Let’s Talk About Pneumonia

Pneumonia classification has changed: HCAP is gone, aspiration pneumonia is usually treated like community-acquired pneumonia, and true HAP or VAP requires onset more than 48 hours after admission or intubation. Severity and resistant-pathogen risk now drive empiric therapy more than old labels.

Updated Pneumonia Classification

• HCAP no longer used: Healthcare-associated pneumonia has been eliminated from current guidelines because it pushed too many patients toward unnecessary broad-spectrum therapy without reliably identifying resistant pathogens.
• True HAP and VAP: Hospital-acquired and ventilator-associated pneumonia are defined by new infection developing more than 48 hours after admission or intubation, a timing distinction that changes your starting regimen.
• Aspiration treated as CAP: Aspiration pneumonia remains a real syndrome, but routine anaerobic and gram-negative coverage is no longer recommended for most cases managed as community-acquired pneumonia.
• Severity over old labels: The key fork is now severe versus non-severe pneumonia using IDSA severe CAP criteria rather than legacy categories. We walk through how that changes antibiotic choice in the episode.

Antibiotic and Disposition Decisions

• IDSA severe CAP criteria: Severe pneumonia is defined by either one major criterion such as vasopressor-dependent shock or mechanical ventilation, or at least three minor criteria including multilobar infiltrates and confusion.
• MRSA pseudomonas risk triggers: Empiric anti-MRSA or antipseudomonal therapy is reserved for severe disease with recent IV antibiotics or for patients with proven prior MRSA or Pseudomonas pneumonia within the last year.
• Outpatient CAP options: Ambulatory community-acquired pneumonia treatment remains familiar, with doxycycline, amoxicillin, azithromycin, or a respiratory fluoroquinolone as the main first-line options.
• Oral therapy for inpatients: For many hospitalized CAP patients, oral antibiotics are as effective as parenteral therapy and can reduce cost and hospital length of stay. We get into the practical switching mindset in the chapter.
• Fewer broad-spectrum starts: The net effect of the guideline update is fewer patients receiving empiric broad-spectrum coverage up front, while still protecting those with clear resistant-pathogen risk.

References

1. Metlay JP, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67.  PMID: 31573350 
2. Cunha BA, et al. Pharmacodynamics of doxycycline. Clin Microbiol Infect. 2000;6(5):270-273. PMID: 1168126
3. Dean N, et al. “Diagnosis and Management of Community-Acquired Pneumonia (CAP).” Intermountain Healthcare Care Process Models. Update published online June 2014 at https://intermountainhealthcare.org/ext/Dcmnt?ncid=520102603 
4. Gattarello S. What Is New in Antibiotic Therapy in Community-Acquired Pneumonia? An Evidence-Based Approach Focusing on Combined Therapy. Curr Infect Dis Rep. 2015;17(10):501. PMID:26298707
5. Ramirez JA, et al. Early switch from intravenous to oral cephalosporins in the treatment of hospitalized patients with community-acquired pneumonia. Arch Intern Med. 1995;155(12):1273-1276. PMID:7778957
6. Oosterheert JJ, et al. Effectiveness of early switch from intravenous to oral antibiotics in severe community acquired pneumonia: multicentre randomised trial. BMJ. 2006;333(7580):1193. PMID:17090560