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Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment.
Microbiol Spectr. 2021 09 03; 9(1):e0013221.MS

Abstract

High-throughput centralized testing for tuberculosis (TB) and drug resistance is important, but comparative data are limited. In this retrospective cross-sectional study, participants were recruited from Johannesburg, South Africa, and Tbilisi, Georgia. The index tests, Abbott RealTime MTB (RT-MTB) and RealTime MTB RIF/INH (RT-MTB RIF/INH), were performed on specimens stored frozen for an extended period of time (beyond manufacturer-validated specifications) and compared to paired Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF (Xpert) results obtained with fresh specimens. The detection reference standard was the Mycobacterium tuberculosis complex culture, and for resistance detection, it was phenotypic drug susceptibility testing. The median age of 474 participants was 39 (interquartile range [IQR], 31 to 51) years. On decontaminated sputum, Xpert Ultra had a sensitivity of 91%, compared to 77% for RT-MTB, with a difference of +14% (95% confidence interval [CI], +9.2 to +21%; 18/127). On raw sputum, Xpert Ultra exhibited a sensitivity of 89% and Xpert one of 88%, compared to 80% for RT-MTB, exhibiting differences of +10% (95% CI, +3.3 to +18%; 9/93) and +8.6% (95% CI, +2.4 to +17%; 8/93), respectively. Specificity was ≥98% for all tests. All three tests showed high sensitivity and specificity for detection of rifampin resistance. Abbott assays may have lower sensitivity than Xpert and Xpert Ultra for TB detection but similar performance for detection of resistance. The differences in TB detection may be attributable to differences in testing of frozen (Abbott) versus fresh (Xpert) samples. Studies in compliance with manufacturer's instructions are required to compare performance. IMPORTANCE In 2019, 10 million people fell ill with tuberculosis (TB), of whom 1.4 million died. There are few comparative studies of diagnostic assays, particularly those aiming to be used in high-throughput laboratories. One such assay is the Abbott RealTime MTB (RT-MTB) and RealTime MTB RIF/INH (RT-MTB RIF/INH), which uses the m2000 platform already in use in many settings for HIV load testing and allows the diagnosis of TB and resistance to two first-line drugs, rifampin and isoniazid. Our study compared the RT-MTB and RT-MTB RIF/INH to the WHO-recommended Xpert MTB/RIF Ultra and Xpert MTB/RIF. The study is the largest comparative study to date and was performed independent of the manufacturer. The study results suggest that the Abbott RealTime MTB may have a lower sensitivity, but the study may have placed the Abbott test at a disadvantage by using frozen samples and comparing the results to those for fresh samples for the Xpert.

Authors+Show Affiliations

National Heart & Lung Institute, Imperial College Londongrid.7445.2, London, United Kingdom.Foundation for Innovative New Diagnosticsgrid.452485.a, Geneva, Switzerland.Foundation for Innovative New Diagnosticsgrid.452485.a, Geneva, Switzerland. Research Unit, National Center for Tuberculosis and Lung Diseases, Tbilisi, Georgia.Foundation for Innovative New Diagnosticsgrid.452485.a, Geneva, Switzerland.Foundation for Innovative New Diagnosticsgrid.452485.a, Geneva, Switzerland. Division of Tropical Medicine, Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany.

Pub Type(s)

Evaluation Study
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34406811

Citation

Howlett, Patrick, et al. "Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB Against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment." Microbiology Spectrum, vol. 9, no. 1, 2021, pp. e0013221.
Howlett P, Nabeta P, Tukvadze N, et al. Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment. Microbiol Spectr. 2021;9(1):e0013221.
Howlett, P., Nabeta, P., Tukvadze, N., Schumacher, S. G., & Denkinger, C. M. (2021). Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment. Microbiology Spectrum, 9(1), e0013221. https://doi.org/10.1128/Spectrum.00132-21
Howlett P, et al. Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB Against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment. Microbiol Spectr. 2021 09 3;9(1):e0013221. PubMed PMID: 34406811.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Retrospective Diagnostic Accuracy Study of Abbott RealTime MTB against Xpert MTB/RIF Ultra and Xpert MTB/RIF for the Diagnosis of Pulmonary Tuberculosis and Susceptibility to Rifampin and Isoniazid Treatment. AU - Howlett,Patrick, AU - Nabeta,Pamela, AU - Tukvadze,Nestan, AU - Schumacher,Samuel G, AU - Denkinger,Claudia M, Y1 - 2021/08/18/ PY - 2021/8/19/pubmed PY - 2021/12/30/medline PY - 2021/8/18/entrez KW - diagnostics KW - pulmonary KW - pulmonary infection KW - tuberculosis SP - e0013221 EP - e0013221 JF - Microbiology spectrum JO - Microbiol Spectr VL - 9 IS - 1 N2 - High-throughput centralized testing for tuberculosis (TB) and drug resistance is important, but comparative data are limited. In this retrospective cross-sectional study, participants were recruited from Johannesburg, South Africa, and Tbilisi, Georgia. The index tests, Abbott RealTime MTB (RT-MTB) and RealTime MTB RIF/INH (RT-MTB RIF/INH), were performed on specimens stored frozen for an extended period of time (beyond manufacturer-validated specifications) and compared to paired Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF (Xpert) results obtained with fresh specimens. The detection reference standard was the Mycobacterium tuberculosis complex culture, and for resistance detection, it was phenotypic drug susceptibility testing. The median age of 474 participants was 39 (interquartile range [IQR], 31 to 51) years. On decontaminated sputum, Xpert Ultra had a sensitivity of 91%, compared to 77% for RT-MTB, with a difference of +14% (95% confidence interval [CI], +9.2 to +21%; 18/127). On raw sputum, Xpert Ultra exhibited a sensitivity of 89% and Xpert one of 88%, compared to 80% for RT-MTB, exhibiting differences of +10% (95% CI, +3.3 to +18%; 9/93) and +8.6% (95% CI, +2.4 to +17%; 8/93), respectively. Specificity was ≥98% for all tests. All three tests showed high sensitivity and specificity for detection of rifampin resistance. Abbott assays may have lower sensitivity than Xpert and Xpert Ultra for TB detection but similar performance for detection of resistance. The differences in TB detection may be attributable to differences in testing of frozen (Abbott) versus fresh (Xpert) samples. Studies in compliance with manufacturer's instructions are required to compare performance. IMPORTANCE In 2019, 10 million people fell ill with tuberculosis (TB), of whom 1.4 million died. There are few comparative studies of diagnostic assays, particularly those aiming to be used in high-throughput laboratories. One such assay is the Abbott RealTime MTB (RT-MTB) and RealTime MTB RIF/INH (RT-MTB RIF/INH), which uses the m2000 platform already in use in many settings for HIV load testing and allows the diagnosis of TB and resistance to two first-line drugs, rifampin and isoniazid. Our study compared the RT-MTB and RT-MTB RIF/INH to the WHO-recommended Xpert MTB/RIF Ultra and Xpert MTB/RIF. The study is the largest comparative study to date and was performed independent of the manufacturer. The study results suggest that the Abbott RealTime MTB may have a lower sensitivity, but the study may have placed the Abbott test at a disadvantage by using frozen samples and comparing the results to those for fresh samples for the Xpert. SN - 2165-0497 UR - https://www.unboundmedicine.com/medline/citation/34406811/Retrospective_Diagnostic_Accuracy_Study_of_Abbott_RealTime_MTB_against_Xpert_MTB/RIF_Ultra_and_Xpert_MTB/RIF_for_the_Diagnosis_of_Pulmonary_Tuberculosis_and_Susceptibility_to_Rifampin_and_Isoniazid_Treatment_ L2 - https://doi.org/10.1128/Spectrum.00132-21 DB - PRIME DP - Unbound Medicine ER -