II. Epidural and Subdrual Abscess or Empyema
Abscesses are localized collections of pus. Pyogenic organisms are the infectious agent involved with abscess formation. Empyema describes the accumulation of pus within a space or cavity, again, typically secondary to pyogenic organism infection. Epidural and subdural infections can be called either abscess or empyema. Pathogenesis involves direct inoculation or spread from nearby infections. Etiologic agents are usually bacteria; streptococcus and staphylococcus are the most common.