Diagnostic performance of GenoType® MTBDRplus line probe assay

Diagnostic performance of GenoType® MTBDRplus line probe assay: Beuy Joob, Viroj Wiwanitkit



The International Journal of Mycobacteriology 2017 6(3):322-322



Dear Editor,

The publication on “Diagnostic performance of GenoType ^® MTBDRplus line probe assay” by Idrees et al. is very interesting.^[1] Idrees et al. concluded that “MTBDRplus detected TB more rapidly and accurately than smear microscopy with significant accuracy for isoniazid (INH) and rifampicin (RMP) resistance. Its use in clinical practice would lead to rapid detection and effective management.”^[1] In fact, MTBDRplus can be useful, but there are many considerations. First, the cost of test is an important concern for many laboratories. According to a study from Africa titled, “MTBDRplus line probe assay cost $23.46/sample,”^[2] Shah et al. noted that “reference laboratories must balance costs with performance characteristics and the need for rapid results.”^[2] We would like to share experience from our countries. The “cost associated with widespread implementation” is a big topic that requires assessment.^[3] Due to high cost, some laboratories do not provide the service while others wait to get an appropriate amount of sample for testing. Therefore, the rapid test might not be cost-effective and not economically sounded. Second, the diagnostic property of the test is a big concern. In a recent report from Pakistan, “the major concern with the GenoType ^® MTBDRplus assay was false-negative results.”^[4] Javed et al. reported that “the assay was unable to detect 30 (30/100; 30%) strains resistant to INH and 23 (23/100; 23%) strains resistant to RMP.”^[4] The similar diagnostic problem was also reported from Nigeria ^[5] and China.^[6] In another report from South Africa, the sensitivity of MTBDRplus was also lower than other available assays.^[7]Recently, Nosova EIu et al. performed a study to compare the performance of MTBDRplus with other available tests and found that TB-Biochip, not MTBDRplus, is the only acceptable molecular assay that was sensitive enough for detection and for revealing multidrug-resistant clinical samples.^[8] Therefore, the problem of the accuracy of the diagnosis is still another big problem in using MTBDRplus. Based on these data, without comparison and concern on cost-effectiveness, the conclusion and suggestion to use the MTBDRplus in clinical practice in any setting seems to be too preliminary.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 

References

1.	Idrees F, Irfan M, Jabeen K, Farooqi J, Hasan R. Diagnostic performance of GenoType® MTBDRplus line probe assay in bronchoalveolar lavage for pulmonary tuberculosis diagnosis in sputum scarce and smear-negative patients. Int J Mycobacteriol 2017;6:122-6.   [PUBMED]  [Full text]
2.	Shah M, Chihota V, Coetzee G, Churchyard G, Dorman SE. Comparison of laboratory costs of rapid molecular tests and conventional diagnostics for detection of tuberculosis and drug-resistant tuberculosis in South Africa. BMC Infect Dis 2013;13:352.
3.	Anek-Vorapong R, Sinthuwattanawibool C, Podewils LJ, McCarthy K, Ngamlert K, Promsarin B, et al. Validation of the GenoType MTBDRplus assay for detection of MDR-TB in a public health laboratory in Thailand. BMC Infect Dis 2010;10:123.
4.	Javed H, Jamil N, Jagielski T, Bakula Z, Tahir Z. Evaluation of genotype MTBDRplus assay for rapid detection of isoniazid and rifampicin resistance in Mycobacterium tuberculosis clinical isolates from Pakistan. Int J Mycobacteriol 2016;5 Suppl 1:S147-8.
5.	Felkel M, Exner R, Schleucher R, Lay H, Autenrieth IB, Kempf VA, et al. Evaluation of Mycobacterium tuberculosis drug susceptibility in clinical specimens from Nigeria using genotype MTBDRplus and MTBDRsl assays. Eur J Microbiol Immunol (Bp) 2013;3:252-7.
6.	Tan Y, Li Q, Wang Q, Sun H, Chen J, Cai X, et al. Evaluation of the MTBDRplus 2.0 assay for the detection of multidrug resistance among persons with presumptive pulmonary TB in China. Sci Rep 2017;7:3364.
7.	Nosova EIu, Krasnova MA, Galkina KIu, Makarova MV, Litvinov VI, Moroz AM. Comparing performance of “TB-BIOCHIP”, “Xpert MTB/RIF” and “genotype MTBDRplus” assays for fast identification of mutations in the Mycobacterium tuberculosis complex in sputum from TB patients. Mol Biol (Mosk) 2013;47:267-74.
8.	EIu N, Krasnova MA, Galkina KIu, Makarova MV, Litvinov VI, Moroz AM. Comparing performance of “TB-BIOCHIP”, “Xpert MTB/RIF” and “genotype MTBDRplus” assays for fast identification of mutations in the Mycobacterium tuberculosis complex in sputum from TB patients. Mol Biol (Mosk) 2013;47:267-74.

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