| Test Name: |
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AFB by PCR
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| Test Code(s): |
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AFBPCR / HCAFBPCR
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| CPT Code(s): |
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87556
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| Clinical Significance: |
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This test detects the M. tuberculosis complex.
This test is always performed on first smear positive specimens submitted to WSLH.
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| Testing Site: |
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Testing will be sent to an approved reference laboratory.
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Specimen Requirements
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| Specimen: |
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See collection instructions.
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| Collection Instructions: |
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Submit 3-10 mL of a primary respiratory specimen (sputum, tracheal aspirate, brochial washing, BAL).
For primary, non-respiratory specimens (body fluids, CSF, stool, urine, lung and other tissues):
Stool: 1 g in sterile container
Tissue Biopsy: 1 g in sterile container
Urine: 40 mL, first-morning, clean catch in sterile container (24-hour pooled specimen is unacceptable)
Body Fluids (pleural, pericardial, etc.): 5-10mL in sterile container
Whole Blood: 10 mL in SPS blood collection tube or Heparin tube (do not use EDTA)
Bone Marrow: As much as available in sterile container or SPS tube
CSF: As much as available in sterile container (minimum of 1 mL required)
Skin Lesions: scrapings or exudates; swabs are not recommended.
Specimens with visible blood will be accepted. All specimens should be submitted in sterile, leak-proof containers.
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| Collection Container: |
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Preferred: State Lab Acid Fast Bacillus (AFB) collection kit
Also Acceptable:
Sterile screw cap container
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| Specimen Processing: |
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TB PCR testing must be performed within 7 days of specimen collection.
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| Specimen Transport: |
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Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.
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| Unacceptable Criteria: |
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Specimens from patients who have undergone antimicrobial therapy for TB for more than 7 days in the past 12 months.
Specimens from patients for whom suspicion of TB is low.
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| Stability: |
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Refrigerated: 7 days
Frozen: Not acceptable
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Interpretation
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| Test Limitations: |
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This tests detects M. tuberculosis complex but does not differentiate among its members.
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| Additional Information: |
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AFB smear and culture must also be ordered on any specimen submitted for PCR testing.
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