Varios

From: The Hospitalist, Supplement: Hospital Medicine and Infectious Diseases
by Scott A. Flanders, MD University of Michigan, Ann Arbor, MI
(This chapter has been reprinted with permission from Williams MV, Hayward R: Comprehensive Hospital Medicine, 1st edition. Philadelphia, WB Saunders, in press.)
Background
Nosocomial pneumonia (NP) is the leading cause of mortality among patients who diefrom hospital-acquired infections. Defined as pneumonia occurring 48 hours or more after hospital admission, NP also includes the subset of ventilator-associated pneumonia (VAP), defined as pneumonia developing 48 to 72 hours after initiation of mechanical ventilation. The incidence of NP is between 5 and 15 cases per 1000 hospital admissions. Healthcare-associated pneumonia (HCAP), part of thecontinuum of NP, describes an increasingly common proportion of pneumonia developing outside the hospital (Table I) (1). Typically afflicting people in a nursing home or assisted living setting, these patients are at risk for antibiotic-resistant-organisms and should be approached similarly to cases of nosocomial pneumonia rather than community-acquired pneumonia. Most of the data informing ourdiagnostic and treatment decisions about NP come from studies performed in mechanically ventilated patients and are extrapolated to make recommendations for non-ventilated patients.
TABLE I. RISK FACTORS FOR HEALTHCARE-ASSOCIATED PNEUMONIA
* Receiving home therapy for:
* IV antibiotics
* Wound care
* Nursing care
* Hospitalized > 2 days in past 90 days
* Residencein nursing home or long-term care facility
* Hospital or dialysis clinic in past 30 days for:
* Dialysis
* Any IV therapy
Adapted from the 2005 ATS/IDSA Guideline for the Management of Adults with Hospital-Acquired, Ventilator-Associated, and Healthcare-Associated Pneumonia.
Mortality attributable to NP is debated, but may be as high as 30%. The presence of nosocomialpneumonia increases hospital length of stay an average of 7–10 days, and in the case of VAP, is estimated to cost between $10,000 and $40,000 per case (2).
Assessment
Clinical Presentation
Signs and Symptoms
Nosocomial pneumonia is usually diagnosed based on clinical grounds. Typical symptoms and signs consist of fever, cough with sputum, and shortness of breath in the setting of hypoxia and a newinfiltrate on chest radiograph (CXR). In the elderly, signs may be more subtle and delirium, fever, or leukocytosis in the absence of cough should trigger its consideration. The likelihood of NP increases among patients with risk factors for microaspiration, oropharyngeal colonization, or overgrowth of resistant organisms (Table II) (3).
Differential Diagnosis
Prior to settling on a diagnosis ofNP, alternative causes of fever, hypoxia, and pulmonary infiltrates should be considered. Most commonly, these include pulmonary embolus, pulmonary edema, or atelectasis. Alternative infectious sources, such as urinary tract, skin and soft-tissue infections, and device-related infections (i.e., central venous catheters) are common in hospitalized patients and should be ruled out before diagnosingnosocomial pneumonia.

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Diagnosis
Diagnostic strategies for NP seek to confirm the diagnosis and identify an etiologic pathogen, thus allowing timely, effective, and streamlined antibiotic therapy. Unfortunately, no consensus exists on the best approach to diagnosing nosocomial pneumonia. After obtaining a complete blood count and blood cultures, you can choose between aclinical or microbiologic diagnostic approach to diagnosis. A clinical diagnosis relies on a new or progressive radiographic infiltrate along with signs of infection such as fever, leukocytosis, or purulent sputum. Clinical diagnosis is sensitive, but is likely to lead to antibiotic overuse. The microbiologic approach requires sampling of secretions from the respiratory tract and may reduce...