FDA permits marketing of TB bacteria and antibiotic-resistance test

The US Food and Drug Administration (FDA) has authorised the marketing of the Xpert MTB/RIF assay, manufactured by Cepheid. This is the first FDA-reviewed test that can rapidly detect the bacteria that cause tuberculosis (TB) and determine if the bacteria contain genetic markers that make them resistant to rifampin, an important antibiotic for the treatment of TB.

TB is caused by bacteria that belong to a group known as Mycobacterium tuberculosis complex (MTB-complex), which usually attacks the lungs. Not everyone infected with MTB develops active TB - in fact, around one-third of the world’s population is thought to have been infected - and only people with active TB can spread the bacteria to other people. Those with weakened immune systems are at a much higher risk for developing TB once infected with the bacteria, and the disease can be fatal if left untreated, especially for people with HIV.

“New tools, including rapid and accurate diagnostic tests, are critical to advance the fight against TB,” said Dr RADM Kenneth G Castro, director of CDC’s Division of Tuberculosis Elimination. “Early diagnosis and effective treatment for both drug-susceptible and drug-resistant cases are essential for improving patient health, preventing the spread of disease to others and, ultimately, achieving our goal of TB elimination in the US.”

Designed for use on Cepheid’s GeneXpert systems, the new test not only detects the presence of MTB-complex DNA but also mutations associated with resistance to rifampin, a critical first-line drug for treatment of the disease and a reliable surrogate marker of strains that may be multidrug-resistant (MDR-TB). The assay is less complex to perform than previous FDA-cleared tests, with results available in approximately 2 h as opposed to a traditional waiting time of 1-3 months.

Cepheid Chairman and CEO John Bishop said the swift detection of multidrug-resistant bacteria will allow clinicians to optimise patients’ drug therapy early in the course of the disease, as those with MDR-TB need more intensive and prolonged treatment. Dr Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological, further stated, “The early and rapid detection of rifampin-resistant TB can help curb the spread of drug-resistant TB.”

The symptoms of TB in its early stages - including coughing, chest pains and fatigue - are similar to many different types of infections, so it is important to have an accurate test to rule out the disease. Cepheid’s Chief Medical and Technology Officer, Dr David H Persing, said the test will “help to eliminate guesswork and deliver maximum medical value in the management of TB”.

He added, “Xpert MTB/RIF is the most technologically advanced test for TB ever developed, yet it is simple enough to be performed across multiple shifts in laboratories across the country.”