Culture of Donor Bone Tissue
Test Code
AFB8
Description
This test is a culture for acid fast bacilli (AFB) in donor bone tissue. This test is used for identifying contamination of donor bone matrices with mycobacteria, especially M. tuberculosis.
AFB culture is the inoculation of donor bone specimen onto multiple media types (including solid and liquid media) followed by monitoring for six weeks. Growth of any mycobacteria is identified for M. tuberculosis and other nontuberculous mycobacteria (NTM). These organisms are identified using first-line assays (i.e. no sequencing is performed for a higher-level identification). Note that a smear from the donor sample is not performed.
Collect
- Donor bone tissue may include "bone slurry" or "viable bone matrix". Bone slurries are typically processed minimally by the donor testing facility and may contain blood. Viable bone matrix is typically a processed specimen that is ready for transplant and therefore should be sterile.
- Specimens should collected and ground into a homogenous matrix.
- Submit a minimum of 1 mL of tissue. Each submitted sample will be treated independently
Unacceptable Conditions
- Donor samples without two unique identifiers will be rejected.
- Donor samples that are received thawed will be rejected.
Stability
Samples should be submitted frozen, and will be thawed for testing.
Notes
AFB smear is not performed.
Performed
Typically all days
Methodology
Samples are cultured on two solid media and one liquid media and incubated for 6 weeks. Mycobacteria are identified to the primary level, especially to detect M. tuberculosis (see AFB4 for further details). No smear is performed. Samples are not digested or decontaminated.
Reported
- The final report for the AFB culture is issued at 6 weeks. Solid media are read at 1, 3 and 6 weeks. and liquid media is read continually.
- Positive solid or liquid media are reported at the time growth is detected and negative cultures reported at 1, 3, and 6 weeks.
- Identification is reported within 3 days to 2 weeks, depending on the method(s) used.
Department
Infectious Disease Laboratory, MycobacteriologySynonyms
Donor tissue, viable bone matrix
Related Tests
VBMTB (Molecular detection of M. tuberculosis in donor tissue)
License Comments
Performed RUO for donor tissue
Reference Interval
Negative for acid fast bacilli.
Interpretation
| Test | Interpretations |
|---|---|
| AFB Culture | Negative cultures are reported as negative for growth. Positive cultures are reported as organisms recovered with a colony count where possible (CFU/mL). |
| AFB Identification | Organisms are identified using first line assays in order to differentiate M. tuberculosis from NTM |
CPT Code
N/A, this is not a clinical test.
Also, note that this is a test algorithm. First, culture is performed. If an organism is recovered, a reflex identification test will be ordered. The identification method used will depend on the organism.
| Method | Billing codes | When is this applied? | |
|---|---|---|---|
| AFB Culture | Culture | CXAFB2 | All samples |
| AFB Identification |
PCR/MALDI-TOF mass Spectrometry | MASID (1st organism), MASI2 (2nd organism), MASI3 (3rd organism) |
If appropriate organisms are recovered |
| Line probe assay | NTMID (1st organism), NTMD2 (2nd organism), NTMD3 (3rd organism) |
If appropriate NTM organisms are recovered | |
| Line probe assay | MTB7T | If the appropriate MTBC organism is recovered. |