HOSPITAL ACQUIRED PNEUMONIA

 HOSPITAL ACQUIRED PNEUMONIA


Hospital-Acquired Pneumonia (HAP), also known as nosocomial pneumonia, refers to pneumonia that occurs 48 hours or more after admission to a hospital, which was not incubating at the time of admission. It is one of the most common nosocomial infections and is associated with significant morbidity and mortality.

Key Aspects of HAP Definition:

  • Timing: The defining characteristic of HAP is that it develops at least 48 hours after hospital admission. Pneumonia developing earlier than this is generally classified as community-acquired pneumonia (CAP).

Causative Organism

  • HAP and VAP are usually caused by organisms resistant to common antibiotics. Common pathogens include:

    Bacterial Causes:

    • Gram-negative organisms:
      • Pseudomonas aeruginosa: A frequent cause of HAP/VAP, especially in ICU settings.
      • Klebsiella pneumoniae: Often resistant to multiple antibiotics.
      • Escherichia coli
      • Acinetobacter baumannii: Highly resistant and difficult to treat.
    • Gram-positive organisms:
      • Staphylococcus aureus (including MRSA)

  • Risk Factors

    • Mechanical ventilation (VAP—ventilator-associated pneumonia, a subset of HAP).
    • Prolonged hospital stay, especially in intensive care units (ICUs).
    • Immunosuppression, including corticosteroid use.
    • Recent antibiotic use.
    • Invasive procedures like central lines or urinary catheters.

Diagnostic Criteria:

  • Clinical Presentation: Fever, purulent sputum, leukocytosis, and new or worsening infiltrates on chest radiographs after the patient has been in the hospital for more than 48 hours.
  • Microbiological Evidence: Diagnosis is often supported by identifying pathogens through sputum cultures, blood cultures, or bronchoalveolar lavage fluid in ventilated patients.
  • Imaging: Radiological evidence of new or progressive infiltrates on chest X-ray or CT scan.

Clinical Importance:

  • Antibiotic Resistance: HAP is often caused by multidrug-resistant organisms, making its treatment more challenging. Appropriate empirical broad-spectrum antibiotics must be initiated promptly, followed by de-escalation based on microbiological data.
  • Complications: HAP is associated with complications like sepsis, acute respiratory distress syndrome (ARDS), and multi-organ failure.

TREATMENT

1. Antibiotics for Hospital-Acquired Pneumonia (HAP)

Risk Factors for Multidrug-Resistant (MDR) Pathogens Empirical Antibiotics Duration
Low risk of MDR pathogens – Piperacillin-tazobactam (4.5 g IV Q6H) 7 days
– Cefepime (2 g IV Q8H)
High risk of MDR pathogens – Piperacillin-tazobactam + Vancomycin (15 mg/kg IV Q12H) 7-14 days
– Cefepime or Meropenem (1 g IV Q8H) + Vancomycin or Linezolid (600 mg Q12H)
MRSA coverage needed – Add Vancomycin or Linezolid 7-14 days

Note: Empirical coverage for MRSA and Pseudomonas is warranted in patients with risk factors such as prior IV antibiotic use, prolonged hospitalization, or mechanical ventilation.

2. Antibiotics for Ventilator-Associated Pneumonia (VAP)

Organisms Covered Empirical Antibiotics Duration
MDR pathogens (Pseudomonas, Acinetobacter) – Piperacillin-tazobactam + Vancomycin or Linezolid 7-14 days
– Cefepime or Meropenem
MRSA – Add Vancomycin or Linezolid 7-14 days
ESBL-producing organisms – Meropenem or Imipenem-cilastatin 7-14 days

3. Duration of Antibiotic Therapy

  • HAP/VAP: 7-14 days, depending on the clinical response and presence of multidrug-resistant organisms.

4. Antibiotic De-escalation

Once culture results are available, the antibiotic regimen should be narrowed (de-escalation) to target the specific pathogen. This helps prevent antibiotic resistance and minimizes side effects.

5. Management of Complications

  • Pleural effusion/empyema: If pleural fluid is present, thoracentesis or chest tube drainage may be required.
  • Sepsis: Management according to sepsis protocols, including aggressive fluid resuscitation and vasopressors if necessary.
  • Acute respiratory distress syndrome (ARDS): Mechanical ventilation with low tidal volume ventilation and positive end-expiratory pressure (PEEP) may be necessary.

Bibliography

Books

  1. Mandell, L. A., Bennett, J. E., & Dolin, R. (2019). Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases (9th ed.). Elsevier. This textbook provides a detailed overview of the etiology, pathophysiology, and management of pneumonia.

  2. Cunha, B. A. (Ed.). (2010). Pneumonia Essentials. Physicians’ Press. A concise guide focusing on the clinical aspects and treatment of pneumonia in various patient populations.

  3. Murray, J. F., & Nadel, J. A. (2016). Textbook of Respiratory Medicine (6th ed.). Elsevier Saunders. A comprehensive reference covering the respiratory system, including an in-depth section on pneumonia.

Journal Articles

  1. Metlay, J. P., Waterer, G. W., Long, A. C., et al. (2019). “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.” American Journal of Respiratory and Critical Care Medicine, 200(7), e45-e67. DOI: 10.1164/rccm.201908-1581ST. This guideline provides evidence-based recommendations for the diagnosis and treatment of community-acquired pneumonia (CAP).

  2. Torres, A., Niederman, M. S., Chastre, J., et al. (2017). “International ERS/ESICM/ESCMID/ALAT Guidelines for the Management of Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia.” European Respiratory Journal, 50(3), 1700582. DOI: 10.1183/13993003.00582-2017. A comprehensive set of guidelines addressing the management of hospital-acquired and ventilator-associated pneumonia.

  3. Jain, S., Self, W. H., Wunderink, R. G., et al. (2015). “Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults.” New England Journal of Medicine, 373(5), 415-427. DOI: 10.1056/NEJMoa1500245. This study provides a detailed analysis of the incidence and etiology of pneumonia requiring hospitalization in the United States.

Guidelines and Reports

  1. National Institute for Health and Care Excellence (NICE). (2019). “Pneumonia (community-acquired): antimicrobial prescribing.” Available at: https://www.nice.org.uk/guidance/ng138. A set of guidelines from NICE focused on the antimicrobial management of community-acquired pneumonia.

  2. World Health Organization (WHO). (2014). “Revised WHO Classification and Treatment of Pneumonia in Children at Health Facilities: Evidence Summaries.” Available at: https://www.who.int/maternal_child_adolescent/documents/child-pneumonia-treatment/en/. This document outlines WHO recommendations for the treatment of pneumonia in children.

Online Resources

  1. UpToDate. “Overview of Community-Acquired Pneumonia in Adults.” Available at: https://www.uptodate.com/contents/community-acquired-pneumonia-in-adults. A comprehensive resource for clinicians that covers the etiology, diagnosis, and treatment of pneumonia with regularly updated information.

  2. Centers for Disease Control and Prevention (CDC). “Pneumonia.” Available at: https://www.cdc.gov/pneumonia/index.html. A reliable source of information for clinicians and the public on pneumonia, including prevention and treatment strategies.

  3. American Thoracic Society. “Pneumonia and Respiratory Infections.” Available at: https://www.thoracic.org/patients/patient-resources/resources/pneumonia.pdf. An informative guide for patients and healthcare providers on understanding and managing pneumonia.

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