Culture, Bacterial, Sputum
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Routine culture of sputum.
To identify pathogenic bacterial organisms in the sputum as an indicator for appropriate therapeutic interventions for respiratory infections.
(Method: Aerobic culture on selective and enriched media; microscopic examination of sputum by Gram stain.) The presence of normal upper respiratory tract flora should be expected. Tracheal aspirates and bronchoscopy samples can be contaminated with normal flora, but transtracheal aspiration specimens should show no growth. Normal respiratory flora include Neisseria catarrhalis, Candida albicans, diphtheroids, α-hemolytic streptococci, and some staphylococci. The presence of normal flora does not rule out infection. A normal Gram stain of sputum contains polymorphonuclear leukocytes, alveolar macrophages, and a few squamous epithelial cells.