Report of an Expert Consultation on the Uses of Nucleic Acid Amplification Tests for the Diagnosis of Tuberculosis

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Molecular Drug Susceptibility Tests (DSTs)

The expert panel also addressed available information on molecular tests for determining drug susceptibilities of M. tuberculosis bacteria directly from clinical specimens. Two well-characterized, CE-marked molecular DST kits are commercially available in Europe and elsewhere. (The CE marking, “Conformite Europenne,” certifies that a product has met European Union requirements.) The World Health Organization has recommended the use of these tests as screening tests for multidrug-resistant (MDR) TB. Although several laboratories in the U.S. offer molecular DSTs as ASR tests, none have been approved by the FDA.

The expert panel considers molecular DSTs to be an urgent public health and diagnostic need, because extensively drug-resistant (XDR) TB and MDR TB are becoming more prevalent globally. Such molecular DSTs should be available to all U.S. TB programs. The expert panel endorses the recommendations under consideration in the proposed American Thoracic Society ‘Diagnostic Standards and Classification of Tuberculosis in Adults and Children’ which supports the use of molecular methods for detection of drug resistance directly in AFB-smear positive sputum sediments for TB patients who have factors predictive of drug resistance.