Xpert MTB/RIF Ultranewer technology

past to future DIAGNOSIS OF TUBERCULOSIS

Dr.T.V.Rao MD

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TB Kills many in the World,Now emerging resistance is a

concern •TB killed 1.8 million people in 2015 and caused TB

disease in 10.4 million.2 An estimated 580,000 TB patients were also resistant to rifampicin, a critical first-line TB drug. However, less than 70% of new TB cases and only 25% of drug-resistant cases were diagnosed or treated in 2015, leaving significant gaps in our understanding of the disease and its global effect on the population

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Limitations with Direct Microscopy with Ziehl–Neelsen staining;• Direct microscopic examination is

a fast and inexpensive method to identify acid-fast bacilli through the use of Ziehl–Neelsen staining; however, it is limited by poor sensitivity and the inability to discriminate between mycobacterial species, which can be a relevant issue especially among children and immunocompromised individuals.

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Detection of AFB with Fluorescence microscopy

• Fluorescence or light-emitting diode microscopy may be an alternative to traditional microscopy with a moderate improvement in sensitivity (+10%) but also slightly higher costs and the need for well-trained technicians

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Culture remains the gold standard with Many Limitations

• Culture remains the gold standard technique for the diagnosis of TB, even though its large-scale use is limited by the long waiting time due to the slow growth rate of mycobacteria (~2–6 weeks in liquid media) with consequent diagnostic delays; furthermore, the need for biosafety level 3 laboratory infrastructures and highly skilled laboratory technicians who are often lacking especially in resource-constrained settings is another significant limitation.

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Tuberculin skin dependent on Immunological status of Infected patient

• Tuberculin skin test and interferon-gamma release assay are currently recommended for the diagnosis of LTBI, but have a marginal role in the detection of TB cases, as they cannot distinguish between active and latent infection and may be influenced by the patient’s immune statue

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Drug Resistance is concern in Tuberculosis

• The emergence and spread of multidrug-resistant strains is currently among the greatest concerns, which may hinder the achievement of future goals to ensure early case detection and prompt referral to specialised centres for treatment initiation and follow-up

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WHO RECOMMENDS A NEW MOLECULAR BASED METHOD

• WHO currently recommends a biomolecular test as the initial diagnostic tool in case of TB suspect. Among the several commercially available nucleic acid amplification tests, Xpert MTB/Rif (Cepheid, Sunnyvale, CA, USA) is the most efficient and suitable for implementation in resource-constrained settings (at the point-of-care level), as it does not require any sophisticated laboratory facility, is fully automated and provides the results in <2 h

WHAT IS Xpert MTB/RIF

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Xpert MTB/RIF• The Xpert MTB/RIF is a cartridge based nucleic acid

amplification test, automated diagnostic test that can identify Mycobacterium tuberculosis (MTB) DNA and resistance to rifampicin (RIF) by nucleic acid amplification test (NAAT). It was co-developed by the laboratory of Professor David Alland at the University of Medicine and Dentistry of New Jersey (UMDNJ).] Cepheid Inc. and Foundation for Innovative New Diagnostics, with additional financial support from the US National Institutes of Health (NIH).

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Xpert MTB/RIF Detects the Rifampicin resistance and presence of Tuberculosis

• The existing test, Xpert MTB/RIF, was introduced in 2010 and transformed the landscape of TB diagnosis by offering rapid, sensitive diagnosis of TB and rifampicin resistance.

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About GeneXpert Systems and Xpert

Tests• With more than 10,000 systems in

182 countries, the GeneXpert System is the world’s most popular molecular diagnostics’ instrument. The GeneXpert System’s modular configuration means that the system is the most scalable available, offering the ability to perform from one to eighty Xpert tests at the same time.

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WHO recommends testing with Xpert

MTB/RIF • In December 2010, the World

Health Organization (WHO) endorsed the Xpert MTB/RIF for use in TB endemic countriesThis test, and others that are likely to follow, could have the potential to improve the diagnosis of TB in those that are likely to be missed by traditional tests.

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WHO’s 2013 policy recommendations

• Using Xpert MTB/RIF to diagnose pulmonary TB and rifampicin resistance in adults and children Xpert MTB/RIF should be used rather than conventional microscopy, culture and DST as the initial diagnostic test in adults suspected of having MDR-TB or HIV-associated TB (strong recommendation, high-quality evidence).

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Changing Recommendation on

Tuberculosis Diagnosis

• Xpert MTB/RIF should be used rather than conventional microscopy, culture and DST as

the initial diagnostic test in children suspected of having

MDR-TB or HIV-associated TB).

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Xpert MTB/RIF Preferred than Microscopy

• Xpert MTB/RIF may be used rather than conventional microscopy and culture as the initial diagnostic test in all adults suspected of having TB (conditional recommendation acknowledging resource implications, high-quality evidence).

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Xpert MTB/RIF may be used as a follow-on test to microscopy

• Xpert MTB/RIF may be used as a follow-on test to microscopy in adults suspected of havingTB who are not at risk of MDR-TB or HIV-associated TB, especially when further testing of smear-negative specimens is necessary (conditional recommendation acknowledging resource implications, high-quality evidence).

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The world is benefited with MTB/RIF Tests

• As of 2016, more than 23 million Xpert MTB/RIF tests have been procured in 130 countries and multidrug-resistant TB (MDR-TB) detection has more than tripled.4,5 However, sensitivity of Xpert MTB/RIF is imperfect in smear-negative and HIV-associated TB, and some limitations also remain in the determination of rifampicin-resistance status using the existing test. Ultra is a second-generation test that was designed to overcome the sensitivity limitations of Xpert MTB/RIF.

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Need for New Generation of Testing methods

• However, sensitivity of Xpert MTB/RIF is imperfect in smear-negative and HIV-associated TB, and some limitations also remain in the determination of rifampicin-resistance status using the existing test. Ultra is a second-generation test that was designed to overcome the sensitivity limitations of Xpert MTB/RIF.

LAUNCH OF NEW TB TEST ULTRA BACKED BY WHO

RECOMMENDATION2017

Xpert® MTB/RIF Ultra

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Xpert® MTB/RIF Ultra • It was developed by Cepheid in

collaboration with Rutgers, with additional support from the U.S. National Institute of Allergy and Infectious Diseases (NIAID), and FIND, with support from funders including the Governments of Australia and the Netherlands, and UK Aid from the British People.

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Xpert® MTB/RIF Ultra (Ultra), • Sunnyvale, CA, USA; New Brunswick, NJ, USA; Geneva, Switzerland

– 24 March 2017 – On World TB Day, Cepheid, Rutgers New Jersey Medical School and FIND announced a new version of the Xpert MTB/RIF test, the Xpert® MTB/RIF Ultra (Ultra), for the diagnosis of TB and rifampicin resistance. The World Health Organization (WHO) earlier today issued a recommendation that Ultra can be used as an alternative to the existing Xpert MTB/RIF test for the diagnosis of TB and detection of rifampicin resistance in all settings

Current Recommendation of WHO

• The World Health Organization (WHO) earlier today issued a recommendation that Ultra can be used as an alternative to the existing Xpert MTB/RIF test for the diagnosis of TB and detection of rifampicin resistance in all settings

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The WHO expert evaluation concluded that the new Ultra test showed better performance than

Xpert MTB/RIF • The WHO expert evaluation

concluded that the new Ultra test showed better performance than Xpert MTB/RIF in detecting TB in difficult-to-diagnose and vulnerable populations, such as children and people living with HIV, and in those with extra-pulmonary TB.

Xpert® MTB/RIF Ultra (Ultra),performance assessment

• Ultra’s performance was assessed in 2016 in a multi-centre non-inferiority study at ten sites in eight low- and middle-income countries. The study was coordinated by FIND, and conducted by FIND and the NIAID-sponsored Tuberculosis Clinical Diagnostics Research Consortium,.

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Xpert MTB/RIF Ultra assay proving to be a better technology

• The Xpert MTB/RIF Ultra assay was redesigned to boost analytical sensitivity more than ten-fold and to improve reliability of detecting mutations associated with rifampin resistance. The latter was accomplished by introducing a new and powerful feature, automated post-PCR melt curve analysis, to the GeneXpert System

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Xpert® MTB/RIF Ultra (Ultra), has higher sensitivity

• The study found that Ultra sensitivity was up to 17% higher than Xpert MTB/RIF, with the greatest sensitivity gains seen among patients that would have been missed in microscopy centres (smear-negative, culture-positive patients) and HIV-positive TB patients. In addition, several retrospective studies conducted in parallel to the main study demonstrated significant increases in sensitivity of TB detection in children and patients with extrapulmonary TB.

Xpert® MTB/RIF Ultra (Ultra), higher performance

•Ultra performance approaches that of liquid culture, but is faster and easier to use at the point of care,”, Rutgers New Jersey Medical School, whose research laboratory contributed to the development of the test.

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Increased sensitivity causes False Positives • As a result of its increased

sensitivity, the use of Ultra also resulted in a higher rate of false positives compared to Xpert MTB/RIF, possibly due to the detection of non-viable TB bacteria that are present in people with a recent history of TB

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Opinion of WHO Expert

Group • The WHO expert group

noted the need for further discussion on the implementation challenges this presents and the willingness to balance increased test sensitivity with decreased specificity in different settings.

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Observation of WHO

• Our expert group consultation found that Ultra performs better than its predecessor in the most difficult cases, such as in children and in patients with HIV co-infection or extra-pulmonary TB.

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WHO CAUTIONS ON NEWER

TECHNOLOGY • “The decreased

specificity of the test will require a more nuanced approach in diagnostic algorithms, and we encourage additional research on Ultra to inform its introduction and use.”

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WE ALL CAN WORK TO STOP TUBERCULOSIS

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Reference and Adopted from • 2017 LAUNCH OF NEW TB TEST ULTRA BACKED BY WHO RECOMMENDATION FIND• WHO RESOURCES ON TUBERCULOSIS AND NEWER CHALLENGES

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Program created by Dr.T.V.Rao MD for benefit of Medical and paramedical

professionals on global education on health care matters

Emaildoctortvrao@gmail.com

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