Simple, phage-based (FASTPplaque) technology to determine rifampicin resistance of Mycobacterium tuberculosis directly from sputum

Abstract

Setting: Cape Town, South Africa.

Objective: To evaluate the performance of a simple, manual, phage-based test for determining rifampicin (RMP) resistance of Mycobacterium tuberculosis directly from smear-positive sputum specimens.

Design: A comparative study of the performance of the FASTPlaque (phage amplification) technology to determine RMP resistance directly from smear-positive sputum compared with isolation and the conventional indirect Middlebrook 7H11 agar proportion method.

Results: The FASTPlaque direct RMP test achieved sensitivity, specificity and overall accuracy of 100% (11/11), 100% (134/134) and 100% (145/145), respectively, compared with the conventional indirect susceptibility test method (resolved data). The FASTPlaque direct RMP test reported results within 2 days from receipt of the specimen, while the conventional method took between 27 and 103 days (mean +/- SD 33.2 +/- 7.2 days).

Conclusion: FASTPlaque technology applied directly to smear-positive sputum offers performance comparable to conventional methods, with results available in 2 days instead of weeks to months. The test may form a useful part of DOTS-Plus programmes to combat multidrug-resistant tuberculosis, improving patient prognosis and reducing ongoing transmission of disease. It does not require specialised equipment, making it appropriate for high-burden countries.