Abstract
BackgroundThe QuantiFERON-TB-Gold Test (QFT) is more specific than the Mantoux skin-test to discriminate between Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacterial (NTM) infections. Here we study the performance of the QFT in patients with NTM disease.MethodsFrom 2005 to 2011, nationwide patient data on positive NTM cultures (n = 925) were combined with nationwide data on QFT results (n = 16,133), both retrieved from the International Reference Laboratory of Mycobacteriology, Denmark. A total of 112 patients with NTM infections had a QFT performed, 53 patients had definite NTM disease, 10 had possible disease and 49 had NTM colonization.ResultsQFT was positive in 8% (4/53) of patients with definite disease, 40% (4/10) with possible disease and 31% (15/49) with colonization. Positivity rate was lowest among patients with definite disease infected with NTM without the RD1 region 4% (2/50). None of the 15 children with MAC lymphadenitis had a positive QFT.ConclusionThis study is one of the largest assessing IGRAs in patients with NTM disease in a TB low-incidence setting. Our study showed that the QFT holds potential to discriminate between NTM and MTB infections. We found no positive IGRA test results among children with NTM not sharing the RD1-region of MTB resulting in a 100% specificity and we suggest that a QFT in a child presenting with cervical lymphadenitis may be helpful in distinguishing NTM from TB lymphadenitis.
Highlights
Non-tuberculous mycobacteria (NTM) are a ubiquitous group of mycobacteria found in the environment worldwide [1,2]
QuantiFERON-TB-Gold Test (QFT) performance and non tuberculous mycobacteria In total 925 patients had a positive non-tuberculous mycobacterial (NTM) culture, 16,133 persons had a QFT performed and 167 persons had both QFT and NTM results available (Figure 1). Of these 55 persons were excluded; 29 because they had the QFT performed $6 month before or $1 month after NTM culture(s) were performed, 11 had discordant QFT results, 11 were infected with both Mycobacterium tuberculosis (MTB) and NTM, and in 4 cases the mycobacteria could not be identified to the species level
We identified 9 studies assessing Interferon-gamma (IFN-c) release assays (IGRAs) tests in patients with pulmonary NTM disease defined by the American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA)
Summary
Non-tuberculous mycobacteria (NTM) are a ubiquitous group of mycobacteria found in the environment worldwide (soil, dust, animals, and tap water) [1,2]. To aid in the diagnosis and treatment of pulmonary NTM disease, the American Thoracic Society (ATS) and the Infectious Disease Society of America (IDSA) have issued a set of guidelines regarding pulmonary NTM disease that is useful in discriminating disease from colonization [9]. These guidelines are based on a combination of clinical, radiographic, and microbiologic criteria that must be met to make a diagnosis of NTM lung disease. We study the performance of the QFT in patients with NTM disease
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