Pathogenesis and pathology of brain abscess.

ABSTRACT

Brain abscess continues to be a serious medical problem with increasing incidence despite advances in diagnostic and surgical methods, and advent of new antibiotics. This is due to increase in immune suppressed individuals, opportunistic pathogens and resistance to antibiotics. The morbidity, mortality and long term sequelae of brain abscess like cognitive impairment and poor neurological outcome are due to persistent release of proinflammatory mediators by activated microglia, astrocytes and infiltrating inflammatory cells, along with disruption of blood brain barrier. Anti-inflammatory drugs along with specific antimicrobial agents help in minimizing damage to the adjacent brain parenchyma. Identification of microorganisms in the aspirated material or the excised specimen help decide the optimal antimicrobial therapy. Prompt examination of smear and meticulous culture techniques to identify aerobes, anerobes, mycobacteria, actinomycetes, parasites and fungi are of utmost importance in choosing antibiotics. Histology complements culture and plays a key role especially in specific infections. Use of appropriate histochemical stains along with tissue reaction helps in diagnosis. The route of spread, the type and virulence of the organism, thickness of the capsule, location and number of abscesses in the brain, and immune status of the host are important determinants of outcome. Identification of microorganisms and insights into pathogenesis allow appropriate therapeutic interventions to improve outcome.