Florida Bureau of Public Health laboratories
Acid-Fast Bacilli Culture
The AFB culture test provides results for the detection of acid-fast bacilli by solid culture on LJ and liquid culture by BACTEC MGIT 960.
Analyte(s)
Acid-fast bacilli bacteria
Test Code
3100
Testing Location
Testing Department
Mycobacteriology (TB)
Pre-approval Required?
No
Required Forms
BPHL Test Requisition, DH1847
(not needed if orders are placed via electronic order)
Minimum Volume
At least 5 mL of unprocessed specimen or
At least 0.5 – 1 mL of processed specimen
Turn Around time
6 weeks after receipt at the laboratory.
Supply Ordering
Supplies may be requested from your servicing laboratory. Supplies ordered from the BPHL should only be used for specimen sent to the BPHL for testing.
Collection Media
50 mL sterile conical tube
Specimen Sources
Sputum or bronchoalveolar lavage, stool, urine, CSF, tissue, and any source not listed under unsatisfactory specimen.
Specimen Labeling
Specimen must be labeled with at least two unique patient identifiers, e.g., name and DOB.
Information on the specimen must match the requisition and/or test order.
Special SPecimen Preparation
Gastric Lavage specimens must be neutralized with 100 mg of sodium carbonate if the time between collection and processing exceeds 4 hours.
Storage Conditions
Blood must be stored and shipped at room temperature (15-28° C) until time of shipment.
Store all other specimens refrigerated at 2 – 8° C until time of shipment.
Packaging and Shipping
Specimens can be shipped within the 2-28° C temperature range, except for urine specimens.
Urine specimen must be shipped refrigerated (2 – 8° C). Processed urine sediments may be shipped within the 2-28° C temperature range and must be clearly marked on the requisition as “Processed”.
Separate specimens to prevent cross-contamination and shipped in double container.
unsatisfactory specimen
1) Formalin fixed or paraffin-embedded tissues
2) No patient identification on specimen tube
3) No specimen observed in specimen container
4) Specimen damaged or leaked entirely in transit
5) Gastric aspirates that have not been neutralized
6) Urine specimens arriving outside of acceptable temperature range
7) Blood specimens collected into EDTA tubes or containing coagulated blood are unacceptable
8) Samples cross contaminated due to sample leaking in transit
Interferences and Limitations
Heavy bacterial contamination of primary specimen may lead to contamination of both liquid and solid media cultures.
Reference Range
Negative (No AFB cultured)
Result Indicator
Positive: All positive cultures will be stained for AFB and identified by PRA, or hsp65 DNA Sequencing
Negative: No AFB cultured
Contaminated: Both solid and liquid cultures contaminated
Reference lab
CDC
Reflex testing
Identification of any acid-fast bacilli that grow in either the liquid or solid media.
Cultures positive for Mycobacterium tuberculosis complex (MTBC) will be
reflexed to GeneXpert, Deeplex, and drug susceptibility testing if from new
patient or 60 days since previous DST results.
All specimens other than blood
will have AFB smear performed.