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AFB Culture, Non-Respiratory (New test)

Item Value
Approval req'd? Yes for:
- CSF unless submitted by neurology or neurosurgery services
- Joint fluid
- Abdominal drainage
- Urine unless from urology patient
- < 2 ml fluid submitted

Contact Microbiology at 353-1268
Available Stat? No
Test code P284
Test group Mycobacteria
Performed by Microbiology
In House Availability Daily, day shift
Method Culture
Collection Instructions
Bone marrow Isolator tubes for bone marrow samples are available from the Hematology laboratory
Urine Collect entire first AM void
Gastric lavage Collect in the early morning. Patient should be fasting prior to collection
FNA TSB broth tubes for FNA samples are available from the Microbiology processing laboratory.

Note: the diagnostic yield for joint and body fluid samples is low. If mycobacterial infection is suspected from these sites, tissue is the preferred specimen.
Container type
Bone marrow Isolator tube (available from hematology laboratory)
Fluid Sterile container
CSF CSF tube or sterile collection tube
Tissue Sterile container
FNA TSB broth tube (Available from Microbiology processing area)
Amount to Collect
Marrow 1 mL
CSF and other fluids 15-20 mL (6 mL for peds)
Urine Entire first AM void (Up to 3 samples may be collected on consecutive days)
Tissue 5 cu mm
Sample type Bone marrow, CSF, body fluids, urine, unfixed tissue, FNA
Preferred volume
Bone Marrow 1 mL
CSF and other fluids 15-20 mL (6 mL for peds)
Urine Entire first AM void
Tissue 5 cu mm
Min. Volume
Bone Marrow 0.5 mL
CSF and other fluids 2 mL
Urine 10 mL
Tissue 3 cu mm
UCSF Rejection Criteria Samples submitted on swabs or in formalin
Processing notes Bone marrow: Store at room temperature until processed. Process specimen immediately upon receipt in microbiology

Gastric lavage: If processing will be delayed by more than 5 hours, give specimen to CLS to neutralize.

Tissue: Grind a piece of tissue using NPC 67 Neutralizing buffer and transfer to blue top centrifuge tube.

CSF: If approved, enter volume used for culture in SDES and AFBVOL in SREQ. (The yield of CSF AFB culture increases with greater specimen volume. Recommended volumes are > 6 ml for pediatrics and 15-20 ml for adults.)

Note: If CSF AFB smear is approved, alert AFB processor and do NOT credit AFB smear.
Normal range No AFB isolated
Critical value First positive acid fast smear. Positive culture (if no or negative smear). First M. tuberculosis isolate. Positive CSF culture. Repeat call only for positive sample from different site or > 2 months since initial call.
Synonyms TB culture; AFB culture; tuberculosis; atypical mycobacteria; MAC; mycobacteriaum avium intercellulare complex; MAI
Blood and bone marrow Room temperature 1 day
Other specimens Refrigerated 3 days
Turn around times Up to 7 weeks
Additional information Separate charges will be billed for AFB smear and AFB culture. Additional charges will be billed for decontamination of samples from non-sterile sites
Smears will be performed on appropriate samples. Samples are run w/o smear when a positive result would not be interpretable because of relatively frequent contamination with nonpathogenic mycobacteria which cannot be reliably differentiated on smear (e.g., in urine or gastric fluid), or for blood, bone marrow, CSF or pleural fluid where the yield of routine testing is low.

Tuberculous arthritis, meningitis, and urinary infection are extremely uncommon diagnoses at this hospital, and cultures should only be requested if the cellular response is highly suggestive of tuberculosis, if there is a history of tuberculosis or close contact with a case, if there is a positive tuberculin test, or if granulomas are found in a biopsy specimen.

Bone marrow is the preferred specimen in non-AIDS patients with disseminated disease, in whom the yield from blood is extremely low.
CPT coding 87116
Last Updated 3/3/2016 12:43:59 PM
Entry Number 673
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