Quick Test for Rifampin-Resistant TB Shows Promise
Major Finding: A new automated assay designed for use in the field in Third World regions had 98% sensitivity and 99% specificity at detecting TB infection, and accurately identified susceptibility of M. tuberculosis to rifampin. The device analyzes untreated sputum samples directly and delivers results within 2 hours with minimal hands-on time.
Data Source: A multicenter, prospective study of 1,730 residents of South Africa, Peru, India, and Azerbaijan who were suspected of having TB.
Disclosures: The study was designed and supervised by FIND, the sponsor (and maker of the Xpert MTB/RIF), with additional development support provided by the National Institutes of Health, Cepheid, and the Bill and Melinda Gates Foundation. The investigators reported no additional disclosures.
From the New England Journal of Medicine
The assay is “simple to perform with minimal training, is not prone to cross-contamination, requires minimal biosafety facilities, and has a high sensitivity in smear-negative TB (the last factor being particularly relevant in patients with HIV infection),” they noted (N. Engl. J. Med. 2010 Sept. 1 [doi:10.1056/NEJMe1008496]).
However, “because Boehme et al. used the test at reference laboratories, their study offers only indirect proof of concept for use in [other] settings. Critical to rapid scale-up of the test will be the results of additional studies to determine how it performs in such settings and whether its use improves outcomes for patients in a cost-effective manner,” Dr. Small and Dr. Pai added.
“If an improved rapid nucleic acid amplification test is adopted globally, it could help avert more than 15 million TB-related deaths by 2050,” they noted.
Dr. Small is at the Global Health Program of the Bill and Melinda Gates Foundation and the Institute for Systems Biology, both in Seattle. Dr. Pai is in the department of epidemiology and biostatistics at McGill University and at Montreal Chest Institute.
