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Mycobacterial Culture

Item Value
Approval req'd? Yes, consult with Microbiology lab x3-1268 regarding sample requirements
Available Stat? No
Test code P285
Test group Mycobacteria
Performed by Microbiology
In House Availability Daily, day shift
Collection Instructions Use only Dark green top heparin tubes for blood samples. This is only offered in HIV positive patients.

Isolator tubes for bone marrow samples are available from the hematology laboratory.

Collect 3 separate sputum samples in 8-12 hour intervals, including at least one early morning sample. Sputum samples collected < 8 hours apart are pooled & tested as a single specimen.

Urine should be collected as entire first AM void.

Collect gastric lavage in the early morning. Patient should be fasting prior to collection.

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
Blood Dark green top x2 (DO NOT use Lithium heparin i.e. Light Green top tubes)
Bone marrow Isolator tube (available from hematology laboratory)
Fluid clean container
CSF CSF tube or sterile collection tube
Sputum clean container
Tissue clean container
Amount to Collect
Blood 5 mL
Marrow 1 mL
CSF and other fluids 15-20 mL (6 mL for peds)
Sputum 5 mL
Urine entire first AM void
Tissue 1 gram
Sample type Heparinized whole blood (MAC only), bone marrow, sputum, CSF, gastric fluid, body fluids, urine, unfixed tissue.
Preferred volume
Blood 5 mL
Marrow 1 mL
CSF and other fluids 15-20 mL (6 mL for peds)
Sputum 5 mL
Urine entire first AM void
Tissue 1 gram
Min. Volume
Blood 3 mL
Marrow 0.5 mL
CSF and other fluids 2 mL
Sputum 1 mL
Urine 10 mL
Tissue visible sample
UCSF Rejection Criteria Blood submitted in Lithium heparin (light green top) tube. Samples submitted on swabs. Sputum samples collected < 8 hours apart.
Normal range No AFB isolated
Critical value First positive acid fast smear. Positive culture (if no or negative smear). First M. tuberculosis isolate, positive M. tuberculosis PCR from a respiratory specimen. 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 Positive usually 1-4 weeks, negative 6 weeks
Additional information 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 flood where the yield of routine testing is low.

Blood cultures are performed only for patients with a diagnosis of AIDS and are suitable only for detecting MAC.

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.

Additional charges will be billed for decontamination of samples from non-sterile sites.
CPT coding 87116
Last Updated 10/15/2014 1:49:15 PM
Entry Number 673
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