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Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation

The aim of this study was to evaluate the performance of Xpert MTB/RIF Ultra (Ultra) compared with its predecessor, Xpert MTB/RIF (Xpert), in the diagnosis of tuberculosis (TB) in a low TB incidence country. Retrospective analysis was performed on 689 clinical samples received between 2015 and 2018,...

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Autores principales: Mansfield, Mary, McLaughlin, Anne Marie, Roycroft, Emma, Montgomery, Lorraine, Keane, Joseph, Fitzgibbon, Margaret M., Rogers, Thomas R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2022
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9241712/
https://www.ncbi.nlm.nih.gov/pubmed/35471095
http://dx.doi.org/10.1128/spectrum.02345-21
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author Mansfield, Mary
McLaughlin, Anne Marie
Roycroft, Emma
Montgomery, Lorraine
Keane, Joseph
Fitzgibbon, Margaret M.
Rogers, Thomas R.
author_facet Mansfield, Mary
McLaughlin, Anne Marie
Roycroft, Emma
Montgomery, Lorraine
Keane, Joseph
Fitzgibbon, Margaret M.
Rogers, Thomas R.
author_sort Mansfield, Mary
collection PubMed
description The aim of this study was to evaluate the performance of Xpert MTB/RIF Ultra (Ultra) compared with its predecessor, Xpert MTB/RIF (Xpert), in the diagnosis of tuberculosis (TB) in a low TB incidence country. Retrospective analysis was performed on 689 clinical samples received between 2015 and 2018, on which Xpert was performed, and on 715 samples, received between 2018 and 2020, on which Ultra was performed. Samples were pulmonary (n = 830) and extrapulmonary (n = 574) in nature, and a total of 264 were culture positive for Mycobacterium tuberculosis complex (MTBC). The diagnostic performance of both assays was analyzed using culture as the reference standard. The sensitivity of Ultra for culture positive (smear positive and smear negative) MTBC samples, was 93.2% (110/118) compared with 82.2% (120/146) for Xpert (P = 0.0078). In smear negative-culture positive samples, Ultra had a sensitivity of 74.2% (23/31) versus 36.11% (13/36) for Xpert (P = 0.0018). Specificity of both assays was comparable at 94.8% (566/597) for Ultra and 95.8% (520/543) for Xpert (P = 0.4475). The sensitivity of Ultra and Xpert assays among exclusively pulmonary samples was 95.3% (82/86) and 90.3% (84/93), respectively (P = 0.1955), and 87.5% (28/32) and 67.9% (36/53), respectively, among extrapulmonary samples (P = 0.0426). Ultra showed improved performance compared with Xpert in a low TB incidence setting, particularly in smear negative and extrapulmonary MTBC disease. The specificity of Ultra was lower than Xpert, however, this was not statistically significant. IMPORTANCE The study demonstrates the improved sensitivity of the Ultra compared with the Xpert, particularly in smear negative TB disease, for both pulmonary and extrapulmonary samples in a low TB incidence setting. Cycle threshold (Ct) value for both assays was found to positively correlate with time to TB culture positivity, suggesting that Ct and semiquantitative results could be used as indicators of sample MTBC bacillary burden, and thus, perhaps, of transmission potential. This may have implications for the designation of patient isolation precautions.
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spelling pubmed-92417122022-06-30 Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation Mansfield, Mary McLaughlin, Anne Marie Roycroft, Emma Montgomery, Lorraine Keane, Joseph Fitzgibbon, Margaret M. Rogers, Thomas R. Microbiol Spectr Research Article The aim of this study was to evaluate the performance of Xpert MTB/RIF Ultra (Ultra) compared with its predecessor, Xpert MTB/RIF (Xpert), in the diagnosis of tuberculosis (TB) in a low TB incidence country. Retrospective analysis was performed on 689 clinical samples received between 2015 and 2018, on which Xpert was performed, and on 715 samples, received between 2018 and 2020, on which Ultra was performed. Samples were pulmonary (n = 830) and extrapulmonary (n = 574) in nature, and a total of 264 were culture positive for Mycobacterium tuberculosis complex (MTBC). The diagnostic performance of both assays was analyzed using culture as the reference standard. The sensitivity of Ultra for culture positive (smear positive and smear negative) MTBC samples, was 93.2% (110/118) compared with 82.2% (120/146) for Xpert (P = 0.0078). In smear negative-culture positive samples, Ultra had a sensitivity of 74.2% (23/31) versus 36.11% (13/36) for Xpert (P = 0.0018). Specificity of both assays was comparable at 94.8% (566/597) for Ultra and 95.8% (520/543) for Xpert (P = 0.4475). The sensitivity of Ultra and Xpert assays among exclusively pulmonary samples was 95.3% (82/86) and 90.3% (84/93), respectively (P = 0.1955), and 87.5% (28/32) and 67.9% (36/53), respectively, among extrapulmonary samples (P = 0.0426). Ultra showed improved performance compared with Xpert in a low TB incidence setting, particularly in smear negative and extrapulmonary MTBC disease. The specificity of Ultra was lower than Xpert, however, this was not statistically significant. IMPORTANCE The study demonstrates the improved sensitivity of the Ultra compared with the Xpert, particularly in smear negative TB disease, for both pulmonary and extrapulmonary samples in a low TB incidence setting. Cycle threshold (Ct) value for both assays was found to positively correlate with time to TB culture positivity, suggesting that Ct and semiquantitative results could be used as indicators of sample MTBC bacillary burden, and thus, perhaps, of transmission potential. This may have implications for the designation of patient isolation precautions. American Society for Microbiology 2022-04-26 /pmc/articles/PMC9241712/ /pubmed/35471095 http://dx.doi.org/10.1128/spectrum.02345-21 Text en Copyright © 2022 Mansfield et al. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Research Article
Mansfield, Mary
McLaughlin, Anne Marie
Roycroft, Emma
Montgomery, Lorraine
Keane, Joseph
Fitzgibbon, Margaret M.
Rogers, Thomas R.
Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title_full Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title_fullStr Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title_full_unstemmed Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title_short Diagnostic Performance of Xpert MTB/RIF Ultra Compared with Predecessor Test, Xpert MTB/RIF, in a Low TB Incidence Setting: a Retrospective Service Evaluation
title_sort diagnostic performance of xpert mtb/rif ultra compared with predecessor test, xpert mtb/rif, in a low tb incidence setting: a retrospective service evaluation
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9241712/
https://www.ncbi.nlm.nih.gov/pubmed/35471095
http://dx.doi.org/10.1128/spectrum.02345-21
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