Xpert MTB/RIF Ultra and Xpert MTB/RIF assays for extrapulmonary tuberculosis and rifampicin resistance in adults

Kohli, Mikashmi; Schiller, Ian; Dendukuri, Nandini; Yao, Mandy; Dheda, Keertan; Denkinger, Claudia M.; Schumacher, Samuel G; Steingart, Karen R

doi:10.1002/14651858.cd012768.pub3

Cited by 106 publications

(115 citation statements)

References 324 publications

(34 reference statements)

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“…Due to the low sensitivity and specificity of AFB microscopy when compared with culture method ( Karadaǧ et al, 2013 ; Molicotti et al, 2014 ; Pk et al, 2017 ; Bahr et al, 2018 ), molecular methods (as Xpert ® MTB/RIF assay) were introduced to improve the speed and specificity of TB diagnosis mainly in the context of extrapulmonary and FFPE samples, when bacterial load is low, and culture is not even possible. Sensitivities of Xpert ® MTB/RIF and its ultra version reported in fresh non-FFPE clinical samples, so far, are always higher than 60% ( Tortoli et al, 2012 ; Sauzullo et al, 2016 ; Lee et al, 2017 ; Bahr et al, 2018 ; Dorman et al, 2018 ; Sarfaraz et al, 2018 ; Sulis et al, 2018 ; Aydemir et al, 2019 ; Kohli et al, 2021 ) and can reach more than 90% only in some body districts ( Mazzola et al, 2016 ). The few data available regarding the Xpert assay performances in FFPE samples are based on a few clinical biopsies and reported a wide range of sensitivities, which were not even concordant (from 97.6% in the case of the Ultra version to 53.2% in the case of the first MTB/RIF assay) ( Seo et al, 2014 ; Du et al, 2019 ; Njau et al, 2019 ; Budvytiene and Banaei, 2020 ; Huang et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Rapid Detection and Quantification of Mycobacterium tuberculosis DNA in Paraffinized Samples by Droplet Digital PCR: A Preliminary Study

et al. 2021

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Background: Rapid and reliable diagnosis of tuberculosis (TB) represents a diagnostic challenge in compartmentalized extrapulmonary TB infection because of the small number of mycobacteria (MTB) and the frequent lack of fresh samples to perform culture. Here, we estimate the performances of homemade droplet digital PCR (ddPCR)-based assays against culture in 89 biopsies, for those fresh and formalin-fixed and paraffin-embedded (FFPE) subsamples were available.Methods: MTB diagnosis in fresh subsamples was performed by culture. Fresh subsamples were also analyzed for acid-fast bacilli smear-microscopy (AFB) and Xpert® MTB/RIF (Xpert). MTB examination was repeated in blind in the 89 FFPE subsamples by in-house ddPCR assays targeting the IS6110 and rpoB. Analytical sensitivity of ddPCR assays was evaluated using serial dilution of H37Rv strain. Limit of detection (LOD) was calculated by probit analysis. Results were expressed in copies/106 cells.Results: IS6110 and rpoB ddPCR assays showed a good linear correlation between expected and observed values (R2: 0.9907 and 0.9743, respectively). Probit analyses predicted a LOD of 17 and 40 copies/106 cells of MTB DNA for IS6110 and rpoB, respectively. Of the 89 biopsies, 68 were culture positive and 21 were culture negative. Considering mycobacterial culture as reference method, IS6110 assay yielded positive results in 67/68 culture-positive samples with a median interquartile range (IQR) of 1,680 (550–8,444) copies/106 cells (sensitivity: 98.5%; accuracy: 98.9). These performances were superior to those reported by the rpoB assay in FFPE subsamples (sensitivity: 66.20%; accuracy: 74.1) and even superior to those reported by Xpert and AFB in fresh subsamples (sensitivity: 79.4 and 33.8%, respectively; accuracy: 84.3 and 49.4, respectively). When Xpert and AFB results were stratified according to mycobacterial load detected by rpoB and IS6110 ddPCR, bacterial load was lower in Xpert and AFB negative with respect to Xpert and AFB-positive samples (p = 0.003 and 0.01 for rpoB and p = 0.01 and 0.11 for IS6110), confirming the poor sensitivity of these methods in paucibacillary disease.Conclusion: ddPCR provides highly sensitive, accurate, and rapid MTB diagnosis in FFPE samples, as defined by the high concordance between IS6110 assay and culture results. This approach can be safely introduced in clinical routine to accelerate MTB diagnosis mainly when culture results remain unavailable.

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Section: Discussionmentioning

confidence: 99%

Rapid Detection and Quantification of Mycobacterium tuberculosis DNA in Paraffinized Samples by Droplet Digital PCR: A Preliminary Study

et al. 2021

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“…Moreover, most of the extrapulmonary specimens were oligosaccharides at the initial stage of the disease, making the diagnosis of various tests less sensitive. For example, MTB culture reduces sensitivity to paucibacillary infection and take several weeks to produce results (19). We also found that, unlike RR/MDR-PTB, RR/MDR-EPTB relies more on Xpert to establish the diagnosis.…”

Section: Discussionmentioning

confidence: 72%

Epidemiology of HIV-negative Rifampicin Resistance /Multidrug-Resistant Extrapulmonary Tuberculosis: 5 Years-experience From a National Tuberculosis Clinical Research Center in China

Ma¹,

Fan²,

Liu³

et al. 2021

Preprint

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Background: China is a region with a high global burden of Rifampicin Resistance ／Multidrug-Resistant tuberculosis (RR/MDR-TB) and low HIV incidence. Our aim was to assess the epidemiological and clinical characteristics of RR/MDR-extrapulmonary tuberculosis (EPTB) over the past five years in China to inform national TB control programmes.Methods: We investigated the epidemiological and clinical datas of all MDR/RR-EPTB cases in a TB specialized hospitals in China over a five-year period and compared cases with a cohort of MDR/RR-PTB patients over the same period.Results: Of the 1,700 RR/MDR-TB patients enrolled, 17.76% were EPTB. The incidence of RR／MDR-EPTB were increasing.The most common anatomical site was pleura/chest wall (20.20%). Compared with RR／MDR-Pulmonary tuberculosis (PTB），RR/MDR-EPTB were were predominately female (50.66%, P< 0.01) 、more prone to delay (P<0.01) in RR/ MDR-EPTB detection with the median time of 145（14 ,341）days since first visit、more less likely to develop diabetes (22.85 %, P<0.01) 、more likely to be newly diagnosed ( 56.95%, P<0.01) 、lower successful treatment outcome（69.56%，p <0.01）、more dependent on Xpert (93.71%) for resistance detection、lower culture positive rate (56.95% , P< 0.01). RR/ MDR-EPTB also showed a significantly higher rate of pre-XDR/XDR (32.45%, P <0.01) . Conclusion: RR/MDR-EPTB is different from RR-MDR/PTB in both epidemiology and clinical. Clinicians should recommend Xpert in early stage and use fluoroquinolones cautiously in cases suspected TB.

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“…However, specificity is reduced by 2.7% (95.6% vs. 98.4%). 8 The WHO technical expert group concludes that Ultra has a higher sensitivity than Xpert MTB/RIF particularly in smear-negative culture-positive specimens, extrapulmonary specimens, and testing specimens from HIV-infected patients and children. Among people without HIV infection, for sputum specimens, an initial “trace call” positive result should be confirmed by testing a fresh specimen with clinical and radiological correlation.…”

Section: B Acterial I Nfectionsmentioning

confidence: 99%

Laboratory Diagnosis of Tropical Infections

Basu¹,

Shetty²

2021

Indian Journal of Critical Care Medicine

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A bstract Highlights (1) Blood culture is the gold standard for the diagnosis of bacterial infections. (2) Bone marrow culture is more sensitive than blood culture even in patients with enteric fever receiving antibiotics. (3) Microscopic agglutination test is considered the gold standard for diagnosing leptospirosis; however, now IgM ELISA and polymerase chain reaction (PCR) are more frequently used for diagnosis. (4) Tuberculosis is diagnosed with the help of nucleic acid amplification tests like Xpert MTB/RIF Ultra which also detects rifampicin resistance. Other tests include microscopy, Lowenstein–Jensen and mycobacteria growth indicator tube culture, line probe assay. (5) Tropical rickettsial infections are diagnosed by serological reactions (Weil–Felix, ELISA for antibodies) and PCR. (6) For Brucellosis culture from blood, bone marrow or tissue specimens remain the mainstay in diagnosis. (7) Dengue, Zika, Crimean–Congo hemorrhagic fever, Ebola, hantavirus, rabies are diagnosed with reverse transcriptase-polymerase chain reaction. Serological tests like IgM ELISA or paired sera samples for IgG are also used for diagnosis. How to cite this article Basu S, Shetty A. Laboratory Diagnosis of Tropical Infections. Indian J Crit Care Med 2021;25(Suppl 2):S122–S126.

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Xpert MTB/RIF Ultra and Xpert MTB/RIF assays for extrapulmonary tuberculosis and rifampicin resistance in adults

Cited by 106 publications

References 324 publications

Rapid Detection and Quantification of Mycobacterium tuberculosis DNA in Paraffinized Samples by Droplet Digital PCR: A Preliminary Study

Rapid Detection and Quantification of Mycobacterium tuberculosis DNA in Paraffinized Samples by Droplet Digital PCR: A Preliminary Study

Epidemiology of HIV-negative Rifampicin Resistance /Multidrug-Resistant Extrapulmonary Tuberculosis: 5 Years-experience From a National Tuberculosis Clinical Research Center in China

Laboratory Diagnosis of Tropical Infections

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