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Use of a Single Xpert MTB/RIF Assay to Determine the Duration of Airborne Isolation in Hospitalized Patients With Suspected Pulmonary Tuberculosis

  • Husain Poonawala (a1), Surbhi Leekha (a2), Sandra Medina-Moreno (a3), Mala Filippell (a4), J. Kristie Johnson (a5), Robert R. Redfield (a1) (a3) and Kapil K. Saharia (a1) (a3)...



Hospitalized patients with suspected tuberculosis (TB) are placed in airborne isolation until 3 sputum smear samples are negative for acid-fast bacilli (AFB). The Xpert MTB/RIF assay (“Xpert”) nucleic acid amplification test (NAAT) to identify Mycobacterium tuberculosis DNA and resistance to rifampicin is superior to AFB sputum smear microscopy for the diagnosis of TB.


To compare the performance of a single Xpert to AFB smear microscopy for time to airborne infection isolation (AII) discontinuation.


Consecutive patients over 17 years of age in AII for suspected pulmonary TB between October 1, 2014, and March 31, 2016, with leftover respiratory AFB samples were enrolled in this study. A single Xpert was performed on the first available sample. Demographic, clinical, and microbiological data were recorded for each patient. We compared the duration of AII using a single Xpert to AFB smear microscopy under multiple theoretical scenarios using Kaplan-Meier cumulative incidence curves and the log-rank test.


In total, 131 samples were included in our performance analysis of the Xpert, and 114 samples were included in our AII analysis. Overall, 81 patients (65%) were immunosuppressed, of whom 46 (37%) were positive for human immunodeficiency virus (HIV). The sensitivity and specificity of Xpert for diagnosis of M. tuberculosis infection were 67% and 100%, respectively. Xpert was negative in all cases of nontuberculous mycobacteria. Use of a single Xpert reduced AII duration from a median of 67 hours per patient to 42 hours with usual reporting, to 26 hours with direct communication, and to 12 hours with immediate testing.


A single negative Xpert result can reduce AII duration compared to the AFB smear microscopy technique under multiple theoretical scenarios.

Infect Control Hosp Epidemiol 2018;39:590–595


Corresponding author

Address correspondence to Husain Poonawala, No. 1 Sathyamoorthy Road, Chetpet, Chennai 600031, India, (


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PREVIOUS PRESENTATION. The results of this study were presented at the Infectious Diseases Society of America Meeting 2016, on October 27, 2016, in New Orleans, Louisiana (abstract 544).



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1. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep 2005;54(RR-17):1141.
2. Jorgensen, JH, Pfaller, MA, Carroll, KC, et al. Manual of Clinical Microbiology, 11th ed. Washington, DC: American Society of Microbiology; 2015.
3. Behr, MA, Warren, SA, Salamon, H, et al. Transmission of Mycobacterium tuberculosis from patients smear-negative for acid-fast bacilli. Lancet 1999;353:444449.
4. Hernandez-Garduno, E, Cook, V, Kunimoto, D, Elwood, RK, Black, WA, FitzGerald, JM. Transmission of tuberculosis from smear negative patients: a molecular epidemiology study. Thorax 2004;59:286290.
5. Tostmann, A, Kik, SV, Kalisvaart, NA, et al. Tuberculosis transmission by patients with smear-negative pulmonary tuberculosis in a large cohort in the Netherlands. Clin Infect Dis 2008;47:11351142.
6. Abad, C, Fearday, A, Safdar, N. Adverse effects of isolation in hospitalised patients: a systematic review. J Hosp Infect 2010;76:97102.
7. Thomas, BS, Bello, EF, Seto, TB. Prevalence and predictors of compliance with discontinuation of airborne isolation in patients with suspected pulmonary tuberculosis. Infect Control Hosp Epidemiol 2013;34:967972.
8. Hughes, R, Wonderling, D, Li, B, Higgins, B. The cost effectiveness of nucleic acid amplification techniques for the diagnosis of tuberculosis. Respir Med 2012;106:300307.
9. Marks, SM, Cronin, W, Venkatappa, T, et al. The health-system benefits and cost-effectiveness of using Mycobacterium tuberculosis direct nucleic acid amplification testing to diagnose tuberculosis disease in the United States. Clin Infect Dis 2013;57:532542.
10. 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:e79669.
11. Boehme, CC, Nabeta, P, Hillemann, D, et al. Rapid molecular detection of tuberculosis and rifampin resistance. N Engl J Med 2010;363:10051015.
12. Steingart, KR, Sohn, H, Schiller, I, et al. Xpert(R) MTB/RIF assay for pulmonary tuberculosis and rifampicin resistance in adults. Cochrane Database Syst Rev 2013;1(1):CD009593.
13. Division of Microbiology Devices, Office of In Vitro Diagnostics and Radiological Health, Center for Devices and Radiological Health, Food and Drug Administration. Revised device labeling for the Cepheid Xpert MTB/RIF assay for detecting Mycobacterium tuberculosis . MMWR Morb Mortal Wkly Rep 2015;64:193.
14. Cowan, JF, Chandler, AS, Kracen, E, et al. Clinical impact and cost-effectiveness of Xpert MTB/RIF testing in hospitalized patients with presumptive pulmonary tuberculosis in the United States. Clin Infect Dis 2017;64:482489.
15. Chaisson, LH, Roemer, M, Cantu, D, et al. Impact of GeneXpert MTB/RIF assay on triage of respiratory isolation rooms for inpatients with presumed tuberculosis: a hypothetical trial. Clin Infect Dis 2014;59:13531360.
16. Lippincott, CK, Miller, MB, Popowitch, EB, Hanrahan, CF, Van Rie, A. Xpert MTB/RIF assay shortens airborne isolation for hospitalized patients with presumptive tuberculosis in the United States. Clin Infect Dis 2014;59:186192.
17. 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;62:10811088.
18. Adjemian, J, Olivier, KN, Seitz, AE, Holland, SM, Prevots, DR. Prevalence of nontuberculous mycobacterial lung disease in US Medicare beneficiaries. Am J Respir Crit Care Med 2012;185:881886.
19. Banerjee, R, Teng, CB, Cunningham, SA, et al. Randomized trial of rapid multiplex polymerase chain reaction-based blood culture identification and susceptibility testing. Clin Infect Dis 2015;61:10711080.
20. Choi, HW, Miele, K, Dowdy, D, Shah, M. Cost-effectiveness of Xpert(R) MTB/RIF for diagnosing pulmonary tuberculosis in the United States. Int J Tuberc Lung Dis 2013;17:13281335.


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