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SYMPTOMS/EXAM

■ Fever, dyspnea, or cough productive of purulent or bloody sputum are

most common.

■ Pleuritic chest pain, tachypnea, and abnormal breath sounds

■ In the elderly, the presenting complaint may be vague and nonspecific, eg,

altered mental status, poor appetite, or a fall.

DIFFERENTIAL

■ Hospital-acquired pneumonia:Occurs after at least 5 days of inpatient care

and frequently caused by Pseudomonas,Enterobacter,Legionella, or S. aureus.

■ Also consider pulmonary embolism, bronchiectasis, bronchitis, CHF.

DIAGNOSIS

■ Suspect based on clinical presentation

■ It is not possible to differentiate atypical from typical infections based on

clinical criteria.

■ CXR

■ Radiographic findings cannot accurately predict the microbial cause,

but lobar infiltrates are more likely due to typical bacterial pathogens

and interstitial infiltrates due to atypical pathogens.

■ The initial CXR may be negative in patients with significant dehydration.

■ Microbiological diagnosis is reserved for more seriously ill admitted patients:

■ Blood cultures: Low yield overall but accurately identifies organism

when positive

■ Sputum Gram stain and culture. Diagnostic sample must have < 10

epithelial cells and >25 WBC/hpf. See Table 10.9 for Gram stains of

common organisms that cause pneumonia.

■ Specific culture and antigen testing if Legionellasuspected

■ Pleural fluid evaluation, if present.

■ Findings associated with poor outcome:

■ Pleural effusion

■ Multilobar involvement

■ Pleural effusion

THORACIC AND RESPIRATORY

DISORDERS

TABLE 10.9. Gram Stains of Common Organisms That Cause Pneumonia

ORGANISM GRAMSTAI NFINDINGS

S. pneumoniae Gram+lancet-shaped cocci, usually in pairs, PMNs

H. influenzae Gram– coccobacillus, PMNs

S. aureus Gram+cocci in clusters, PMNs

Klebsiellasp. Gram– rod, PMNs

Legionella sp. Weakly Gram– rod, PMNs

Oral flora (aspiration) Mixed Gram+and – cocci and rods, PMNs

Atypicals Few bacteria, many PMNs or monos

Viral

Legionella