Mycobacterium – PCR for MTBC/MAC

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Mycobacterium PCR for MTBC/MAC

Fresh specimens

5.0 ml

Tuberculosis Kit order#: 390042

Mycobacterium PCR for MTBC/MAC

Concentrate

0.5 ml

Tuberculosis Kit order#: 390042

Mycobacterium PCR for MTBC/MAC

Formalin Fixed Tissue or Formalin Fixed Paraffin Embedded (FFPE) block and H & E stained slide

N/A

Tuberculosis Kit order#: 390042

Submission and Collection Notes

1

Collect fresh specimens using aseptic technique in sterile containers without fixative.

2

Contact Public Health laboratory prior to submission of FFPE. FFPE specimens should only be submitted when there is a strong suspicion of tuberculosis disease clinically and epidemiologically, and there is evidence observed on histopathological examination of the tissue (e.g. caseating granulomata visualized on histopathology or acid-fast organisms seen on ZN staining). This information should be part of the histopathology report.  Please note that the Real time PCR assay cannot be used as a “rule out” test.

3

The paraffin block and slide will be returned to the submitter after testing has been completed. A core biopsy may be used in its entirety for TB PCR. Please identify TB as priority.

4

Since mycobacterial organisms are distributed unevenly in tissues, for FFPE samples indicate on the slide the suspect areas (e.g. granulomatous inflammation, caseating granulomata, organisms visualized by ZN etc.) in order to improve the potential for molecular detection of M. tuberculosis complex DNA.

Timing of Specimen Collection

Fresh specimens, or the treated concentrate from a fresh specimen (concentrate must be tested within 72 hours of treatment to maintain sample integrity)

Limitations

Tests performed on smear negative samples do not “rule out” when target DNA is not detected.

Please call Customer Service prior to submission of FFPE.

FFPE samples submitted without prior notice to the laboratory and without the information required as indicated above will not be tested, and will be returned to the submitting laboratory.

Preparation Prior to Transport

Label the container with two identifiers and place specimen in a biohazard bag and seal. Store fresh samples or concentrates at 2-8 °C if transport is delayed more than one hour. Specimens should be transferred to the lab ASAP.

Place specimen container(s) in the biohazard bag and seal bag, and insert the completed requisition in the pocket on the outside of the sealed biohazard bag.

Special Instructions

Store fresh samples or concentrates at 2-8 °C if transport is delayed more than one hour. Specimens should be transferred to the lab ASAP.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Real time PCR for the detection of MTBC and MAC is performed daily, Monday to Friday (excluding holidays).

Turnaround time is up to 4 days from receipt by PHO laboratory.

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are positive for Mycobacterium tuberculosis are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Test Methods

Real time PCR for detection of Mycobacterium tuberculosis Complex (MTBC) and Mycobacterium avium Complex (MAC) DNA is performed on all AFB smear positive specimens from new, untreated patients. Repeat testing is done on AFB smear positive specimens from patients who have had no AFB positive cultures for the past three years. For requests for testing on AFB smear negative specimens, when there is a strong clinical suspicion of TB, the physician must phone the Medical Microbiologist or the lab Operational Lead for approval. Requests written on the requisition will not be accepted unless prior approval is obtained.

FFPE samples are also tested for the presence of MTBC and MAC DNA. The possibility of environmental contamination of these samples, particularly by non tuberculous mycobacteria, means that any result should be considered within the overall clinical picture.

contact lab

Contact Laboratory Customer Service

Laboratory Services

customerservicecentre@oahpp.ca

Updated 22 Oct 2019