Health Care-Associated Pneumonia - HCAP

Diagnosis

Indications for Testing

• New infiltrate on chest x-ray in hospitalized patient
• New fever with cough
• New deterioration in mechanically ventilated patient

Laboratory Testing

• CBC with differential – leukocytosis and differential left shift; however, results may be normal or even demonstrate leukopenia
• Gram stain and culture – sputum
  • Conscious patient – may need to induce sputum; sputum is critical because organisms are more often resistant to standard antimicrobial therapy
  • Ventilator dependent – bronchoalveolar lavage (BAL) or protected specimen brush (PSB) 
    • Confirmed if ≥10³ colony-forming units (CFU)/mL for (PSB) or ≥10⁴ CFU/mL for BAL
• Arterial blood gas or oximetry – decreased partial pressure of oxygen in arterial blood (PaO₂) saturation

Imaging Studies

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

Differential Diagnosis

• Sepsis syndrome
• Adult respiratory distress syndrome
• Congestive heart failure

Clinical Background

Health care-associated pneumonia (HCAP), including hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), are associated with morbidity and mortality and create a substantial economic burden.

Definitions

• HCAP – pneumonia that develops in patients
  • After hospitalization for ≥2 days
  • Residing in nursing home or long-term care facility
  • Attending a hospital or hemodialysis clinic
  • Receiving immunosuppressive therapy or wound care within 30 days of infection
• HAP – pneumonia occurring ≥48 hours post-hospital admission
• VAP – pneumonia occurring >48-72 hours postintubation

Epidemiology

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

Organisms

• Early-onset HAP (≤96 hours following admission) – Escherichia coli, Klebsiella spp, Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, Legionella pneumophila
• Late-onset HAP (>96 hours following admission) – Pseudomonas aeruginosa,methicillin-resistant staphylococcus aureus (MRSA)

Risk Factors

• HCAP
  • Hospitalization ≥2 days within the past 90 days
  • Resident in nursing home
  • Home infusion therapy in past 30 days
  • Long-term dialysis in past 30 days
  • Home wound care in past 30 days
  • Family member with multi-drug resistant infection
• VAP (ICU factors)
  • Ventilator use
  • Administration of H2 blockers
  • Nasogastric tube
  • Tracheostomy
  • >60 years of age
  • Use of paralytics
  • Coma
  • Acute respiratory distress syndrome (ARDS)
  • Admitting diagnosis of burn or trauma
  • Intracranial pressure monitoring

Pathophysiology

• Usually involves aspiration of oropharyngeal and gastric contents

Clinical Presentation

• Altered consciousness and fever may be only symptoms
• 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
  • ARDS
  • Multiorgan failure

Treatment

• Antibiotics
  • Necessary to cover more virulent pathogens that tend to be the etiology in these pneumonias

Prevention

• CDC guidelines for preventing health care-associated pneumonia
• Noninvasive positive pressure ventilation to avoid intubation
• Frequent draining of condensate in ventilator circuit to avoid colonization
• Selective gut decontamination to reduce aspiration risk
  • Not popular in the U.S. due to fear of widespread resistance
• Orotracheal intubation instead of nasotracheal to remove risk of sinusitis
• Incentive spirometry postoperatively in nonventilated patients to reduce risk of atelectasis
• Hand-hygiene measures in all hospital staff and visitors

Indications for Laboratory Testing

• 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