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Tuberculosis: Better Detection Techniques and Treatments for a Deadly Disease

Tuberculosis hides in plain sight.

By Donna Campisano, specialist, Communications, APHL

World TB Day is March 24

Before COVID-19 sprang on the scene, tuberculosis (TB) had the alarming distinction of being the world’s deadliest infectious disease. Now it ranks second, having claimed 1.3 million lives in 2022. While TB is less a problem in this country than other parts of the world, public health officials remain vigilant. The Centers for Disease Control and Prevention (CDC) reports that in 2022, TB incidence rates in this country were up 5.5% since 2021.

TB is a highly contagious disease caused by the bacterium Mycobacterium tuberculosis. It typically affects the lungs and is generally passed from person to person via airborne droplets—the kind that can spew when someone coughs, sneezes or speaks.

Public health laboratories play instrumental roles in fighting TB by identifying Mycobacterium tuberculosis and assessing the organism’s susceptibility to relevant drugs with the use and application of novel technologies. One of those technologies is next generation sequencing (NGS), which looks at the sequence of DNA present in a specimen to identify an organism and determine whether genetic mutations that may impact drug resistance are present. 

The Role of NGS in TB Detection

Key to curbing TB outbreaks is rapid detection and characterization of drug resistance. But that can be a challenge.

Mycobacterium tuberculosis is a slow-growing organism. Traditional methods used for detection and drug susceptibility testing depend on growth, but it can take weeks for a cultured sample to grow the bacterium. During that time, a patient may not be diagnosed or treated with appropriate drugs. That may be time that a patient isn’t limiting exposure to others, allowing infections to take root in communities.

But NGS may help slow the spread.

While NGS has been around for a while, [SB1] using it to gather clinical information is a relatively new application. NGS can not only identify the bacterium causing the disease, but it can also predict whether the bacterium isolated is resistant or susceptible to one of the anti-bacterial drugs used to treat TB. And it can do it all in a matter of days-to-weeks instead of the weeks-to-months it takes to grow a lab culture. That kind of timely, detailed diagnosis is essential not only in reducing community spread but also in eliminating the need for a patient to potentially utilize multiple costly and time-consuming treatment regimens before landing on the one that works.

More Treatment Options

Tuberculosis treatment can lasts months—sometimes as long as six-to-nine. And if the TB is drug resistant, treatment could linger on for up to two years. These long-in-duration treatment plans can be inconvenient for patients, making them more likely to abandon the drugs before they’ve taken full effect.

In 2022, CDC recommended the use of a multi-drug regimen called RPT-MOX for patients older than 12 with drug-susceptible pulmonary TB. Based on the results of an international clinical trial, researchers found that the four-month regimen was as effective in curing TB as the standard six-month method that had been one of the mainstays of treatment.

Another drug combination making news is BPaL, which in 2019 was US Food and Drug Administration (FDA) approved for use in people with drug-resistant TB as well as in people who can’t tolerate standard treatments or show no improvement when using them.

BPaL appears highly effective in treating TB. In one study, 95 of 107 people saw improvement in six months of treatment and six months of post-treatment follow-up. Only slightly more than 1.3% of TB cases in this country are multi-drug resistant, but worldwide the number reaches 20%, says WHO.

APHL and TB Testing

In 2015, APHL, in collaboration with CDC, established a National PHL Drug Susceptibility (DST) Reference Center for Mycobacterium tuberculosis to provide quality-assured drug susceptibility testing for eligible US public health laboratories. In 2024, the reference center began utilizing NGS clinically to predict for resistance to standard first-line drugs as well as drugs used in the RPT-MOX and BPaL testing regimens.  The reference center acts as an extension of CDC’s Division of TB Elimination Laboratory Branch and provides drug-susceptibility testing for US public health laboratories with low volumes of testing (fewer than 50 isolates annually). Participation in the reference center is voluntary. CDC’s testing services remain available to all US TB programs.

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