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Lab Test Details

Mycobacterium - AFB Smear and Culture

Updated2/25/2025
Search TermsAcid Fast Bacillus (AFB); GeneXpert; Mycobacteria; Mycobacterium tuberculosis (TB); M. tuberculosis; M. avium; NTM
How to OrderOn the General Microbiology Test Request Form (OHA0060), in the "Mycobacteria" section, check the "AFB: Smear/Culture; sputum or primary specimen" box.
AvailabilityCounty and State Public Health entities
PerformedDaily on regular business days
Time to ReportingSmear: within 2 working days after receipt of specimen.
GeneXpert: within 3 working days after receipt of specimen or clinician request, whichever is later.
Culture: up to 9 weeks after receipt of specimen.
CPT Code87015, 87206, 87116, 87552

Specimen Collection Details

CollectionOptimally, collect 5-10 mL of sputum into 50 mL tube provided. Instruct patient to clear saliva from the mouth and rinse mouth with water prior to sputum collection to prevent specimen contamination.

Please review the detailed instructions for collection, packaging, and submission of specimens (pdf) for additional guidance and support.
Optimal Volume5 ml - 10 mL (Not more than 10 mL)
Minimum Volume0.5 mL (volumes under 1.0 mL processed with qualifier)
HandlingStore samples at refrigerated temperatures (2-8ºC) pending transport.
TransportPackage specimens with fully frozen ice packs to maintain refrigerated temperatures during transport.

Transport for receipt at the OSPHL within 24 hours of specimen collection to ensure optimal results. Later delivery times are acceptable but not preferred.
Rejection CriteriaSpecimens are subject to the requirements of the OSPHL Specimen Submission Policy (pdf).
CommentsOriginal material submitted for testing is not retained after receipt and processing at the laboratory.

Specimens received after 5 days of specimen collection may be contaminated with non-AFB organisms and will be processed with a qualifier.

For additional information or assistance, please contact the laboratory at 503-693-4100

Method Details

MethodologyStandard reference methods for AFB smear and Culture
Performance
Specifications		MTBC IS6110:
  • Percent Accuracy - 100%
  • Positive Predictive Value - 100%
  • Negative Predictive Value - 100%
  • Coefficient of Variation - 0.32
  • Misclassification Rate - 0%
  • Limit of Detection - <1 CFU/50uL
MTBC RD9:
  • Percent Accuracy - 100%
  • Positive Predictive Value - 100%
  • Negative Predictive Value - 100%
  • Coefficient of Variation - 0.31
  • Misclassification Rate - 0%
  • Limit of Detection - <1 CFU/50uL
MAC 15S-23S:
  • Percent Accuracy - 100%
  • Positive Predictive Value - 100%
  • Negative Predictive Value - 100%
  • Coefficient of Variation - 0.2
  • Misclassification Rate - 0%
  • Limit of Detection - <2 CFU/uL

Change Log

2/25/2025Detailed instructions for TB specimens attachment document updated
2/19/2025Updated Collection; Transport
4/24/2023Updated Search Terms and How to Order


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