I know PCR will be the best method when it comes to identifying TB, but we have well over 200 samples and PCR won’t be suitable, because it is expensive and we want to cut the cost.
do you have any recommendations on other alternatives to PCR that might be cheaper I’m thinking acid fast stain but the only problem is it takes way too long.
Intradermal tuberculin skin test (TST) is the international choice method for field diagnosis of bovine Tb in live animals and the World Organisation for Animal Health (OIE) recommended difference between the increases in skin thickness for the test to be positive should be at least 4 mm after 72 hours.
For humans
The TB skin test is also called the Mantoux tuberculin skin test (TST). A TB skin test requires two visits with a health care provider. On the first visit the test is placed; on the second visit the health care provider reads the test.
- The TB skin test is performed by injecting a small amount of fluid (called tuberculin) into the skin on the lower part of the arm.
- A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm.
- The result depends on the size of the raised, hard area or swelling.
If you mean identifying M. tuberculosis in biological samples, PCR would nevertheless be the method of choice, given its high specificity. If you have access to a thermocycler, the cost of reagents shouldn’t be that prohibitive if you perform the reactions in a small volume: 10 microliters is quite sufficient.
TST, Quantiferon assays and Gene-Xpert.
Gene-Xpert has taken over primary diagnosis of TB.
Hi Hevar Neaz,
The approach is different depending on the origin of the samples (humans, animals, environment ...), the nature of samples (sputum, serum, milk, feces...), and clinical and epidemiological profile. In animals (cattle), massive tuberculination of animals is often resorted to with the problems of false reactions due to other Mycobacteria (M. avium). Ziehl-Neelsen staining remains faster and less expensive, especially if you have an automatic machine to process numerous samples. But among direct techniques, PCR (more bit expensive) is the most accurate and specific diagnostic tool.
Acid fast zn staining and DST with routine culture in MGIT and LJ's or line probe assays are always gold standard with sputum samples but it's time consuming and Gene-Xpert is almost available in the developing countries in public health facilities due to WHO and Cepheid study.
Gene Xpert is more suitable compared wtih culture,sputum smear and T-spot
Gene Xpert is a good alternative to PCR testing. TB-LAM is also a good choice if the samples to be processed is appropriate for it.
Confocal laser scanning microscopy can be done to identify M. TB
- Badges
- Science method