AFB Culture w/ Smear
Order in NUlirt or complete NPHL Test Order Form with Supplemental Forms –
Mycobacterium tuberculosis (MTB) Supplemental


AFB Culture, TB Culture w/ smear, AFBCU


Standard reference procedures for stain and culture. Molecular sequencing used for most identification. DNA probes available for M. tuberculosis complex, M. avium-intracellulare complex, M. gordonae as indicated.


Monday - Friday by 0800. Stat requests are performed by approval of a pathologist.


Sputum:  early morning collection in a sterile leak-proof container. Limit the number of samples to 3 specimens collected consecutively in 8- to 24-hour intervals, with at least one being an early morning specimen.  Early morning sputum specimen is preferred. Approval is required for additional specimens. The number of specimens that should be submitted is related to the results of early smear examinations
Gastric lavages, tissues, body fluids and urine.

  Collection Device:

Early morning sputum and urine in a sterile leak-proof container. Gastric aspirate, body fluid and tissue in a sterile leak-proof container. Store and transport refrigerated at 2-8°C.
Specimen Labeling: Test subject to CLIA regulations and required 2 patient identifiers on specimen container and requisition forms


5-20ml sputum, at least 1-2ml CSF, 5-20ml gastric aspirate, ≥40ml urine, 5-50ml body fluid, or 1 gram of tissue.


Prior to and during shipment:  Refrigerate 2-8°C.

Shipping instructions, including specimen-handling requirements during transport: Seal screw-top tubes with Parafilm™ or tape and place in biohazard bag with absorbent material.
Place specimen inside leak proof secondary container (biohazard bag and if transporting by air, use Tyvek™ Envelope) ) with adsorbent material. The secondary container must be packed inside an approved Category B shipping container filled with dry ice to keep specimen frozen. Position NUlirt packing list or NPHL Test Order form between secondary container and box lid. Seal with tape.  Label outer box as UN3373 Category B, Biological Substance. Transport by NPHL ground courier. If courier not available, ship by FedEx, UPS, or USPS (1st Class, Priority or Express Mail). Follow appropriate DOT/IATA Regulation Guidelines.  For assistance, call NPHL State Training Coordinator at (402) 559-3590.  

 See instructions and shipping address: http://nphl.org/

NUlirt packing list or appropriate paperwork (completed in entirety) must accompany specimens.


Multiple same-site specimens (more than one in 24 hours; exception sputum (see collection instructions), dry material, non-sterile or leaking container, improper volume of sputum (<2ml) or fluids (<1ml), material collected and transported on a swab and stool

  Specimen Stability:

Stable at refrigerated 2-8°C

  Reference Interval:

Preliminary: Acid fast stain at 24 hours, Negative at 4 weeks.
Final: Negative at 8 weeks
Positive cultures are reported as soon as detected. 
Note: Identification performed on positives.
Susceptibilities are performed on M. tuberculosis complex isolates and clinically significant Mycobacterium spp other than M. tuberculosis complex. Other NON- clinically significant mycobacteria are by request only and will be evaluated by Microbiology director.
Susceptibility testing of M. gordonae from sputum is usually inappropriate.
Standard reference procedures for stain and culture. Sequencing procedures are used for rapid growers and other mycobacterium not identified by Hologic AccuProbe DNA probe. DNA probes available for M. tuberculosis complex, M. avium-intracellulare complex, M. gordonae as indicated.

  Reportable Disease:

Report positive MTB complex results immediately to caregiver, local or state health department. Refer to Nebraska DHHS Title 173, Communicable Diseases.  All positive MTB isolated should be submitted to the NPHL for molecular sequencing to supplement and epidemiological investigation. 


Collection of early morning specimens of urine and sputum on each of 3 consecutive days is optimum. Gastric lavage specimens must be neutralized with sodium bicarbonate if transport delayed > 4 hours.
Collect gastric aspirate 8 hours after food ingestion. Suggest collection of gastric aspirates for 3 consecutive days. Indicate source of specimen on the lab form. 
Tissue: submit skin lesions or other tissue; keep moistened with sterile saline. 
Indicate if Mycobacterium other than tuberculosis (MOTT) are suspected. This may expedite identification. Client is notified of positive stain/culture. 
Additional information to include when submitting a specimen for culture; patient's PPD status; BCG immunization history; prior anti-tuberculous therapy.
Contact TB lab at 402-552-3087 for questions.
NUlirt packing list or appropriate paperwork (completed in entirety) must accompany specimens

  Revised: 6/12/2021