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TEXTBOOK PRESENTATION
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Patients with hospital-acquired pneumonia present similarly to patients with CAP although they are often sicker due to a combination of greater comorbidities and an increased likelihood of colonization and infection with virulent pathogens. Those with hospital-acquired pneumonia may be recovering from surgery when fever or delirium heralds the development of hospital-acquired pneumonia.
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Hospital-acquired pneumonia is defined as pneumonia that develops ≥ 48 hours after hospital admission.
Ventilator-associated pneumonia is defined as pneumonia that develops ≥ 48 hours after endotracheal intubation.
Pneumonia in such patients is often secondary to multidrug-resistant organisms, including MRSA and gram-negative bacilli including P aeruginosa. They may also be infected with organisms that commonly cause CAP (S pneumoniae and H influenzae).
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EVIDENCE-BASED DIAGNOSIS
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The diagnosis of pneumonia is typically made clinically by the presence of a new lung infiltrate and ≥ 2 of the following: fever > 38°C, leukocytosis or leukopenia, and purulent secretions.
A lower respiratory tract culture is recommended. Samples may include expectorated sputum, endotracheal aspirate, or samples from bronchoscopy (BAL or protected brush specimen). Endotracheal aspirate is preferred in ventilated patients and sputum culture in nonventilated patients.
Blood cultures are recommended for patients with hospital-acquired pneumonia or ventilator-associated pneumonia.
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Antimicrobial coverage is designed to cover S aureus, P aeruginosa, and other gram-negative bacteria.
The 2016 IDSA guidelines recommend coverage of S aureus, P aeruginosa, and gram-negative bacilli for all patients with hospital-acquired pneumonia or ventilator-associated pneumonia. Extended coverage should be given to patients with an increased risk for antibiotic resistance or at an increased risk of death.
An increased risk of resistance should be assumed in areas with a > 10–20% local resistance on antibiogram, in patients receiving antibiotics within the preceding 90 days, and those hospitalized for ≥ 5 days prior to pneumonia.
An increased risk of mortality should be assumed for patients with septic shock, those requiring ventilator support, or new-onset renal replacement therapy.
Extended coverage includes vancomycin or linezolid for possible MRSA infection and 2 antipseudomonal antibiotics.
Aerosolized antibiotics in addition to IV antibiotics may be useful in select patients.
Culture data and susceptibility should guide antimicrobial therapy when it becomes available.