Advances in Diagnostic Assays for Tuberculosis

Abstract

Approximately one-third of the global burden of tuberculosis (TB) remains undiagnosed each year and the vast majority of cases of multidrug-resistant TB remain undetected. Many countries still place heavy reliance on outdated technologies that are blunt and ineffective tools for controlling this epidemic. However, during the past 10 years, there has been substantial progress within the TB diagnostics developmental pipeline. Old technologies have been reviewed and improved and new technologies have been developed and evaluated and are now being implemented. This review summarizes these developments and describes the currently available diagnostic tools. Consideration is given to the requirements of future diagnostic tests and how these should be evaluated not only with regard to their diagnostic accuracy and operational feasibility, but ultimately in terms of whether they impact clinical outcomes cost effectively, especially for those most in need.

Figure 1.

Schematic showing the sequential steps of the Xpert MTB/RIF assay test procedure. SR, sample reagent; PCR, polymerase chain reaction. (Figure reproduced from Lawn and Nicol 2011, with permission from the authors.)

Figure 2.

Photograph of a Determine TB-LAM Ag lateral flow test strip. Urine (60 µL) is applied to the sample pad, and after 25–35 min of incubation at room temperature, the control band is checked and the sample test result is read with comparison to the reference card. The presence of a band of sufficient intensity in the sample window indicates the presence of lipoarabinomannan (LAM) in the urine, providing a rapid diagnosis of tuberculosis. (Figure reproduced from Lawn 2012, with permission from the author.)