Fast Plaque TB test is a bacteriophage assay for the determination
of Mycobacterium tuberculosis (MTB) complex in decontaminated sputum
samples.
Tuberculosis is a bacterial disease spread by infectious airborne
droplets containing Mycobacterium tuberculosis (occasionally Mycobacterium
bovis or Mycobacterium africanum). It is estimated by the WHO that
approximately one third of the world's population is infected with
M. tuberculosis, resulting in 9 million new cases of TB each year
leading to 3 million deaths annually.
Today, in locations where most tuberculosis is found the diagnosis
of tuberculosis is often based upon both laboratory findings and
clinical signs and symptoms. The laboratory test most often used
to diagnose TB is microscopy for the examination of sputum specimens
obtained from symptomatic patients who take the initiative to visit
a health care facility. Sputum smear microscopy will identify the
most infectious cases of TB. However, it is accepted that this approach
would also miss a substantial number of cases, which later would
become sputum smear microscopy positive and infectious. Culture
of digested and decontaminated sputum is a more sensitive test for
the diagnosis of TB. However, a culture of M. tuberculosis takes
several weeks to grow. This will result in a delay in the diagnosis
of TB that may then lead to further spread of disease.
Principle & Procedure
|
The sample is mixed with Mycobacteriophages. If the M. tuberculosis
is in the sample the phage will infect and grow inside the
bacilli. |
|
All unabsorbed phages
are then inactivated using a phagicidal chemical (Virucide);
while the phages which have infected the viable TB bacilli
remain protected and continue to replicate |
|
After replication the progeny bacteriophages are released
and detected by mixing with fast growing non-pathogenic helper
cells (M. smegmatis) |
|
The mycobacteriophages
in turn infect, replicate and lyse these helper cells and
the lysis is detected as plaque (Clear Zone) |
