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Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study.
PLoS Med. 2011 Jul; 8(7):e1001067.PM

Abstract

BACKGROUND

The World Health Organization has endorsed the Xpert MTB/RIF assay for investigation of patients suspected of having tuberculosis (TB). However, its utility for routine TB screening and detection of rifampicin resistance among HIV-infected patients with advanced immunodeficiency enrolling in antiretroviral therapy (ART) services is unknown.

METHODS AND FINDINGS

Consecutive adult HIV-infected patients with no current TB diagnosis enrolling in an ART clinic in a South African township were recruited regardless of symptoms. They were clinically characterised and invited to provide two sputum samples at a single visit. The accuracy of the Xpert MTB/RIF assay for diagnosing TB and drug resistance was assessed in comparison with other tests, including fluorescence smear microscopy and automated liquid culture (gold standard) and drug susceptibility testing. Of 515 patients enrolled, 468 patients (median CD4 cell count, 171 cells/µl; interquartile range, 102-236) produced at least one sputum sample, yielding complete sets of results from 839 samples. Mycobacterium tuberculosis was cultured from 81 patients (TB prevalence, 17.3%). The overall sensitivity of the Xpert MTB/RIF assay for culture-positive TB was 73.3% (specificity, 99.2%) compared to 28.0% (specificity, 100%) using smear microscopy. All smear-positive, culture-positive disease was detected by Xpert MTB/RIF from a single sample (sensitivity, 100%), whereas the sensitivity for smear-negative, culture-positive TB was 43.4% from one sputum sample and 62.3% from two samples. Xpert correctly identified rifampicin resistance in all four cases of multidrug-resistant TB but incorrectly identified resistance in three other patients whose disease was confirmed to be drug sensitive by gene sequencing (specificity, 94.1%; positive predictive value, 57%).

CONCLUSIONS

In this population of individuals at high risk of TB, intensive screening using the Xpert MTB/RIF assay increased case detection by 45% compared with smear microscopy, strongly supporting replacement of microscopy for this indication. However, despite the ability of the assay to rapidly detect rifampicin-resistant disease, the specificity for drug-resistant TB was sub-optimal.

Authors+Show Affiliations

The Desmond Tutu HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa. stevelawn@yahoo.co.ukNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

21818180

Citation

Lawn, Stephen D., et al. "Screening for HIV-associated Tuberculosis and Rifampicin Resistance Before Antiretroviral Therapy Using the Xpert MTB/RIF Assay: a Prospective Study." PLoS Medicine, vol. 8, no. 7, 2011, pp. e1001067.
Lawn SD, Brooks SV, Kranzer K, et al. Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study. PLoS Med. 2011;8(7):e1001067.
Lawn, S. D., Brooks, S. V., Kranzer, K., Nicol, M. P., Whitelaw, A., Vogt, M., Bekker, L. G., & Wood, R. (2011). Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study. PLoS Medicine, 8(7), e1001067. https://doi.org/10.1371/journal.pmed.1001067
Lawn SD, et al. Screening for HIV-associated Tuberculosis and Rifampicin Resistance Before Antiretroviral Therapy Using the Xpert MTB/RIF Assay: a Prospective Study. PLoS Med. 2011;8(7):e1001067. PubMed PMID: 21818180.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study. AU - Lawn,Stephen D, AU - Brooks,Sophie V, AU - Kranzer,Katharina, AU - Nicol,Mark P, AU - Whitelaw,Andrew, AU - Vogt,Monica, AU - Bekker,Linda-Gail, AU - Wood,Robin, Y1 - 2011/07/26/ PY - 2011/02/15/received PY - 2011/06/13/accepted PY - 2011/8/6/entrez PY - 2011/8/6/pubmed PY - 2011/12/13/medline SP - e1001067 EP - e1001067 JF - PLoS medicine JO - PLoS Med VL - 8 IS - 7 N2 - BACKGROUND: The World Health Organization has endorsed the Xpert MTB/RIF assay for investigation of patients suspected of having tuberculosis (TB). However, its utility for routine TB screening and detection of rifampicin resistance among HIV-infected patients with advanced immunodeficiency enrolling in antiretroviral therapy (ART) services is unknown. METHODS AND FINDINGS: Consecutive adult HIV-infected patients with no current TB diagnosis enrolling in an ART clinic in a South African township were recruited regardless of symptoms. They were clinically characterised and invited to provide two sputum samples at a single visit. The accuracy of the Xpert MTB/RIF assay for diagnosing TB and drug resistance was assessed in comparison with other tests, including fluorescence smear microscopy and automated liquid culture (gold standard) and drug susceptibility testing. Of 515 patients enrolled, 468 patients (median CD4 cell count, 171 cells/µl; interquartile range, 102-236) produced at least one sputum sample, yielding complete sets of results from 839 samples. Mycobacterium tuberculosis was cultured from 81 patients (TB prevalence, 17.3%). The overall sensitivity of the Xpert MTB/RIF assay for culture-positive TB was 73.3% (specificity, 99.2%) compared to 28.0% (specificity, 100%) using smear microscopy. All smear-positive, culture-positive disease was detected by Xpert MTB/RIF from a single sample (sensitivity, 100%), whereas the sensitivity for smear-negative, culture-positive TB was 43.4% from one sputum sample and 62.3% from two samples. Xpert correctly identified rifampicin resistance in all four cases of multidrug-resistant TB but incorrectly identified resistance in three other patients whose disease was confirmed to be drug sensitive by gene sequencing (specificity, 94.1%; positive predictive value, 57%). CONCLUSIONS: In this population of individuals at high risk of TB, intensive screening using the Xpert MTB/RIF assay increased case detection by 45% compared with smear microscopy, strongly supporting replacement of microscopy for this indication. However, despite the ability of the assay to rapidly detect rifampicin-resistant disease, the specificity for drug-resistant TB was sub-optimal. SN - 1549-1676 UR - https://www.unboundmedicine.com/medline/citation/21818180/Screening_for_HIV_associated_tuberculosis_and_rifampicin_resistance_before_antiretroviral_therapy_using_the_Xpert_MTB/RIF_assay:_a_prospective_study_ L2 - https://dx.plos.org/10.1371/journal.pmed.1001067 DB - PRIME DP - Unbound Medicine ER -