This study was done to evaluate the efficacy of anti-tumor necrosis factor alpha (anti-TNF-alpha) antibody as an adjunctive therapy in neonatal bacterial meningitis. Newborn piglets were divided into three groups: 8 in the control group, 13 in the meningitis group (MG), and 10 in the meningitis with anti-TNF-alpha antibody group (AG). Meningitis was induced by intracisternal injection of 10(8) colony-forming units of Escherichia coli in 100 microl of saline. In the AG, 200 microl of anti-TNF-alpha antibody was also given intracisternally. In the AG, the elevated cerebrospinal fluid TNF-alpha level observed in the MG was completely abolished, and increased intracranial pressure, hypoglycorrhachia, and CSF pleocytosis observed in the MG were downmodulated. But blood, brain, and CSF lactate levels remained elevated in both MG and AG. Increased brain cell membrane lipid peroxidation products and decreased Na+,K+-ATPase activity observed in the MG were not attenuated in the AG. These results indicate that anti-TNF-alpha antibody was not particularly effective as an adjunctive therapy in attenuating acute inflammatory responses and ameliorating brain damage in neonatal bacterial meningitis.