Dexamethasone in the treatment of experimental Haemophilus influenzae type b meningitis

A model of experimental lapin meningitis was used to assess the effect of meningeal inflammation caused by Haemophilus influenzae type b on development of brain edema, increase in intracranial pressure, and production of brain lactate. Four treatments were assessed: (1) dexamethasone alone, (2) dexamethasone plus ceftriaxone, (3) ceftriaxone alone, and (4) no treatment. The brain water content in untreated rabbits with meningitis was 419 ± 10 g of H₂O/100g of dry weight after 29 hr of infection (vs. 405 ± 14 in uninfected rabbits; P < .05). In rabbits treated with dexamethasone, ceftriaxone, or both, these values were 404 ± 12, 406 ± 12, and 411 ± 14 g, respectively (P > .05). The cerebrospinal fluid (CSF) pressure and lactate levels were significantly increased in all animals during the 24 hr of meningeal inflammation (P < .005), and these levels were comparably reduced after 9 hr of treatment. Although the values for brain water content, CSF pressure, and lactate concentrations in infected animals treated with ceftriaxone plus dexamethasone were not significantly different from those in animals treated with ceftriaxone alone, the values were consistently lower in the former group.