Tuberculosis (TB) is a severe disease that most often affects the lungs (although other forms affecting kidneys and skin etc. can be seen). Not all persons infected with TB develop disease, overt disease may develop months or years after the initial exposure. Samples from patients suspected of having TB and related micro-organisms are handled in special high containment laboratories to protect laboratory workers and the general public from spread of the disease. Non-tuberculosis mycobacteria (NTM) are environmental organisms that are found mainly in soil and water. The number of NTM isolates being cultured from healthy, and immune compromised patients is rising both globally and nationally and is associated with a rising disease burden.
A wide range of samples such as respiratory specimens, bodily fluids, and tissue samples are examined under the microscope for TB bacteria and are also cultured in sealed bottles. TB is relatively slow growing and may take a number of weeks to appear. A more rapid method that detects specific TB DNA can be used for rapid diagnosis. This laboratory is based at the Freeman Hospital.
Phenotypic antibiotic drug susceptibility testing for clinically significant non tuberculosis Mycobacteria is available on request, where there is an intention to treat.
Non-tuberculous mycobacteria (NTM) are separated into two distinct groups:
Rapidly Growing Mycobacteria i.e. Mycobacterium fortuitum group (M. fortuitum, M. peregrinum, M. fortuitum third biovariant complex), M. chelonae, M. abscessus complex, M. mucogenicum) and M. smegmatis group (M. smegmatis, M. goodii, M. wolinskyi).
Slowly growing NTM, i.e. M. avium complex, M. kansasii and M. marinum.
QuantiFERON-TB Gold Plus testing information
- This test can be used to help diagnose both active and latent tuberculosis (LTBI) infection but cannot distinguish between the two (Culture remains the gold standard for patients suspected of having active TB).
- The cell-mediated immune response to the antigens ESAT-6 and CFP-10 is assessed by the detection, and subsequent quantification of IFN-γ.
Collection
- Patients’ blood should be collected in the 4 specific Quantiferon blood tubes – Negative Control (Grey), TB1 (Green), TB2 (Yellow) and Mitogen (Purple). Each of tube must contain 1ml of blood (Lithium Heparin (3 tubes, 1ml in each) or Quantiferon (4 Tubes, 1ml in each). More or less than 1ml renders the test inaccurate; such samples will not be tested and repeat samples will be requested.
- The samples must arrive within 16 hours of venepuncture and must not be refrigerated, otherwise the test should not be performed.
Before 4pm:
Once collected, Quantiferon Gold samples must be submitted to the laboratory by 4pm on the day on which it is drawn. If the collection time is approaching this deadline, the sending department should inform lab staff of the imminent arrival of these samples so we can look out for their arrival. The direct telephone number for the TB laboratory is 0191 213 8787. A call should also be made to the Blood sciences reception area if the sample is being collected or dropped off at the RVI. The direct line is 24718 Option 1.
After 4pm:
If the sample is taken after this cut off it may still be possible to send. Please communicate with the MV laboratory in the first instance. The sample will need to be sent directly to MV at FH using a hot car or blood bike. The sending dept. must arrange this by contacting the Transport Team on ex 31818 to make an urgent Hot Car request. The MV laboratory must be made aware of the arrangement so they can support the receipt of this samples out of core hours. Until the sample is received in the MV department, we have little control over the sample.
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