An assessment of nucleic acid amplification testing for active mycobacterial infection

Marketing status of device

NAAT for the detection of mycobacteria may be an in-house assay or a commercial kit. In December 2010 the WHO endorsed the Xpert assay for the rapid and accurate detection of MTB and rifampicin-resistant MTB. This test was approved by the TGA in April 2013 and by the U.S. Food and Drug Administration in July 2013.

Summary of TGA approval⁷ for the IVD Class 3 GeneXpert MTB/RIF assay:

ARTG entry number: 207732

Sponsor: Cepheid Holdings Pty Ltd

Intended purpose: The GeneXpert MTB/RIF assay for use with the Cepheid GeneXpert system is a semi-quantitative, nested real-time PCR in-vitro diagnostic (IVD) test for the detection of:

• 
  MTB-complex DNA in sputum samples or concentrated sediments prepared from induced or expectorated sputa that are either AFB smear positive or negative
  
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  rifampicin-resistance associated mutations of the rpoB gene in samples from patients at risk for rifampicin resistance
  

The GeneXpert MTB/RIF assay is intended for use with specimens from untreated patients for whom there is clinical suspicion of TB.

No other commercially available NAATs for the detection of MTB and/or NTM are approved by the TGA.

An in-house NAAT for the detection of MTB is classified as a Class 3 IVD medical device by the TGA. IVDs are pathology tests and related instrumentation used to carry out testing on human samples, where the results are intended to assist in clinical diagnosis or in making decisions concerning clinical management. From 1 July 2014 all IVDs must comply with a set of essential principles for their quality, safety and performance. Laboratories that manufacture Classes 1–3 in-house IVD medical devices must comply with the requirements of Part 6A, Schedule 3, of the Regulations (Therapeutic Goods Administration 2011).

To meet these requirements the laboratory must be accredited as a medical testing laboratory by either the National Association of Testing Authorities or a conformity assessment body determined suitable by the TGA, and meet the National Pathology Accreditation Advisory Council (National Pathology Accreditation Advisory Council 2014) performance standard requirements for the development and use of in-house IVDs (Therapeutic Goods Administration 2012). The Guidelines for Australian mycobacteriology laboratories (National Tuberculosis Advisory Committee 2006) also state that these requirements must be met.