Evaluation of GeneXpert MTB/RIF assay for detection of pulmonary tuberculosis on sputum samples

Objective: To analyse the diagnostic performance of MTB/RIF assay for the diagnosis of pulmonary tuberculosis and detection of rifampicin resistance using sputum samples

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Study Design: Observational cross-sectional study

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Place and Duration of Study: Provincial TB Reference Laboratory [PTRL], Hayatabad Medical Complex, Peshawar, Pakistan, from January to October 2015

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Methodology: A total of 268 participants were consecutively enrolled in the study after meeting the inclusion criteria. Their sputum samples were collected and processed by N-acetyl-L-cysteine-sodium hydroxide [NALC-NaOH] method and GeneXpert MTB/RIF assay

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Results: This study determined the overall sensitivity and specificity of MTB/RIF assay, it was 92.4% [86/93] and 97.1% [138/142], respectively. The sensitivity was 98.4% [60/61] in culture proven smear positive samples, whilst sensitivity in culture proven smear negative samples was 93.7% [30/32], using culture as reference standard

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Conclusion: GeneXpert MTB/RIF assay could greatly improve early diagnosis of PTB in smear negative cases as well as multidrug resistant tuberculosis