報告人:蔣佳蓉
報告日期:101.05.08
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Introduction
Reference
Purpose
Material and Method
Discussion
Introduction
Mycobacterium tuberculosis is a member of the
Mycobacterium tuberculosis complex (MTBC) of bacteria that
cause human and animal tuberculosis.
Bacteriological examination, such as culture or identification of the
mycobacterium species, also plays an important role to provide
clinical diagnosis. However, a conventional culture method, L-J
medium, takes 4 to 5 weeks because the bacillus divides every 16 to
20 hours, an extremely slow rate compared with other bacteria.
Therefore, Centers for Disease, Taiwan, recommends that TB
laboratories should develop rapid technique
New Cases of TB, by Country, 2006
10 million cases projected for 2010
WHO Report 2008
Reference
GeneXpert MTB/RIF
GeneXpert MTB/RIF 操作環境 :只需要低度 TB 感染風險實驗室
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NEJM – September 2010
Key publication
Mario Raviglione世衛組織遏制結核病司
司長表示:
•
…These Xpert MTB results suggest that
it has the potential to revolutionize TB
care, and WHO will treat it, as a top
priority.”
Catharina C. Boehme: Rapid Molecular Detection of Tuberculosis and Rifampin Resistance, ENJM 2010
PAGE | 9
FIND: Funding Foundation for Innovative New Diagnostics - Lancet publication
Aim:
 But no performance data exist from district and
subdistrict health facilities in tuberculosis-endemic
countries.
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We aimed to assess operational feasibility, accuracy,
and effectiveness of implementation in such settings.
Lancet, Published online April 19, 2011 DOI:10.1016/S0140-6736(11)60438-8
Conventional methods
Xpert + conventional
Time to therapy (median days)
Conventional
Xpert
Smear
Positive
4
2
Smear
negative
56
5
Studied >1,700 Patients
• Peru, Azerbaijan, South Africa and India
Testing Locations
Baku,
Azerbaijan
Mumbai,
India
Lima,
Peru
Cape Town,
South Africa
Durban, South
Africa
Catharina C. Boehme: Rapid Molecular Detection of Tuberculosis and Rifampin Resistance, ENJM 2010
FIND: Funding Foundation for Innovative New Diagnostics - Lancet publication
Median time to detect
MTB:
Median time to Drug
resistance
Xpert
MTB/RIF
0 days
Xpert
MTB/RIF
0 days
(IQR 0–1),
microscopy
1 day (1-2)
line-probe
assay
20 days
(10–26)
solid culture
30 days
(IQR 0–1),
(23–43)
liquid culture
conventional 106 days
drug(30–124)
susceptibility
testing
16 days
(13–21)
Lancet, Published online April 19, 2011 DOI:10.1016/S0140-6736(11)60438-8

晶宇（DR. Chip Biotechnology Inc.）

亞洲基因（AsiaGen Corporation）
Purpose:
MTBC及RIF抗藥性診斷
The challenge of current MTB testing
•Current Nucleic Acid Amplification methods:
•Very sensitive on culture:
•For identification
•No commercial qPCR for testing MDR-TB yet
•Time consuming and requiring highly skilled personnel
•Not optimal on clinical samples:
•Until now not so sensitive on smear negative samples
•Bio-Safety Level requirement for MTB testing (CDC)
• from P2 plus to P3
• The cost to establish and maintain a P3 lab are very expensive
PAGE | 16
Diagnostic
s
4-6 weeks
Clinical judgement
Patient
management
Day 1-3
Culture (liquid and solid)
3 Smear tests
Identification : TB, other
mycobacteria…
TB- : Patient released
TB- / TB+ confirmed
TB+:
MDR TB or XDR TB:
1st line therapy initiated
Therapy modified with 2nd
/ 3rd line drugs
+/- confirmation by PCR
No drug susceptibility
Smear- TB: patient released
Smear+ TB: patient
hospitalized and isolated
Drug susceptibility testing
Patient placed in a negative
pressure room if available
Specimen Processing is Required for NAATs
BSL2~3
Real-Time PCR
DNA extraction
2 hrs (batched)
Material and method
1. Material ：sputum(decontamination) from Genotype
2. Method：GeneXpert
The Solution:
Cepheid Xpert MTB/RIF
(WHO endorsed )
MTB &RIF in 100min
Cepheid GeneXpert® MDx System
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System features
• One step PCR- Fully automatic
• Highly reproducibility and sensitivity &
specificity
• No need for skilled technician and special
labs !!
Patient
management
Diagnostic
s
Day 1-3
Clinical judgement
1-3 Smear tests
Xpert MTB/RIF:
4-6 weeks
Culture (liquid and solid)
Identification : TB, other
mycobacteria…
Smear+ / smear- TB
confirmed
Drug susceptibility testing
TB: Patient
released
Rifampicin
resistance
TB- / TB+, MDR TB confirmed
TB+:
XDR TB:
1st or 2nd line therapy initiated
Therapy modified
Patient released or admitted
Patient placed in a negative
pressure room if available
Isolation in regular or negative
pressure room
Culture
Positive
Culture
Negative
Smear
Positive
Culture
Positive
70
5
275
7
289
0
Smear negative
Xpert
Positive
Xpert
Negative
• Sensitivity in smear negative, culture positive (S-C+) was 90.9%
(70/77)
• Sensitivity in smear positive, culture positive (S+C+). was 100%
(275/275)
• Specificity of the assay was 98.3%
• Sensitivity observed for Rifampicin resistance was 96.7%
• Specificity observed for Rifampicin resistance was 98.6%
Xpert MTB/RIF Analytical Studies
•
Analytical Sensitivity of approximately approx 131
cfu/ml (Smear 10,000 cfu/ml)
•
Specificity tested with high concentrations of MOTT
(Mycobacteria Other Than Tuberculosis)
•
No evidence of amplicon cross-contamination
(cartridge)
•
Perfect score on QCMD TB Proficiency Panel
(QCMD: a leading International External Quality
Assessment (EQA) organization)
PAGE | 27
Sensitivity
All Culture
Positive
Specificity
Smear and Culture
Positive
Smear Negative
Culture Positive
Overall
97.6%
99.8%
90.2%
98.1%
Lima
99.1%
100%
83.3%
100%
Baku
96.6%
100%
92.8%
97.1%
Cape Town
95.9%
99.0%
90.4%
98.4%
Durban
95.6%
100%
86.7%
97.3%
Mumbai
98.4%
100%
88.5%
97.2%
Catharina C. Boehme: Rapid Molecular Detection of Tuberculosis and Rifampin Resistance, ENJM 2010
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Xpert MTB/RIF combines rapidity and high
sensitivity in a simply performed test
Xpert MTB/RIF detects simultaneously the
tuberculosis complex and rifampicin resistance
Xpert MTB/RIF significantly enhances diagnosis
and therapeutic decision making in pulmonary
tuberculosis
Sensitivity
Specificity
Overall
99.1%
100%
Lima
100%
100%
Baku
98.1%
100%
Cape Town
93.8%
100%
Durban
100%
100%
Mumbai
99.2%
100%
After discrepant result resolution by sequencing
Catharina C. Boehme: Rapid Molecular Detection of Tuberculosis and Rifampin Resistance, ENJM 2010
MTB Positive Medium, Rif Resistance NOT DETECTED
PAGE | 31
MTB Positive Low, Rif Resistance DETECTED
PAGE | 32
MTB not detected
PAGE | 33
GeneXpert
Infinity-48
GX-XVI
GeneXpert®
Module
GX-I
GX-IV