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  • Rapid molecular detection of tuberculosis and rifampicin drug resistance: retrospective analysis of a national UK molecular service over the last decade

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Chest clinic
Audit, research and guideline update
Rapid molecular detection of tuberculosis and rifampicin drug resistance: retrospective analysis of a national UK molecular service over the last decade
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  1. N Seoudi1,2,
  2. S L Mitchell1,3,
  3. T J Brown1,3,
  4. F Dashti2,
  5. A K Amin2,
  6. F A Drobniewski1,2,3
  1. 1Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University, London, UK
  2. 2Department of Medical Microbiology, Barts and the London NHS Trust, London, UK
  3. 3National Mycobacterium Reference Laboratory, Health Protection Agency, London, UK
  1. Correspondence to Professor F A Drobniewski, HPA National Mycobacterium Reference Laboratory, Clinical TB and HIV Group, Blizard Institute, 2 Newark Street, London E1 2AT, UK; f.drobniewski{at}qmul.ac.uk

Abstract

Background Fast and reliable detection of Mycobacterium tuberculosis complex (MTBC) and drug resistance is crucial in establishing effective treatment and enforcing timely public health measures.

Methods The authors analysed the performance of a national UK molecular diagnostic service over a decade, based on the use of a line probe assay (Innolipa, LiPA) compared with conventional liquid and solid cultures with rapid molecular identification and culture-based drug resistance testing.

Findings Data were available for 7836 consecutive patient samples using LiPA and the reference microbiological technique (conventional liquid and solid cultures with rapid molecular identification and culture-based drug resistance testing). For all sputum specimens (n=3382) the sensitivity, specificity, positive predictive value, negative predictive value and accuracy for MTBC detection were 93.4%, 85.6%, 92.7%, 86.9% and 90.7%; the equivalent values for smear-positive sputum specimens (n=2606) were 94.7%, 80.9%, 93.9%, 83.3% and 91.3%. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for detection of rifampicin resistance in all sputum samples (n=1667) were 92.1%, 99.3%, 89.4%, 99.5% and 98.9%, respectively; the equivalent values for smear-positive sputum specimens (n=1477) were 93.3%, 99.3%, 87.5%, 99.6% and 99%. Between January 2006 and December 2008, LiPA saved 25.3 and 32.2 days for TB diagnosis and rifampicin resistance of smear-positive samples, respectively.

Interpretation A molecular diagnostic service, using a non-automated line probe assay approach, provides a rapid and reliable national service for diagnosing MTBC and rifampicin resistance.

  • Atypical mycobacterial infection
  • tuberculosis
  • viral infection
  • bacterial infection
  • pneumonia
  • atypical mycobacterial infection
  • respiratory infection

https://doi.org/10.1136/thoraxjnl-2011-200610

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    Footnotes

    • Funding The study was funded internally by the UK Health Protection Agency and Barts and the London School of Medicine, Queen Mary University.

    • Competing interests We declare that we have no conflict of interest. Specifically all the LiPA molecular and culture assays described were purchased at the normal price. All authors have completed the Unified Competing Interest form at http://www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; and no other relationships or activities that could appear to have influenced the submitted work.

    • Patient consent Uses routine data submitted on request form for TB diagnosis sent to our centre. Samples part of standard of care.

    • Ethics approval Uses routine data submitted on request form for TB diagnosis sent to our centre.

    • Provenance and peer review Not commissioned; externally peer reviewed.