Line Probe Assay: A New Arrival at the PRL

Dr. Muhammad Yahya NooriAssistant Professor

Department of PathologyDIMC

Focal Person for Provincial Tuberculosis Reference Lab Sindh

DUHS

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TuberculosisMost common infectious cause of Mortality

after HIV/AIDS

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The Cost2013

1.5 Million Deaths

9 Million New Cases

Drug Sensitive TB

$100-500/case

MDR TB

$9000-48000/case

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PakistanBurden of Disease

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PakistanNew Cases

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Drug Resistant Tuberculosis

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Case Notification in Pakistan

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Diagnosis of tuberculosis

Latent Infection Active tuberculosis

Smear examination

Solid and liquid culture

Identification

Susceptibility testing methods

TST

IFN- techniques

Molecular methods- Detection- Identification- Detection of resistance

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Xpert MTB/RIF Assay Meta-Analysis Study

• Average sensitivity for detection of rifampicin resistance: 94.1%

• Average specificity for detection of rifampicin resistance: 97.0%

• Average sensitivity in extra-pulmonary specimens: 80.4%

• Average specificity in extra-pulmonary specimens : 86.1%

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WHO Evaluation on Xpert MTB/RIF Assay-2011

• Xpert MTB/RIF assay:– Analytical sensitivity: 5 genome

copies/purified DNAor 131 cfu/ml sputum(10-100 cfu/ml sputum for culture)

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Simultaneous Detection of Rifampicin and INH Resistance

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Strip Reading

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For Smear Positive specimens:• Rifampicin:

Sensitivity >97%Specificity >99%

• In combination with INH: Sensitivity >90%Specificity >99%

Sensitivity and Specificity

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Thank you