The US National Tuberculosis Controllers Association (NTCA) and the Association of Public Health Laboratories (APHL) have issued guidance on the use of the Xpert MTB/RIF test from Cepheid, Sunnyvale, Calif, to support decisionmaking on using airborne infection isolation, commonly referred to as respiratory isolation, in healthcare settings.
Cepheid’s Xpert MTB/RIF test received FDA clearance for expanded claims relating to respiratory isolation in February 2015, but this is the first formal set of recommendations by NTCA and APHL on using the Xpert MTB/RIF test. The cartridge-based nucleic acid amplification test is designed to identify Mycobacterium tuberculosis (MTB) and resistance to rifampicin (RIF).
Respiratory isolation can be costly and has also been shown to impede quality of care and patient satisfaction in some cases.1,2 Presently, many patients who are suspected of having active pulmonary MTB infections are placed in respiratory isolation until three respiratory specimens, each collected at least 8 hours apart, are shown to be negative for tuberculosis (TB) using acid-fast smear-microscopy.
In a recent study, a single Xpert MTB/RIF test was shown to have a negative predictive value of 99.7%. Administering a second Xpert test increased the overall negative predictive value to 100% when compared to acid-fast bacillus (AFB) smear microscopy, suggesting a role for the Xpert test in aiding clinical decisions regarding the use of respiratory isolation. In the same study, the Xpert MTB/RIF test identified all cases of TB confirmed by mycobacterial culture, the current gold standard for TB diagnosis, and identified the majority of cases with RIF resistance.3
“Our study showed that Xpert MTB/RIF can play an important role in the respiratory isolation algorithm, even in lower prevalence settings like the United States,” says Anne Luetkemeyer, MD, lead author of the NIAID study and associate professor of infectious disease at the University of California, San Francisco. “For healthcare settings where respiratory isolation is used, NTCA’s new recommendations can help shorten unnecessary and costly isolation treatment for TB-negative patients, allowing hospital and public health workers to target their infection control efforts on those who do have TB. Xpert MTB/RIF can also identify many patients who will be missed with initial negative AFB smears, allowing a more prompt tuberculosis diagnosis.”
“Respiratory isolation is costly from the hospital’s perspective and unpleasant from the patient’s point of view,” says David H. Persing, MD, PhD, chief medical and technology officer at Cepheid. “Many acute care hospitals in the United States spend millions of dollars each year on respiratory isolation of pulmonary TB suspects who eventually test negative for TB. The increased sensitivity of Xpert MTB/RIF over traditional acid-fast smears can assist healthcare facilities in keeping more patients who do have pulmonary TB in respiratory isolation, thereby preventing transmission, while releasing those who do not need to be there.”
“While Cepheid’s Xpert MTB/RIF test is recognized for its transformative role in TB management in the developing world, it is particularly gratifying to see the test recognized as a potentially valuable and cost-effective aid to managing patients suspected of having TB here in the United States,” says John Bishop, chairman and chief executive of Cepheid. “NTCA and APHL are to be applauded for this recommendation, which could allow many patients to be released from unnecessary isolation and taken off unnecessary antibiotic therapies substantially faster than under the previous protocol.”4
The Xpert MTB/RIF test is currently available in the United States and in countries accepting the CE mark. For more information, visit Cepheid.
- Catalano G, Houston SH, Catalano MC, et al. Anxiety and depression in hospitalized patients in resistant organism isolation. South Med J. 2003;96:141–146.
- Millman AJ, Dowdy DW, Miller CR, et al. Rapid molecular testing for TB to guide respiratory isolation in the US: a cost-benefit analysis. PLoS One. 2013;8(11):e79669-10.1371; doi: 10.1371/journal.pone.0079669.
- Luetkemeyer AF, Firnhaber C, Kendall MA, et al. Evaluation of Xpert MTB/RIF versus AFB smear and culture to identify pulmonary tuberculosis in patients with suspected tuberculosis from low- and higher prevalence settings. Clin Infect Dis. 2016;62(9):1081–1088; doi: 10.1093/cid/ciw035.
- Davis JL, Kawamura M, Chaisson LH, et al. Impact of GeneXpert MTB/RIF on patients and tuberculosis programs in a low-burden setting. Am J Resp Care Med. 2014;189:1551–1559; doi: 10.1164/rccm.201311-1974OC.