- Chest radiograph reveals a new pulmonary infiltrate.
- Fiberoptic bronchoscopy is used for detection of associated anatomic lesions, biopsy for histopathologic workup, or quantitative cultures of conventional bacteria.
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- Assessment of etiologic agents in all hospitalized patients should include pretreatment expectorated sputum for Gram stain and culture and blood cultures.
- Most patients can be treated as outpatients, although all should be evaluated for severity of illness, comorbid factors, and oxygenation.
- For patients with CAP, the predominant etiologic agent is S. pneumoniae, in which multidrug resistance is rapidly increasing.
- Pneumonia caused by atypical agents, such as Legionella pneumophila , Chlamydophilia pneumoniae, or Mycoplasma pneumoniae, cannot be reliably determined clinically. If an atypical agent is suspected, urinary Legionella antigen should be sent. PCR assays for detecting other atypical pathogens may be available in some areas.
- Acute and convalescent serologic testing can retrospectively identify several atypical pathogens including C. pneumoniae, C. burnetii (Q fever), and hantavirus.
- Low-risk CAP patients may be effectively treated at home with oral antibiotics.
- Guidelines giving detailed empiric treatment regimens have been published,with an emphasis on targeting the most likely pathogens within specific risk groups.
- Treatment of immunocompetent outpatients with no recent antibiotic exposure and no comorbidities should consist of doxycycline or a macrolide.
- Treatment of patients with recent antibiotic exposure or comorbidities should include respiratory fluoroquinolone (e.g., moxifloxacin) monotherapy or advanced macrolide (azithromycin or clarithromycin) with or without high-dose amoxicillin.
- Hospitalized patients should be treated with ceftriaxone, 1 g IV daily, or cefotaxime, 1 g IV q8h, plus azithromycin or larithromycin, or monotherapy with a respiratory fluoroquinolone.
- For all critically ill patients, the addition of azithromycin or clarithromycin or a respiratory fluoroquinolone to a beta-lactam regimen is necessary to provide coverage for L. pneumophila.
- Antibiotic therapy should be narrowed if a specific microbiological etiology is obtained.
- Intravenously administered penicillin G, which reaches high concentrations in lung tissue, remains an effective treatment for sensitive S. pneumoniae isolates.
- Thoracentesis of pleural effusions should be performed, with analysis of pH, cell count, Gram stain and bacterial culture, protein, and lactate dehydrogenase. Empyemas should be drained.