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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
MTB PCR
Test CodeMTB PCR
Alias/See Also
Rule out TB
Includes
Mycobacterium tuberculosis (MTB) complex
If MTB is detected: Rifampin resistance
If MTB is detected: Rifampin resistance
Preferred Specimen
Sputum ONLY!
Minimum Volume
3 mls
Other Acceptable Specimens
None
Instructions
Infection Prevention or Infectious Disease approval required. In patients ONLY. One sample must be an early morning sputum.
Specimens should be collected appropriately in a sealed leak-proof container and transported without delay.
Specimens should be collected appropriately in a sealed leak-proof container and transported without delay.
Transport Temperature
Transport and store specimens at 2–8 °C before processing whenever possible.
Specimen Stability
It is recommended to store at 2–8 °C. If necessary, sputum specimens can be stored at a maximum of 35 °C for up to three days and then at 2–8 °C for an additional seven days.
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
<3 mls
Methodology
Real-time polymerase chain reaction (PCR).
Setup Schedule
Daily between 7:00am and 1:00pm
Report Available
AFTER infectious disease approval has been received the report will be available within 4 hours of arrival in the laboratory. Specimens must be received before 1:00pm on weekdays, and before 11:00am on weekends and holidays. If the specimen is received after these times, results may not be available until the next day.
Reference Range
Not Detected
Comments:
Collection of three sputum specimens at 8-24 hour intervals and including at least one first morning specimen is recommended for acid-fast smears and culture in patients with clinical and chest x-ray findings compatible with tuberculosis. If MTB is suspected, then this should be the first test ordered. (after infectious disease approval has been received)
Routine AFB Culture & Smear (send out test) should be ordered and collected either simultaneously or next time sputum is available after the MTB PCR is collected. Mycobacterial cultures are a more sensitive method than molecular testing for the diagnosis of tuberculosis and are still considered the gold standard due to the sensitivity of culture, the need for susceptibility testing, genotyping or to ascertain the presence of viable organisms in patients currently being treated.
Comments:
Collection of three sputum specimens at 8-24 hour intervals and including at least one first morning specimen is recommended for acid-fast smears and culture in patients with clinical and chest x-ray findings compatible with tuberculosis. If MTB is suspected, then this should be the first test ordered. (after infectious disease approval has been received)
Routine AFB Culture & Smear (send out test) should be ordered and collected either simultaneously or next time sputum is available after the MTB PCR is collected. Mycobacterial cultures are a more sensitive method than molecular testing for the diagnosis of tuberculosis and are still considered the gold standard due to the sensitivity of culture, the need for susceptibility testing, genotyping or to ascertain the presence of viable organisms in patients currently being treated.
Performing Laboratory
Test performed at the West Roxbury Microbiology lab. (857) 203-5954
Last Updated: October 22, 2025
