What is the definition of Hospital-Acquired Pneumonia (HAP)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: February 24, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Hospital-acquired pneumonia (HAP) is defined as a lung infection that develops 48 hours or more after hospital admission and was not incubating at the time of admission. This definition is based on the most recent and highest quality study available, which emphasizes the importance of distinguishing HAP from community-acquired pneumonia and ventilator-associated pneumonia 1.

Key Characteristics of HAP

  • Develops 48 hours or more after hospital admission
  • Was not incubating at the time of admission
  • Typically involves different pathogens and carries a higher risk of antibiotic resistance compared to community-acquired pneumonia
  • A subset of HAP is ventilator-associated pneumonia, which occurs in patients on mechanical ventilation

Common Causative Organisms

  • Staphylococcus aureus
  • Pseudomonas aeruginosa
  • Other gram-negative bacteria

Impact on Patients

  • Significant cause of morbidity and mortality in hospitalized patients
  • Often leads to prolonged hospital stays and increased healthcare costs
  • Associated with increased duration of mechanical ventilation and ICU and hospital length-of-stay 1

Importance of Accurate Diagnosis and Treatment

  • Prompt and adequate treatment is crucial to reduce mortality and morbidity
  • Accurate diagnosis and treatment can help reduce the risk of antibiotic resistance and improve patient outcomes 1
  • Healthcare professionals should be aware of the latest guidelines and recommendations for the management of HAP, including the use of antimicrobial therapy and preventive measures 1

From the Research

Definition of Hospital-Acquired Pneumonia (HAP)

  • Hospital-acquired pneumonia (HAP) is defined as radiologically confirmed pneumonia occurring ≥48h after hospitalization, in non-intubated patients 2
  • HAP is also defined as an infection of lung parenchyma that was neither present nor incubating at the time of the patient's admission to the hospital 3
  • Pneumonia that occurs 48 hours or more after admission is considered HAP 4

Key Characteristics of HAP

  • HAP is one of the most commonly encountered nosocomial infections 5
  • Patients who develop severe HAP experience considerable morbidity and mortality, and the condition results in a substantial expenditure of health care resources 5
  • HAP can be caused by various pathogens, including Gram-negative bacilli and Staphylococcus aureus 2

Diagnosis and Treatment of HAP

  • Empirical treatment regimens for HAP use broad-spectrum antimicrobials 2
  • Radiologically confirmed HAP is associated with higher levels of inflammatory markers and sputum culture positivity 2
  • Pharmacist intervention can contribute to reducing inflammation in the early phase and shortening the duration of antimicrobial therapy for severe HAP 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Hospital-acquired pneumonia: perspectives for the healthcare epidemiologist.

Infection control and hospital epidemiology, 1997

Research

[Effects of early pharmacist intervention on antimicrobial therapy for severe hospital-acquired pneumonia].

Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan, 2013

Research

Severe hospital-acquired pneumonia: a review for clinicians.

Current infectious disease reports, 2009

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.