Pneumonia, Nosocomial (Hospital-Acquired & Ventilator-Associated)

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For further information, see CMDT Part 9-11: Pneumonia

Key Features

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Essentials of Diagnosis

Hospital-acquired pneumonia (HAP) occurs more than 48 hours after admission to the hospital or other health care facility and excludes any infection present at the time of admission
Ventilator-associated pneumonia (VAP) develops more than 48 hours following endotracheal intubation and mechanical ventilation
At least two of the following are present
- Fever
- Leukocytosis
- Purulent sputum
New or progressive parenchymal opacities on chest radiograph

General Considerations

Most common organisms in HAP
- Staphylococcus aureus (both methicillin-sensitive S aureus and methicillin-resistant S aureus)
- Pseudomonas aeruginosa
- Gram-negative rods, including extended spectrum beta-lactamase (ESBL)- producing and non–ESBL-producing organisms (eg, Enterobacter species, Klebsiella pneumoniae, and Escherichia coli)
Organisms seen in VAP
- Acinetobacter species
- Stenotrophomonas maltophilia
Anaerobic organisms may also cause pneumonia in the hospitalized patient
- Bacteroides
- Anaerobic streptococci
- Fusobacterium
Uncommon causes of nosocomial pneumonias
- Mycobacteria
- Fungi
- Chlamydiae
- Viruses
- Rickettsiae
- Protozoal organisms

Clinical Findings

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Symptoms and Signs

Nonspecific
However, two or more clinical findings (fever, leukocytosis, purulent sputum) in the setting of a new or progressive pulmonary opacity on chest radiograph were approximately 70% sensitive and 75% specific for the diagnosis of VAP in one study
Colonization of the pharynx and possibly the stomach with bacteria is the most important step in the pathogenesis of nosocomial pneumonia
See also Pneumonia, Community-Acquired

Differential Diagnosis

Heart failure
Atelectasis
Aspiration
Acute respiratory distress syndrome (ARDS)
Pulmonary thromboembolism
Pulmonary hemorrhage
Drug reactions

Diagnosis

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Laboratory Tests

Blood cultures identify the pathogen in up to 20% of cases
Arterial blood gases help define illness severity and the need for assisted ventilation
Complete blood count and chemistry tests
- Not helpful in identifying the etiologic agent
- However, can assist in determining illness severity and complications
Gram stains and other examinations of respiratory secretions and cultures of respiratory secretions are controversial but may be useful in guiding antibiotic therapy

Imaging Studies

Radiographic findings
- Nonspecific
- Range from patchy opacities to lobar consolidation to diffuse alveolar or interstitial opacities

Diagnostic Procedures

With suspected HAP, secretions obtained by spontaneous expectoration, sputum induction, nasotracheal suctioning and endotracheal aspiration in a patient who subsequently requires mechanical ventilation should be cultured
For patients with suspected VAP, endotracheal aspiration using a sterile suction catheter with semi-quantitative cultures of lower respiratory tract secretions is the recommended method of evaluation

Treatment

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Medications

See Tables 9–11 and 30–5
Treatment is usually empiric and should be started as soon as the diagnosis is suspected
No consensus regimens exist, but guidelines separate patients by disease severity
Duration of antibiotic therapy is 7 days, but should be individualized based on the pathogen, severity of illness, response to therapy, and comorbid conditions

Table 9–11.Recommended initial empiric antibiotics for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).

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Table 9–11. Recommended initial empiric antibiotics for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).

HAP not at high risk for mortality, or VAP with no risk factors for MRSA, MDR, or Pseudomonas and other gram-negative bacilli

USE one of the following:

Piperacillin-tazobactam, 4.5 g intravenously every 6 hours¹

Cefepime, 2 g intravenously every 8 hours¹

Levofloxacin, 750 mg intravenously daily

Imipenem, 500 mg intravenously every 6 hours¹

Meropenem, 1 g intravenously every 8 hours¹

HAP or VAP with risk factors for MRSA but no risk factors for MDR, Pseudomonas, and other gram-negative bacilli

USE one of the following:

Piperacillin-tazobactam, 4.5 g intravenously every 6 hours¹

Cefepime, 2 g intravenously every 8 hours¹

Ceftazidime, 2 g intravenously every 8 hours

Levofloxacin, 750 mg intravenously daily

Ciprofloxacin, 400 mg intravenously every 8 hours

Imipenem, 500 mg intravenously every 6 hours¹

Meropenem, 1 g intravenously every 8 hours¹

Aztreonam, 2 g intravenously every 8 hours

PLUS one of the following:

Vancomycin, 15 mg/kg intravenously every 8–12 hours with goal to target trough level = 15–20 mg/mL (consider a loading dose of 25–30 mg/kg once for severe illness)²

Linezolid, 600 mg intravenously every 12 hours

HAP with risk factors for Pseudomonas and other gram-negative bacilli, but no risk factors for MRSA and not at high risk for mortality

USE one of the following:

Piperacillin-tazobactam, 4.5 g intravenously every 6 hours¹

Cefepime, 2 g intravenously every 8 hours¹

Ceftazidime, 2 g intravenously every 8 hours

Imipenem, 500 mg intravenously every 6 hours¹

Meropenem, 1 g intravenously every 8 hours¹

Aztreonam, 2 g intravenously every 8 hours

PLUS one of the following:

Levofloxacin, 750 mg intravenously daily

Ciprofloxacin, 400 mg intravenously every 8 hours

Gentamicin, 5–7 mg/kg intravenously daily²

Tobramycin, 5–7 mg/kg intravenously daily²

Aztreonam, 2 g intravenously every 8 hours

HAP at high risk for mortality or VAP with risk factors for MRSA and risk factors for MDR, Pseudomonas, and other gram-negative bacilli

USE one of the following:

Piperacillin-tazobactam, 4.5 g intravenously every 6 hours¹

Cefepime, 2 g intravenously every 8 hours¹

Ceftazidime, 2 g intravenously every 8 hours

Imipenem, 500 mg intravenously every 6 hours¹

Meropenem, 1 g intravenously every 8 hours¹

Aztreonam, 2 g intravenously every 8 hours

PLUS one of the following:

Levofloxacin, 750 mg intravenously daily

Ciprofloxacin, 400 mg intravenously every 8 hours

Amikacin, 15–20 mg/kg intravenously daily²

Gentamicin, 5–7 mg/kg intravenously daily²

Tobramycin, 5–7 mg/kg intravenously daily²

Meropenem, 1 g intravenously every 8 hours¹

Polymyxin B, 2.5–3.0 mg/kg per day divided in 2 daily intravenous doses

Colistin: consult clinical pharmacist for assistance with dosing

PLUS one of the following:

Vancomycin, 15 mg/kg intravenously every 8–12 hours with goal to target trough level = 15–20 mg/mL (consider a loading dose of 25–30 mg/kg once for severe illness)²

Linezolid, 600 mg intravenously every 12 hours

CrCl, creatinine clearance; MDR, multidrug resistant; MRSA, methicillin-resistant Staphylococcus aureus.

¹Extended infusions may be appropriate.

²Drug level monitoring and adjustment of dosing are required.

Data from Kalil AC et al. 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 Sept 1;63(5):e61–111.

Outcome

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Prevention

Sucralfate use for gastric ulcer prophylaxis (rather than H₂-receptor antagonists or proton-pump inhibitors) may reduce the incidence of VAP

Prognosis

HAP is the second most common cause of infection among hospital inpatients and is the leading cause of death due to infection with mortality rates ranging from 20% to 50%

When to Refer

Extensive disease
Seriously ill patient, particularly in the setting of comorbid conditions (eg, liver disease)
Progression of disease or failure to improve on antibiotics

References

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Carr C et al. Ventilator-associated pneumonia: how do the different criteria for diagnosis match up? Am Surg. 2019 Sep 1;85(9):992–7.
[PubMed: 31638512]

Kalil AC et al. 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 Sept 1;63(5):e61–111.
[PubMed: 27418577]

Kollef MH et al. Ventilator-associated pneumonia: the role of emerging diagnostic technologies. Semin Respir Crit Care Med. 2017 Jun;38(3):253–63.
[PubMed: 28578550]

Lanks CW et al. Community-acquired pneumonia and hospital-acquired pneumonia. Med Clin North Am. 2019 May;103(3):487–501.
[PubMed: 30955516]

Llitjos JF et al. Prevention of early ventilator-associated pneumonia. N Engl J Med. 2020 Apr 23;382(17):1672–3.
[PubMed: 32320588]

Noguchi S et al. Pneumonia severity assessment tools for predicting mortality in patients with healthcare-associated pneumonia: a systematic review and meta-analysis. Respiration. 2017;93(6):441–50.
[PubMed: 28449003]

Ranzani OT et al. Invasive and non-invasive diagnostic approaches for microbiological diagnosis of hospital-acquired pneumonia. Crit Care. 2019 Feb 18;23(1):51.
[PubMed: 30777114]

Younan D et al; UHRISES Research Consortium. Factors predictive of ventilator-associated pneumonia in critically ill trauma patients. World J Surg. 2020 Apr;44(4):1121–5.
[PubMed: 31773217]

Zaragoza R et al. Update of the treatment of nosocomial pneumonia in the ICU. Crit Care. 2020 Jun 29;24(1):383.
[PubMed: 32600375]

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Key Features

Essentials of Diagnosis

General Considerations

Clinical Findings

Symptoms and Signs

Differential Diagnosis

Diagnosis

Laboratory Tests

Imaging Studies

Diagnostic Procedures

Treatment

Medications

Outcome

Prevention

Prognosis

When to Refer

References

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