Evaluation of Xpert MTB/RIF Versus AFB Smear and Culture to Identify Pulmonary Tuberculosis in Patients With Suspected Tuberculosis From Low and Higher Prevalence Settings

Luetkemeyer, Anne F; Firnhaber, Cynthia; Kendall, Michelle A.; Wu, Xingye; Mazurek, Gerald H.; Benator, Debra; Arduino, Roberto C.; Fernandez, Michel; Guy, Elizabeth; Johnson, Paula I.; Metchock, Beverly; Sattler, Fred R.; Telzak, Edward E.; Wang, Yun F.; Weiner, Marc; Swindells, Susan; Sanne, Ian; Havlir, Diane V.; Grinsztejn, Beatriz; Alland, David

doi:10.1093/cid/ciw035

Cited by 75 publications

(83 citation statements)

References 9 publications

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“…Overall Xpert sensitivity was found not to be influenced by TB prevalence, but by smear status as described in a large meta-analysis performed with the Cochrane meta-analysis [29] and in a recent study by Luetkemeyer et al [30]. Our data support these findings, as performance of Xpert was limited by the high proportion of smear-negative samples.…”

Section: Discussionsupporting

confidence: 88%

Diagnosis of smear-negative tuberculosis is greatly improved by Xpert MTB/RIF

et al. 2017

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BackgroundDiagnosis of pulmonary (PTB) and extra-pulmonary tuberculosis (EPTB) in smear-negative patients can be difficult. We assessed retrospectively the performance of Xpert MTB/RIF system (Xpert, Cepheid) in diagnosing smear-negative tuberculosis (TB), which represents the most common form of TB in a low incidence setting.MethodsPerformance of Xpert was compared to acid-fast microscopic examination using Ziehl-Neelsen (ZN) stain in patients with culture-confirmed TB.Results386 Mycobacterium tuberculosis (MTB) culture-positive samples were detected out of 5170 specimens tested with smear microscopy, Xpert and culture: 323 were both culture- and Xpert-positive, and 63 culture-positive only. Of these, 234 (60.6%) were smear-negative. In addition Xpert detected 40 probable TB cases, based on clinical findings, which were culture-negative.Compared to culture, Xpert showed an overall sensitivity of 83.7% and a specificity of 99.1%; sensitivity was higher for respiratory samples (86.5%) than for non-respiratory samples (76.8%). Xpert sensitivity for smear-negative culture-confirmed TB was 73.1% and was not influenced by TB localization. As sensitivity of microscopy alone was poor (39.4%), Xpert improved both diagnosis of pulmonary TB (Δ = 36.5%) and extra-pulmonary TB (Δ = 63.4%).ConclusionsXpert MTB/RIF is a sensitive method for rapid diagnosis of TB compared to the conventional ZN staining. Xpert can serve as a sensitive and time-saving diagnostic method for microbiological diagnosis of smear-negative TB in countries with a low TB prevalence.

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Section: Discussionsupporting

confidence: 88%

Diagnosis of smear-negative tuberculosis is greatly improved by Xpert MTB/RIF

et al. 2017

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“…Second, our algorithm for discontinuing isolation required not one negative test by Xpert as in the prior modeling study, but two negative tests by Xpert and/or smear on two separate days, as well as completion of sputum collection within isolation. These more stringent requirements were intended to provide a margin of safety because rare false-negative Xpert results have been reported 11,15 . For similar reasons, current guidelines require two negative Xpert results 17 .…”

Section: Discussionmentioning

confidence: 99%

“…Following introduction of a semi-automated, cartridge-based molecular-testing assay(GeneXpert MTB/RIF, Cepheid, Sunnyvale, California, USA; henceforth called “Xpert”) 9 that provides testing results in under two hours, we and others have identified the potential to substantially decrease the duration of isolation 10–12 and hospital costs 13,14 required to evaluate inpatients for active TB. Based on high-quality diagnostic accuracy and modeling studies 10,11,13–15 , regulatory authorities 16 and professional societies 17 have endorsed molecular-testing strategies employing one or two sputum Xpert tests, but little is known about their impact in routine practice. Therefore, we introduced an Xpert-based strategy to guide discontinuation of respiratory isolation for patients undergoing evaluation for active pulmonary TB at a public hospital.…”

Section: Introductionmentioning

confidence: 99%

Association of Rapid Molecular Testing With Duration of Respiratory Isolation for Patients With Possible Tuberculosis in a US Hospital

et al. 2018

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Importance New guidelines recommend that molecular testing replace sputum-smear microscopy to guide discontinuation of respiratory isolation in patients undergoing evaluation for active tuberculosis(TB) in health-care settings. Objective To evaluate the implementation and impact of a molecular-testing strategy to guide discontinuation of isolation. Design Prospective cohort study with a pragmatic, before-and-after-implementation design. Setting Zuckerberg San Francisco General Hospital and Trauma Center. Participants 621 consecutive hospitalized patients undergoing sputum examination for evaluation for active pulmonary TB from January 2014—January 2016. Intervention Implementation of a sputum molecular-testing algorithm using GeneXpert MTB/RIF(Xpert) to guide discontinuation of isolation. Main Outcomes and Measures We measured the proportion of patients with molecular testing ordered and completed; the accuracy of the molecular-testing algorithm in reference to mycobacterial culture; the duration of each component of the testing and isolation processes; length of stay; mean days in isolation and in hospital; and mean cost. We extracted data from hospital records and compared measures before and after implementation. Results Among 320 patients evaluated in the post-implementation period, clinicians ordered molecular testing for 234(73%) patients and received results for 295/302(98%) tests ordered. Median age was 54(interquartile range 44–63), and 161(26%) were women. The molecular-testing algorithm accurately diagnosed all seven patients with culture-confirmed TB and excluded TB in all 251 Mtb-culture-negative patients. Compared to the pre-implementation period, there were significant decreases in median times to final rapid-test result(39.1 vs. 22.4 hours, p<0.001), discontinuation of isolation(2.9 vs. 2.5 days, p=0.001), and hospital discharge(6.0 vs 4.9 days, p=0.003), on average saving $13,347 per isolated non-TB patient. Conclusions and Relevance A sputum molecular-testing algorithm to guide discontinuation of respiratory isolation for patients undergoing evaluation for active TB was safe, feasible, widely and sustainably adopted, and provided substantial clinical and economic benefits. Molecular testing may facilitate more efficient, patient-centered evaluation for possible TB in U.S. hospitals.

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“…If the test is negative, it rules out TB quickly and prevents unnecessary isolation. If the test is positive, it can lead to early diagnosis, rapid initiation of treatment and shorter exposure time of active TB to other community members (17,18).…”

Section: Assessing the Potential For Long Distance Diagnostic Technologymentioning

confidence: 99%

The use of technology to improve health care to Saskatchewan’s First Nations communities

Khan

Ndubuka²,

Stewart³

et al. 2017

Canada Communicable Disease Report

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Evaluation of Xpert MTB/RIF Versus AFB Smear and Culture to Identify Pulmonary Tuberculosis in Patients With Suspected Tuberculosis From Low and Higher Prevalence Settings

Abstract: In the United States, Xpert testing performed comparably to 2 higher-tuberculosis-prevalence settings. These data support the use of Xpert in the initial evaluation of tuberculosis suspects and in algorithms assessing need for respiratory isolation.

Cited by 75 publications

References 9 publications

Diagnosis of smear-negative tuberculosis is greatly improved by Xpert MTB/RIF

Diagnosis of smear-negative tuberculosis is greatly improved by Xpert MTB/RIF

Association of Rapid Molecular Testing With Duration of Respiratory Isolation for Patients With Possible Tuberculosis in a US Hospital

The use of technology to improve health care to Saskatchewan’s First Nations communities

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