How to test the presence of MAP? Why blood culture?
What about serology? PCR (molecular testing)?
We offer three separate tests to identify MAP in the blood, blood culture (to grow MAP from
peripheral blood), serology (to determine if there are antibodies in the circulation against MAP) or by
molecular amplification of DNA from the mycobacteria by PCR/sequencing. Each method has
advantages and disadvantages in clinical setting to answer the same question from different aspects,
and they are elaborated as the following.
Blood culture of MAP is the gold standard for determination of active MAP infection, and it is ideal to have a blood culture result before treatment. Culture of MAP is a tedious and expensive process, and it takes 4-12 weeks to get results, since MAP is a slow grower with special requirements to grow. There is no commercial laboratory available to perform this test to date, and that’s why we are here to help.
Once the patient is infected by MAP, the patient’s body will react to the mycobacteria by generating specific antibody against MAP, and the determination of the antibody against MAP will provide an important information. However, the antibody determination is not sensitive (varies from 40-70% based on animal studies). In another word, if the antibody test is negative, the patient could still be infected.
Molecular testing by PCR/sequencing
PCR testing is a fast and accurate method to determine the presence of MAP DNA in blood. In conjunction with DNA sequencing, it will provide accurate assessment of MAP DNA in the body. However, just like any other PCR test, it is testing the presence of DNA, not living mycobacterial organisms. It does not say if the mycobacteria are alive, or dead. It is a wonderful complimentary test to culture and serology.