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Xpert MTB/RIF March 2009. PAGE | 1 Agenda Background Current testings Xpert MTB/RIF product.

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Presentation on theme: "Xpert MTB/RIF March 2009. PAGE | 1 Agenda Background Current testings Xpert MTB/RIF product."— Presentation transcript:

1 Xpert MTB/RIF March 2009

2 PAGE | 1 Agenda Background Current testings Xpert MTB/RIF product

3 Background

4 PAGE | 3 Slow Progress in Fight Against Tuberculosis

5 PAGE | 4 Why is Progress Slowing Down? Insensitive or too slow diagnostic methods => transmission Emergence of drug resistant strains, MDR and XDR Only 2% of MDR-TB cases worldwide are being diagnosed and treated appropriately (WHO statement) Shortage of funding

6 Current tests

7 PAGE | 6 Common Laboratory Testing Algorithm

8 PAGE | 7 TB Smear Testing Time-to-result ~2 hrs Considerable hands-on-time Cheap Subjective Experienced technologists required

9 PAGE | 8 TB Smear Testing is Insensitive Sensitivity of smear testing is at most 70%. A minimum of 30% are smear-negative culture-positive 1 Approximately 20% of transmitted infections are caused by smear-negative / culture positive patients 2 Sources: 1:Long R, Smear-Negative Pulmonary Tuberculosis in Industrialized Countries, Chest 2001;120; :Behr MA, Warren SA, Salamon H, et al. Transmission of Mycobacterium tuberculosis from patients smear-negative for acid-fast bacilli, Lancet 1999; 353:444–449

10 PAGE | 9 TB Culture Testing Time-to-result: Solid culture: 6 weeks for a negative Liquid culture: 3 weeks for a negative Possibility to grow other Mycobacterium species Experienced technologists required

11 PAGE | 10 Some Characteristics of an Ideal TB test Direct-specimen detection of MTB Sensitivity of culture with goal of eliminating negative cultures Simultaneous detection of drug resistance On demand availability (no batching requirement) Decentralized platform technology to reduce or eliminate sample shipment Rapid (<2 hours) Portable Low skill requirement Highly reliable

12 Xpert MTB/RIF product

13 PAGE | 12 Cartridge Design and Operating Principle Sonicator Dome Rotary Valve Syringe Barrel RT-PCR Tube

14 PAGE | 13 Bead Format Reagents Target-specific reagent bead: primers; rpoB specific probes; controls Enzyme reagent bead: Taq polymerase; dNTPs; Buffers; Mg 2+ Sample Preparation bead: Bacillus globigii spores; excipients Retaining balls

15 PAGE | 14 Intended use of Xpert MTB/RIF The Xpert MTB/RIF Assay is intended for rapid detection of Mycobacterium tuberculosis complex and rifampicin resistance in adult patients in sputum specimens with clinical suspicion of tuberculosis. The assay is intended for use on smear-positive and smear-negative samples. The assay, performed in the Cepheid GeneXpert ® System*, is a semi- quantitative in-vitro diagnostic test The Xpert MTB/RIF assay is not intended for use in treatment monitoring. * N.B. Xpert MTB runs on GeneXpert system 6 colour with software version 2.1. only!

16 PAGE | min incubation Xpert MTB/RIF Protocol STR 2 min hands-on time to result = 1h45min

17 PAGE | 16 Molecular Beacon Target Hybrid The Xpert MTB/RIF Molecular Beacon Assay 5 Probes bind to wild type Probes do not bind to mutant sequence 1 Probe for SPC (B. globigii) 6 fluorescent dyes detected simultaneously A B C D E rpoB gene

18 PAGE | 17 Sputum… the final PCR frontier It is usually highly viscous and thus incompatible with microfluidic devices It is often purulent It is often bloody Target organisms require concentration in order to be consistently detected Complicated off-line centrifugation and DNA extraction too slow and technically demanding for decentralized testing

19 PAGE | 18 The solution for sputum Sample Treatment Reagent Liquidify sputum Inactivates Mtb in sputum by 6 – 7 logs

20 PAGE | 19 Xpert MTB/RIF Preliminary Analytical Studies Analytical Sensitivity of approximately approx 100 cfu/ml (Smear 10,000 cfu/ml) Specificity tested with high concentrations of MOTT (Mycobacteria Other Than Tuberculosis) No evidence of amplicon cross-contamination Perfect score on QCMD TB Proficiency Panel Mutation detection capability confirmed with isolate DNA and artificial targets having a global frequency reported at > 0.005

21 PAGE | 20 Preliminary Performance Characteristics N.B. Data to be changed in final package insert

22 PAGE | 21 Semi-quantitative results in Xpert MTB/RIF

23 PAGE | 22 Amplification plot – TB positive/Rif sensitive MTB Positive Medium, Rif Resistance NOT DETECTED

24 PAGE | 23 Amplification plots – TB positive/Rif resistance MTB Positive Low, Rif Resistance DETECTED

25 PAGE | 24 Amplification plot – TB not detected MTB not detected

26 PAGE | 25 Xpert MTB/RIF TB confirmation and therapeutic guidance in less than 2 hours More sensitive than smear, much quicker than culture Minimal technical expertise required

27 PAGE | 26 The test is: Available as from 2 nd Quarter 2009 Rapid, with results delivered in less than two hours High in sensitivity and specificity, for smear-positive and smear-negative samples A walk-away ease of use system: just insert pre- treated samples A closed cartridge; sample preparation, amplification and detection take place in the cartridge Detecting M tuberculosis and rifampicin resistance utilizing the rpoB gene

28 Acknowledgements UMDNJ, New Jersey, USA The Foundation for Innovative Diagnostics (FIND), Geneva, Switzerland Support: NIH grant: The Foundation for Innovative Diagnostics

29 Xpert MTB/RIF CE-IVD (10) Product code: GXMTB-10


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