How long after discharge from a hospital is pneumonia considered hospital-acquired pneumonia (HAP)?

Hospital-Acquired Pneumonia After Discharge

Pneumonia occurring within 90 days after hospital discharge should be considered healthcare-associated pneumonia (HCAP), which warrants similar empiric antibiotic coverage as hospital-acquired pneumonia due to the risk of multidrug-resistant organisms. 1

Key Timeframe Definitions

During hospitalization:

• Hospital-acquired pneumonia (HAP) is defined as pneumonia occurring 48 hours or more after hospital admission, which was not incubating at admission 2
• This 48-hour threshold is the standard diagnostic criterion established by the American Thoracic Society 2

After hospital discharge:

• The Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS) define healthcare-associated pneumonia (HCAP) as pneumonia occurring in patients with hospitalization for 2 or more days within the preceding 90 days 1
• This 90-day window after discharge is the critical timeframe during which pneumonia should be treated with consideration for multidrug-resistant organisms 1

Clinical Reasoning for the 90-Day Window

The rationale for this extended timeframe includes:

• Patients with recent hospitalization are at substantially higher risk for multidrug-resistant organisms compared to community-acquired pneumonia patients 1
• Risk factors persist beyond discharge, including previous antibiotic exposure, colonization with resistant pathogens, and healthcare system contact 2
• Duration of hospital stay, particularly prolonged stays over 5 days, increases the risk of colonization with multidrug-resistant pathogens 2

Important Guideline Evolution and Caveats

A critical caveat: The 2016 IDSA/ATS guidelines removed the HCAP category, though some healthcare systems continue to use this classification 1

• The European Respiratory Society guidelines do not emphasize HCAP, noting that European data suggest HCAP patients often have similar etiology to community-acquired pneumonia 1
• The European Respiratory Society recommends individualized risk assessment for multidrug-resistant organisms rather than automatic broad-spectrum coverage based solely on healthcare contact 1

Practical Application

If using the HCAP classification in your practice:

• Patients with hospitalization within 90 days should receive empiric antibiotic coverage for multidrug-resistant organisms, similar to hospital-acquired pneumonia 1
• Consider additional HCAP criteria: residence in nursing home, receipt of IV antibiotics/chemotherapy/wound care within 30 days, or hemodialysis within 30 days 1

Common pathogens to cover:

• Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Acinetobacter species, and antibiotic-resistant Enterobacteriaceae are the primary concerns 2, 3
• These multidrug-resistant organisms are found with similar frequencies in HCAP, HAP, and VAP patients 3