Recent Advances in

Diagnosis of Tuberculosis

Dr. Muhammad Yahya NooriAssistant Professor

Department of Pathology

DIMC

Focal Person for Provincial Tuberculosis Reference Lab Sindh

DUHS

Tuberculosis

Second only to HIV/AIDS

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The Cost

2013

1.5 Million Deaths

9 Million New Cases

Drug Sensitive TB

$100-500/case

MDR TB

$9000-48000/case3

Pakistan

Burden of Disease

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Pakistan

New Cases

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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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Interferon Gamma Release Assay

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•QuantiFERON®-TB Gold

•T-SPOT®.TB test

Interferon Gamma Release Assay

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Fluorescent Microscopy

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Decontamination (in non sterile samples)

Culture in the adequate media

Culture in solid and liquid media

DST

Growth in solid media

Slow: 15d-2mDivision time 18h

Growth in liquid media7-42d

Inoculums!!

Identification Classical and Molecular

methods

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Xpert MTB/RIF Assay

Satisfactory results were obtained in the studies

that were performed in 2010:

• Sensitivity in smear-positive culture-positive specimens:

99%

• Sensitivity in smear-negative culture-positive specimens:

90%

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WHO Evaluation on Xpert MTB/RIF Assay-2011

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

DNA

or 131 cfu/ml sputum

(10-100 cfu/ml sputum for culture)

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WHO Evaluation on Xpert MTB/RIF Assay-2011

• Average detection time:– Solid culture: >30 days

– Liquid culture: 17 days

– Microscopy: 1 day

– Xpert MTB/RIF: <1 day

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Processing

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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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Current Practices

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Thank you

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