Differences between Nosocomial or Hospital and Community Acquired Pneumonia Adherence to evidence based guidelines for the management of pneumonia in a tertiary teaching hospital in Riyadh ScienceDirect Definitions of Pneumonia Categories Pneumonia Download Table From Common Infection to Critical Threat Pneumonia is a lung infection that can be: Community acquired (CAP) contracted outside healthcare settings Hospital acquired (HAP) develops during a hospital stay Ventilator associated (VAP)