UW Hospital and Clinics Lab Test Directory
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Culture, Sputum with Gram Stain
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| Test Code(s): |
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SPUCS / HCSPUCS
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| CPT Code(s): |
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87070, 87205; Additional CPT codes may be added for processing, identification, and susceptibility testing.
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| Test Description: |
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Test Component: Gram stain and culture.
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| Methodology: |
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Culture, Microscopy
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| Clinical Significance: |
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Lower respiratory cultures aid in the differential diagnosis of bacterial, tuberculous, and fungal pneumonia. If smears and cultures are negative for pathogens, the physician is alerted to look for other causes of chest disease such as tumors or viral infections.
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| Days Performed: |
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Daily, 24 hours.
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| Turnaround Time: |
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Routine: Preliminary report: 24 hours. Cultures with no growth or endogenous flora will be reported after 48 hours. Reports on specimens from which pathogens are isolated require a minimum of 48 hours for completion.
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Specimen Requirements
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| Specimen: |
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Expectorated, suctioned or induced sputum, tracheal aspirate
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| Collection Container: |
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Preferred: Sterile screw cap container
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| Specimen Transport: |
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Transport specimen to UWHC Microbiology (B4/231) within 2 hours of collection.
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| Unacceptable Criteria: |
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See Additional Information section for rejection criteria. Also, more than one specimen received from the same patient within 24 hours is not acceptable.
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| Stability: |
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Ambient: 2 hours
Refrigerated: 24 hours
Frozen: Not acceptable
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Interpretation
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Expected Results:
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Endogenous respiratory flora
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| Test Limitations: |
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Since expectorated sputum, tracheal aspirations, and most bronchial washings are contaminated with endogenous oropharyngeal flora (which includes most of the common lower respiratory tract pathogens), cultures of such specimens are neither particularly sensitive nor specific for the diagnosis of bacterial pneumonia and results should be interpreted with caution.
Blood cultures are recommended for the diagnosis of pneumonia, especially for hospitalized patients and those with severe community acquired pneumonia (CAP).
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| Additional Information: |
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A Gram stain is always performed to determine the acceptability of the specimen.
The following criteria are used in rejecting a specimen:
TRACHEAL ASPIRATE/SUCTIONED SPUTA: If there are >10 squamous epithelial cells per low power field and they outnumber the WBC, the specimen will not be cultured. If less than 10 squamous epithelial cells and either no organisms or only yeast are seen on Gram stain, the specimen will not be cultured. If WBC outnumber squamous epithelial cells and no predominating pathogen is present on Gram stain, the specimen will not be cultured.
EXPECTORATED/INDUCED SPUTA: If there are >10 squamous epithelial cells per low power field and they outnumber the WBC, the specimen will not be cultured. If WBC outnumber squamous epithelial cells and no predominating pathogen is present on Gram stain, the specimen will not be cultured. Presence or absence of endogenous upper respiratory flora will be reported.
Susceptibility testing is performed based on lab protocols.
Special methods are necessary for detection of mycobacteria, Legionella, filamentous and dimorphic fungi, Nocardia, and Mycoplasma. See individual entries for additional information.
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Culture-Sputum
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