Establishment of rat pneumococcal meningitis models: a histopathological analysis

The aim of this study was to perform a preliminary investigation of the pathogenesis of bacterial meningitis-induced brain injury by establishing rat pneumococcal meningitis models. Infant Wistar rats were intracranially inoculated with different concentrations of Streptococcus pneumoniae. Rats were sacrificed at different time points to observe clinical symptoms and pathological changes in brain tissues. Twenty-four hours after intracranial inoculation with Streptococcus pneumoniae, regardless of high or low concentrations of bacterial inoculation, all rats developed bacterial meningitis with manifestations such as lethargy and seizures. Pathological changes in brain tissues included subarachnoid and intraventricular inflammation, vasodilation and vascular congestion, and cortical neuronal necrosis. The number of rats with seizures, the degree of cerebral vascular disease, and the extent of neuronal damage were associated with the concentration of bacterial inoculum. Thirty days after infection, brain tissue weight significantly reduced. The pathological changes induced by inoculation with pneumococcal meningitis in Wistar rats were similar to those seen in the human brain. The possible mechanisms of brain damage caused by meningitis are cerebrovascular inflammation and disruption of regional cerebral blood flow.