in which cases longer treatment may be needed. Antibiotics should be administered in full doses parenterally (preferably intravenously) throughout the period of treatment. Treatment failures with certain drugs, notably ampicillin, may be attributable to oral or intramuscular administration, resulting in inadequate concentrations in the CSF. Repeated lumbar punctures are not necessary to assess the effects of therapy as long as there is progressive clinical improvement. The CSF glucose may remain low for many days after other signs of infection have subsided and should occasion concern only if bacteria are present in the fluid and the patient remains febrile and ill.
Persistence of fever or the late appearance of drowsiness, hemiparesis, or seizures should raise the suspicion of subdural effusion, mastoiditis, venous sinus thrombosis, cortical vein or jugular phlebitis, or brain abscess; all require that therapy be continued for a longer period. Bacteriologic relapse after treatment is discontinued requires reinstitution of therapy and exploration for a persistent parameningeal focus of infection, such as in the spinal column.
Corticosteroids Controlled studies several decades ago were unable to demonstrate beneficial effects of corticosteroids in the treatment of bacterial meningitis. More recent studies have given another perspective of the therapeutic value of dexamethasone in children and adults with meningitis. In children, although mortality was not affected in the main study conducted by Lebel and colleagues, fever subsided more rapidly and the incidence of sensorineural deafness and other neurologic sequelae was reduced, particularly in those children with H. influenzae meningitis. On these grounds, it has been recommended that the treatment of childhood meningitis include dexamethasone in high doses (0.15 mg/kg qid for 4 days), instituted as soon as possible.
Despite conflicting results from earlier studies of corticosteroids in adults, the trial by deGans and van de Beck has demonstrated a reduction in mortality and improved overall outcome if dexamethasone 10 mg is given just before the first dose of antibiotics and then repeated q6h for 4 days. The improvement was largely in patients who were infected with pneumococcus. Seizures and coma were reduced in incidence as a result of the administration of corticosteroids, but neurologic sequelae, such as hearing loss, were not affected. Based on a number of smaller studies, authorities in the field of bacterial meningitis have endorsed the administration of dexamethasone in the doses mentioned above, particularly if they can be started before antibiotics, and in those with presumed pneumococcal infection in developed countries (see
Tunkel and Scheld). They also, however, have advised against the use of the drug if there is septic shock.
In developing countries, especially those with high rates of HIV, the benefits of adjuvant dexamethasone have not been clear. Improved survival was limited to those who ultimately had bacteria isolated from the CSF, in contrast to those with suspected meningitis but negative cultures. Nevertheless, the incidence of deafness was reduced (Nguyen et al; Scarborough et al).