The TST is easily administered and if it works correctly, results can be obtained within 72 hours.

1800 WordsApr 23, 20198 Pages
The TST is easily administered and if it works correctly, results can be obtained within 72 hours. Although the test has its advantages, there are disadvantages to the test also. Some people may react to the TST even if they are not infected with M. tuberculosis. Possible causes of a false-positive reaction include previous BCG vaccination or infection with mycobacteria other than M. tuberculosis. Some people may not react with the TST even though they are infected with M. tuberculosis. The false-negative reaction may be the result of a recent TB infection (within 8-10 weeks of exposure) or a recent live-virus vaccine (eg. Measles) (Centre for Disease Control and Prevention, 2011).The IGRA has various advantages. Only a single visit from…show more content…
The sensitivity of the Xpert MTB/RIF was considerably better than the sensitivity of the Cobas TaqMan MTB assay. The difference in PCR technology could account for the substantial difference in sensitivity. The Xpert MTB/RIF uses heminested real-time PCR technology whereas the Cobas Taqman MTB assay uses simple real-time PCR technology. The Xpert MTB/RIF assay system also looks to be less susceptible to cross-contamination than other PCR based methods. Cross-contamination could give false positive results (Blakemore, et al., 2010). A major benefit of these molecular methods is that they both provided results in less than 2 hours and required very little handling. The Xpert MTB/RIF assay system in particular requires very little handling by laboratory staff as extraction, amplification and detection occur in a single-use cartridge, which ensure minimal contamination of the specimen. There is a greater chance for contamination in the Cobas TaqMan MBT assay as the specimens are extracted manually. Another benefit of the Xpert MTB/RIF kit is that samples can be processed individually as they are needed, whereas the Cobas TaqMan MTB assay requires at least 10 samples and 2 controls to be processed at a time in order not to waste reagents. These molecular methods represent great progress made in methods for detecting M. tuberculosis. Reference culture methods can talk up to 6 weeks to get a final diagnosis whereas the real-time PCR and

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