Hospital-Acquired Pneumonia - Ventilator-Associated Pneumonia

Patients with hospital-acquired pneumonia (HAP) are those who develop pneumonia 48 hours or more after hospital admission. Ventilator-associated pneumonia (VAP) is defined as the development of pneumonia after 48 hours of mechanical ventilation. Both conditions are associated with significant morbidity and mortality and create a substantial economic burden.

Healthcare-associated pneumonia (HCAP) is no longer categorized with HAP/VAP, based on the Infectious Diseases Society of America and the American Thoracic Society (IDSA/ATS) guidelines and the closer association between HAP/VAP and multidrug resistant (MDR) pathogens.

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Hospital-acquired pneumonia (HAP)
    • New infiltrate on chest x-ray in hospitalized patient
    • New fever with cough
  • Ventilator-associated pneumonia (VAP)
    • New deterioration in mechanically-ventilated patient

Criteria for Diagnosis

  • Pneumonia
    • Presence of new infiltrate plus clinical evidence that infiltrate is of infectious origin, which includes (Kalil, Infectious Diseases Society of America and the American Thoracic Society​ [IDSA/ATS], 2016)
      • New onset of fever
      • Purulent sputum
      • Leukocytosis
      • Decline in oxygenation
  • HAP
    • Defined as pneumonia occurring more than 48 hours after admission, not due to progression of disease process present at admission (Kalil, IDSA/ATS, 2016)
    • Clinical diagnosis
      • Current algorithms have not been found to be more effective than physician evaluation (Kalil, IDSA/ATS, 2016)
    • Tests or scores not included in validated algorithm for determination of HAP include
      • Modified Clinical Pulmonary Infection Score (CPIS) – clinical criteria alone recommended (Kalil, IDSA/ATS, 2016)
      • Procalcitonin (PCT)
      • C-reactive protein (CRP)
  • VAP
    • Defined as pneumonia occurring more than 48 hours after endotracheal intubation (Kalil, IDSA/ATS, 2016)

Laboratory Testing

  • CBC with differential – leukocytosis and differential left shift; however, results may be normal or even demonstrate leukopenia
  • Gram stain and culture – noninvasive collection with semiquantitative culture recommended (Kalil, IDSA/ATS, 2016)
    • HAP
      • May need to induce sputum – nasotracheal suction or endotracheal aspiration may be required if patient unable to produce sputum or recently placed on mechanical ventilation
    • VAP
      • Noninvasive methods include endotracheal aspiration
      • Invasive method with quantitative culture
        • Discouraged due to increased risk (Kalil, IDSA/ATS, 2016)
        • Includes bronchoalveolar lavage (BAL), protected specimen brush (PSB), and blind bronchial sampling
  • Arterial blood gas or oximetry – decreased partial pressure of oxygen in arterial blood (PaO2) saturation
  • CRP – not indicated
    • Not recommended for determination of whether antibiotics are indicated (Kalil, IDSA/ATS, 2016)
  • PCT – data do not currently support use in diagnosis
  • sTREM-1 – data do not support use; being evaluated for use in diagnosis (Kalil, IDSA/ATS, 2016)

Imaging Studies

  • Chest x-ray
    • Infiltrates, effusion, atelectasis, cavities
    • May appear unchanged, particularly in patients with preexisting infiltrates
  • Computed tomography (CT) scan
    • More sensitive than x-ray
    • Difficult to perform in mechanically-ventilated patients


  • PCT
    • Use in combination with clinical criteria to guide discontinuation of antibiotics (CDC, 2010; Kalil, IDSA/ATS, 2016)
  • Antibiotic concentration testing
    • Use laboratory testing to target optimal antibiotic concentrations (refer to Clinical Toxicology Testing – Therapeutic Drug Monitoring for testing details)
    • Improves mortality, ICU length of stay, and clinical cure rates when used to guide treatment

Differential Diagnosis


  • Incidence
    • HAP – 5-10/1,000 hospitalizations
    • VAP – 7-16/1,000 ventilator days
  • Age – increased incidence with older age

Risk Factors

Risk Factors for Multidrug-Resistant Pathogens (Kalil, IDSA/ATS, 2016)

Risk factor




MDR Pseudomonas HAP/VAP

Methicillin-resistant Staphylococcus aureus (MRSA) HAP/VAP

Prior intravenous antibiotics (within 90 days)





Septic shock





Acute respiratory distress syndrome (ARDS) preceding onset





≥5 days of hospitalization prior to onset





Dialysis prior to onset






Usually involves aspiration of oropharyngeal and gastric contents

Clinical Presentation

  • HAP
    • Altered consciousness and fever may be only symptoms
    • Other symptoms include purulent sputum, cough, crackles, rhonchi, wheezing
    • New infiltrate on chest x-ray
    • May present with overt signs and symptoms of sepsis – hypotension, tachycardia, or septic shock
    • Complications
      • Sepsis
      • Pleural effusion
      • Pneumothorax
      • Pneumatoceles
      • Pneumomediastinum
  • VAP
    • Altered consciousness and fever may be only symptoms
    • Other symptoms include purulent sputum, crackles, rhonchi, wheezing
    • New infiltrate on chest x-ray
    • May present with overt signs and symptoms of sepsis – hypotension, tachycardia, or septic shock
    • Complications
      • Sepsis
      • Pleural effusion
      • Pneumothorax
      • Pneumatoceles
      • Pneumomediastinum
      • ARDS
      • Multiorgan failure
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Respiratory Culture and Gram Stain 0060122
Method: Stain/Culture/Identification

CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Bronchoscopy Culture and Gram Stain 0060700
Method: Quantitative Culture/Identification

Procalcitonin 0020763
Method: Immunofluorescence

Explify Respiratory Pathogens by Next Generation Sequencing 2013694
Method: Massively Parallel Sequencing


Kalil AC, Metersky ML, Klompas M, Muscedere J, Sweeney DA, Palmer LB, Napolitano LM, O'Grady NP, Bartlett JG, Carratalà J, Solh AA, Ewig S, Fey PD, File TM, Restrepo MI, Roberts JA, Waterer GW, Cruse P, Knight SL, Brozek JL. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016; 63(5): e61-e111. PubMed

Ventilator-associated Pneumonia (VAP). Center for Disease Control and Prevention. Atlanta, GA [Last updated: May 2012; Accessed: Jul 2017]

General References

Abrahamian FM, Deblieux PM, Emerman CL, Kollef MH, Kupersmith E, Leeper KV, Paterson DL, Shorr AF. Health care-associated pneumonia: identification and initial management in the ED. Am J Emerg Med. 2008; 26(6 Suppl): 1-11. PubMed

Attridge RT, Frei CR. Health care-associated pneumonia: an evidence-based review. Am J Med. 2011; 124(8): 689-97. PubMed

Chastre J, Trouillet J, Combes A, Luyt C. Diagnostic techniques and procedures for establishing the microbial etiology of ventilator-associated pneumonia for clinical trials: the pros for quantitative cultures. Clin Infect Dis. 2010; 51 Suppl 1: S88-92. PubMed

Kollef MH, Morrow LE, Baughman RP, Craven DE, McGowan JE, Micek ST, Niederman MS, Ost D, Paterson DL, Segreti J. Health care-associated pneumonia (HCAP): a critical appraisal to improve identification, management, and outcomes--proceedings of the HCAP Summit. Clin Infect Dis. 2008; 46 Suppl 4: S296-334; quiz 335-8. PubMed

Niederman MS. Hospital-acquired pneumonia, health care-associated pneumonia, ventilator-associated pneumonia, and ventilator-associated tracheobronchitis: definitions and challenges in trial design. Clin Infect Dis. 2010; 51 Suppl 1: S12-7. PubMed

Medical Reviewers

Content Reviewed: 
July 2017

Last Update: October 2017