Introduction

The purpose of this chapter is to provide a brief synopsis of bacterial meningitis and brain abscess and the animal models used to study these diseases and evaluate potential therapeutic modalities. The reader is encouraged to consult the selected references for more detailed information.

Bacterial meningitis

Despite advances made in vaccination and treatment strategies, bacterial meningitis remains associated with a significant mortality rate and incidence of neurological sequelae, particularly in very young and elderly patients. Approximately 1.2 million cases of bacterial meningitis are estimated to occur worldwide annually with 135 000 deaths. Long-term effects resulting from meningitis include hearing loss, hydrocephalus, and sequelae associated with parenchymal brain damage including memory loss, cerebral palsy, learning disabilities, and seizures. Organisms that colonize the mucosal membranes of the nasopharynx include Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae which are the leading etiologic agents of community-acquired meningitis. Recurring bacterial meningitis epidemics, the emergence of antimicrobial resistance among many meningeal pathogens, and the failure to introduce the H. influenzae conjugate vaccines (Hib) into many developing countries all contribute to bacterial meningitis remaining a serious global health problem.

Bacterial meningitis elicits a complex myriad of pathophysiological changes that present numerous obstacles when considering the design of therapeutic strategies. For example, besides the direct damage induced by pathogens, the host antibacterial response elicited during the acute phase of bacterial meningitis can be detrimental to neurons and other glia in the central nervous system (CNS) due to the toxic effects of cytokines, chemokines, proteolytic enzymes, and oxidants produced locally at the site of infection.