Acute nosocomial pneumonia is broadly defined as pneumonia characterized by a new and persistent infiltrate (radiographically present for greater than 48 hours) PLUS one of the following:
The Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) recently reviewed risk factors and developed objective major and minor criteria to identify patients who require direct admission to an Intensive Care Unit (ICU). The most up-to-date definitions use need for invasive mechanical ventilation or septic shock, requiring vasopressors, as absolute indicators for direct admission to an ICU. For patients who do not meet either of these two major criteria, minor criteria have been proposed that are based on CURB-65 and ATS criteria with new additions. For admission to an ICU or high level unit, patients must fulfill at least three of these minor criteria.
CURB and CRB-65 scores can be used in the hospital and out-patients setting to assess pneumonia severity and the risk of death.