A rapid diagnostic test deployed in high-burden settings such as public health clinics may help fight multidrug-resistant tuberculosis (MDR-TB), which is increasingly on the rise and infiltrating vulnerable communities hit by HIV and poverty.
A study in the first April issue of the American Journal of Respiratory and Critical Care Medicine found that using a molecular assay test instead of conventional culture techniques may revolutionize the diagnosis and reporting of MDR-TB in the high-infection areas by delivering critical results more quickly, which may enable prompt treatment.
A barrier to appropriate treatment is the lengthy diagnostic process of conventional techniques, which is not well suited to public health settings serving vulnerable populations.
TB is the leading cause of death among AIDS patients worldwide. The association is particularly lethal when drug-resistant TB is being transmitted. MDR-TB, with resistance to the most important anti-TB drugs, isoniazid and rifampicin, is even more lethal.”
The study took place in a national health laboratory in Cape Town, South Africa, which serves more than 4.2 million people and processes some 400,000 specimens annually. The testing was performed on residual portions of specimens originally collected for other purposes. Interpretable results were obtained within 1 to 2 days in 97% of smear-positive samples, and had a better than 98 percent specificity and sensitivity rate for multidrug resistance.
The two to three months that conventional techniques can take to determine drug resistance can be fatal to an HIV-infected patient. Complicating the picture is the looming threat of MDR-TB becoming XDR-TB—extensively drug resistant.
