New TB Diagnostics Pamela Hepple Laboratory Specialist MSF-UK August 2013
Plan Focus on Xpert® MTB/RIF and the Hain MTBDRplus
systems Implementation of Xpert by MSF globally and in Myanmar The role of line probe assays in TB diagnosis The tuberculosis diagnostic test pipeline
Xpert® MTB/RIF • Multicentric study (Boehme, 2010) • MTB detection (one sample) • Sensitivity: • 92.2% for all patients • 72.5% for smear-negative patients • Specificity: • 99.2% • Rifampicin resistance (allows presumptive MDR diagnosis) • Sensitivity: 97.6% • Specificity: 98.1% (->100% when sequencing used to resolve discordance)
Source: http://who.int/tb/laboratory/mtbrifrollout/en/
DistributionMSF of Projects Xpert速 MTB/RIF sites Ukraine (Donetsk)
02
High MDR >10% Uzbekistan (Chimbay, Nukus)
Grozny, Russian Federation Abkhazia
Kyrgyzstan (Bishkek, Osh)
Myanmar (Yangon) Ethiopia (Dire Dawa) South Sudan (Loki)
Tajikistan (Dushanbe) India (Manipur) Cambodia (Kampong Cham)
Colombia CAR (Zemio)
Uganda (Arua)
DRC, Kinshasa
Somalia (Galcayo) Kenya (Mathare, Kibera, Homabay) Malawi(Chiradzulu, Thyolo) Mozambique (Moatize, Mavalane)
Zimbabwe(Birchenough, Murambinda,Epworth, Gutu, Gokwe)
Swaziland (Nhlangano, Hlatikulu, Mankayane, Matsapha , Matsanjeni)
SA (Eshowe, Mbongolwane)
Lesotho (Roma)
High MDR Low MDR
High HIV
Low HIV
8 9 17
7 1 8
Total 15 10 25
High HIV > 1%
Xpert® MTB/RIF relative gain vs microscopy Fluorescence microscopy
Ziehl–Neelsen
130% 115%
120%
110%
110% 95%
100% 90% 80% 70%
62%
60% 50% 40% 30%
57%
51%
73%
72%
72%
69%
74%
56%
48% 23%
10%
20% 10% 0%
Sm+ Xpert+ Relative gain
• Relative gain varies from 10% to 115% • Relative gain: 38.3% vs. FM and 90.6% vs. ZN
56%
69%
Frequency of inconclusive results • Out of 36,540 samples tested, 2,461 (6.7%) gave inconclusive results, with large variation between projects: median of 5.3% (range 0-17%) At least 11 faulty modules were replaced • Only 7/25 sites had inconclusive results ≤ the 3% benchmark • An improvement over time has been observed, with the rate of inconclusive results decreasing. Main factors contributing to this improvement are: i) Replacement of devices faulty modules ii) Introduction of new cartridge version (G4 cartridge)
MSF OCA Myanmar data March – December 2012
January – June 2013 Detected Not Indet. Total detected
Detected Not Indet. Total detected MTB
419
648
RIF
72
338
9
Inconcl.
1067
MTB
604
1001
419
RIF
88
508
21
Inconcl.
1605 11
607 70
Data is for Xpert used as a first-line test for Yangon MSF TB
suspects, and MDR suspects from non-Yangon project sites Inconclusive results: 2012 - 21/1067 (2%); 2013 – 70/1605 (4%)
XPERT MTB/RIF: lab feasibility aspects •Relatively easy to use but not «plug and play» device : training is essential
•Substantial logistical and financial investments required in particular for implementation at decentralized level : -stable power supply -air conditioning to maintain operating temperature at < 30 C - Example of start-up cost from MSF site in Mozambique: 25,000 euro excluding cost of cartridges •Turn-around-time (TAT) to result: -Most of the projects reported a TAT of 1-3 days. -The TAT is longer when specimens are being sent from one facility to another for testing. In order to decrease TAT, investments are required in: - specimen transport (incl. cold chain) - transmission of the Xpert result (preferably electronically)
XPERT MTB/RIF: CONSIDERATION FOR SCALE-UP •
DIAGNOSIS: Essential to not address Xpert MTB/RIF in a vacuum but to make sure a full and effective “package” for TB diagnosis is implemented and supported - Infrastructures upgrade - Transport and cold chain - Training (for lab staff and for medical staff) - Lab capacity for confirmatory test and full DST available - More active case detection strategies – outreach testing, use of lay health workers will improve case finding (especially mobile-based community testing)
Need for rapid DST beyond rifampicin- culture and phenotypic DST too challenging and slow
Current algorithms in use in Myanmar
Dx of MDR-TB
TAF-1, TAF-2, TAD, Relapse, Relapse-suspect, MDR-Contact with TB symptoms Facility with Xpert MTB/RIF
Facility that can refer to facility with Xpert MTB/RIF
Facility with no access to Xpert MTB/RIF Sputum for AFB Chest X-ray
Xpert MTB/RIF
No TB
Appropriate further clinical management
TB, No R-res
TB, R-res
TAF-1, TAF-2 TAD, Relapse
MDR Contact
Enrol on Cat 2
Enrol on Cat 1
DST
MDR-TB treatment
Manage as per DOTS guidelines
HIV-positive TB suspect
Dx of (MDR)TB in HIV+ TB suspect
Facility with Xpert MTB/RIF
Facility that can refer to facility with Xpert MTB/RIF
Facility with no access to Xpert MTB/RIF
Sputum for AFB Sputum for AFB Chest X-ray
AFB-pos/neg
Xpert MTB/RIF
TB, R-res
Xpert MTB-/RIFPTB unlikely
TB, No R-res TAF-1, TAF-2 TAD, Relapse
Assess for EPTB New
No EPTB
EPTB
DST MDR-TB treatment CPT - ART
Cat. 2 treatment CPT - ART
Cat 1 treatment CPT - ART
Investigate/treat for other disease / Reassess for TB if no improvement
Manage as per DOTS and TB/HIV guidelines
TB suspect
HIV-neg No risk for MDR
Facility with Xpert MTB/RIF
Facility that can refer to facility with Xpert MTB/RIF
Facility with no access to Xpert MTB/RIF
Sputum for AFB AFB-negative
Sputum for AFB
AFB-positive AFB-negative
Chest X-ray Normal
AFB-positive
Abnormal
Xpert MTB/RIF No TB
Investigate/treat for other disease / Reassess for TB if no improvement
TB, No R-res
Cat.1 treatment or Cat.2 treatment
TB, R-res DST MDR-TB treatment
Manage as per DOTS guidelines
Myanmar diagnostic algorithms Xpert MTB/RIF is present in Myanmar diagnostic algorithm – first test for
MDR suspects and/or HIV+ Can treat for MDR only after phenotypic confirmation (unless HIV+ or very ill patient) – no empirical treatment based on Xpert results for routine patients. Can do Hain test on SM 2+/3+ and if rifampicin resistance confirmed, and isoniazid resistance detected, can start MDR treatment In all cases, confirm rifampicin resistance with phenotypic DST– if discordant, repeat; if remains discordant, go with culture result (reference standard) Treatment is delayed if have to wait for phenotypic results It is possible to get Xpert Rif-resistant/phenotypic Rif-sensitive results – some
evidence is emerging that the Xpert results may be true positives (van Deun 2013). Further evidence is required as genotypic testing becomes more widespread.
Role of Hain Genotype MTBDRplus and sl Source:
Hain MTBDRplus test Endorsed by WHO in 2008 for use
on smear-positive sputum, and isolates. Version 2 test is not endorsed by WHO for smearnegative samples. Technically-demanding, so based mostly in reference labs Detects rifampicin and isoniazid resistance – can diagnose MDR TB Can be automated for high through-put Second-line test is now available.
http://www.finddiagnostics.org/media/n ews/080227.html
The TB diagnostics pipeline Feasibility and proof of principle Seek TB Reference level
District, Subdistrict, microscopy
Evaluation studies
Abbott NAAT
TREK Sensititre
BD Max NAAT
NIPRO (LPA)
Qiagen (China) Colorimetric TLA (DST)
Epistem Genedrive
NAA based assays Alere Q
Ustar Biotechnologies EasyNatTB
Twist Dx; IonianTechn; Biohelix Techn; Enigma; Wave 80; NorthWestern Univ.
Antibody detection (MBio) Peripheral level
Development optimization (design lock)
Beta-lactamase assay (GlobalBio Diagnostics) VOC based assays
Demonstration studies
P O L I C Y
Hain Genotype MTBDR sl TB-LAMP (completed)
TrueNAT MTB
Alere Determine LAM (completed) Culture based test NAA based test FIND is a co-sponsor
Fast-Follower technologies for NAA-based test
_
+ + _ + ? Adapted from :TB Diagnostic Technology Landscape. Semiannual Update. UNITAID. December 2012
Gates Foundation Next Generation Programme â&#x20AC;˘
To support the development of a low-cost, nucleic acid amplification based test suitable for implementation at microscopy level - First platform selected: AlereQ* - Alere Q HIV Viral load test on late stage of development - Gates Foundation provided a USD 21.6 M grant to support development of a TB diagnostic assay for detection of TB and drug resistance - Very early stage - Looking at Urine and sputum as sample types Expected timelines: 24-36 months
*http://www.alere.com/content/dam/alere/docs/pressreleases/Gates_Grant_Relea se_Alere_FINAL_19_FEB_v2.pdf
Conclusion Xpert can increase case detection and get patients onto second
line treatment faster than culture and DST Use of Xpert rifampicin resistance results can place people on empiric MDR treatment quickly – specificity is generally very high The Hain first-line test can add isoniazid information and is useful for MDR screening purposes; the second-line test lacks sensitivity at present Promising new diagnostics in the pipeline are focused on molecular techniques Swift access to second line testing is important for tailored second-line treatment regimens and detection of pre-XDR and XDR tuberculosis