Sunday, March 3, 2013

Tuberculosis Diagnosis!

Hi, Today I'm going to share something about TB! TB - Tuberculosis is generally caused by Mycobacterium tuberculosis. The most common symptom of TB is "non -stop" cough!

They say, many people in India are "carrier" of the bacteria, but not the disease! Oh God! if you are in India, better go and check for this bacteria! The possibility of the spread of the disease could be due to unhygienic conditions!

You spit in public places? you sneeze? cough? No problem, you can sneeze or cough, but be careful! Careful coughing? careful sneezing? yes, you might spread the population this mycobacterium you are carrying (you need not have TB), so, be careful in sneezing and coughing!

Okay, let us come to the point, I started typing this with a view of giving an overview about "the diagnosis of Tuberculosis".

The most common test used for checking TB is "Tuberculin Skin Test". Let me explain you how this is done!

Tuberculin Skin Test!
Let us first look into the principle behind this test. When a person is infected with Mycobacterium tuberculosis, then, he will be carrying antibodies against it. When he/she is injected with the antigen from this bacteria, he will produce an induration (hard bulge in the place where the antigen is injected).  This could be found after sufficient time like 72 hours.This is used for diagnosing TB! In this case, false positive results are obtained when a person tested for the second time using this method.

Antigen? What is the antigen used here? Is that your question? It is the protein which triggers the immune response extracted from the mycobacterium sp.

 Do you think this is enough for diagnosing TB? "Okay, what else one could do for diagnosing TB?" When my professor asked this question in class, I replied "ELISA".

ELISA - Enzyme Linked Immuno Sorbent Assay: Here the blood sample from the patient must be collected and checked for antigen antibody interaction in the well plate. Here we must have the antibody available in our lab. If there is antigen antibody interaction the ELISA produces colour else it won't!

"Okay fine. What else you could do for diagnosing TB?", when my professor questioned further, I replied, "PCR"! He was happy atlast that I had answered as he expected!

PCR: How PCR could be done for diagnosing TB? Mycobacterium genome sequence is available online in the databases and one could design primers based on that and when PCR works, then the person is having TB, else not! Real Time PCR is generally preferred than the normal PCR for avoiding errors.

The advantage of PCR is that one could also say the severity of the disease and dosage of the antibiotic could be given accordingly.

After all, the dosage must be very correct and the antibiotic treatment should not be dropped in the middle to avoid development "multi drug resistant" species!

I had shared whatever I understood as an overview, any doubts? mistakes? suggestions? Feel free to comment!

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