Tuberculosis Rapid Test Allows In-the-Field Results

Northwestern Engineering researchers have developed a new way to quickly test for tuberculosis that avoids several pitfalls of other methods. 

The new test works with the existing DASH (Diagnostic Analyzer for Specific Hybridization) Rapid PCR System, a device previously developed at Northwestern that can run testing at point of care. The test detects Mycobacterium tuberculosis (MTB), the bacteria that cause tuberculosis, from a simple specimen swabbed from the tongue swab or sputum—the thick mucus made in lungs and airways. 

Because results can be rapidly attained in the field, the system enables patients in remote areas who lack access to traditional medical offices to receive testing and care in a single medical visit. 

The study was published Nov. 12 in the journal Open Forum Infectious Diseases. 

“Diagnosis is the weakest link in tuberculosis care. Tuberculosis diagnosis can be complex and time consuming,” said Northwestern’s Sally McFall, the study’s corresponding author. “Bacterial culture is the gold standard. It has high sensitivity, but the time-to-result is lengthy, and it is technically challenging and prone to contamination.”

Current testing requires sputum that offers the highest tuberculosis bacteria load, considered the “gold standard” for testing. Many patients, however, cannot produce enough sputum to test, so researchers pursued testing via tongue swab to offer another rapid result option.

McFall is a research professor of biomedical engineering at the McCormick School of Engineering and the co-director for the Center for Innovation in Global Health Technologies (CIGHT), which developed both the DASH system and the new MTB test. DASH MTB is the latest diagnostic from McFall’s research team, which previously developed rapid point-of-care tests for COVID and hepatitis C.

This work is the culmination of long-standing collaborations with the University of Washington, the University of Cape Town, and Stellenbosch University. 

The World Health Organization reported 1.23 million people died from tuberculosis in 2024 alone. The hardest hit communities tend to live in impoverished areas with lower access to testing and treatment, as well as higher risk factors, including less access to housing or nutrition. 

A sputum sample is produced through coughing, and tuberculosis is spread through infected air droplets that can linger in the air for hours, thus potentially infecting health care workers and other patients. 

“Sputum is the preferred specimen for tuberculosis diagnosis, but up to one-third of patients cannot produce sputum and thus cannot be diagnosed,” McFall said. “Here, we tested using tongue swab specimens in addition to sputum and showed high sensitivity and specificity with both specimen types using a test that could provide the result within the clinic visit.”

A tongue swab specimen can be collected from nearly everyone, and the procedure can be done with minimal training, making it optimal for areas that lack access to laboratory testing. Non-lab personnel perform three simple steps to process the patient sample and then load the test cartridge into the analyzer for automated detection. The cartridge demonstrated storage stability in temperatures up to 113 degrees Fahrenheit (45 degrees Celsius), which is especially beneficial in areas that lack consistent access to electricity, refrigeration and air conditioning. 

The study found the rapid test’s performance matched the performance of Cepheid’s the Xpert MTB/RIF Ultra test, the most widely adopted molecular test for tuberculosis. DASH MTB reached 100 percent accuracy on true negative tests and 91 percent accuracy on true positive test results. 

“Tuberculosis is the leading cause of death from an individual infectious agent,” McFall said. “A rapid and sensitive test such as the DASH MTB assay could facilitate same day diagnosis and treatment.”