<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Interferon gamma releasing assays (IGRAs) are extensively used in the diagnosis of latent tuberculosis infections. Comparing to tuberculin skin test (TST) they lack false positive results in the populations vaccinated with BCG, and in most non-tuberculous mycobacteria (NTM) infections. Nevertheless, <italic>Mycobacterium kansasii, Mycobacterium marinum</italic>, and <italic>Mycobacterium szulgai</italic> may induce positive IGRAs due to RD1 homology with <italic>Mycobacterium tuberculosis.</italic> The aim of the study was to investigate the possible influence of NTM respiratory isolates on the results of IGRAs. 39 patients (23 females and 16 males) of median age 61 years, with negative medical history concerning tuberculosis, entered the study. Identification of NTM was performed using the niacin test and molecular method GenoType CM test (Hain Lifescience). QFT-Plus was performed in 17 patients, T-SPOT-Tb – in 23 patients. Chest X-rays and a high-resolution computed tomography of the chest have been reviewed by the experienced radiologist blinded to the results of IGRAs, in search of past tuberculosis signs. Positive IGRAs results were obtained in three out of 39 patients (8%): 22% of patients with <italic>M. kansasii</italic> isolates and 18% of patients with radiological signs on HRCT that might be suggestive of past tuberculosis. Positive IGRAs correlated with radiological signs suggestive of past tuberculosis (r = 0.32, <italic>p</italic> = 0.04), and on the borderline with isolation of <italic>M. kansasii</italic> (r = 0.29, <italic>p</italic> = 0.06). These findings may suggest that a positive IGRAs result, in our material, could depend mostly on asymptomatic past Tb infection. The cross-reactivity of <italic>M. kansasii</italic> isolates with IGRAs was less probable; nevertheless, it requires further investigations.</p></abstract>

Interferon gamma releasing assays (IGRAs) are extensively used in the diagnosis of latent tuberculosis infections. Comparing to tuberculin skin test (TST) they lack false positive results in the populations vaccinated with BCG, and in most non-tuberculous mycobacteria (NTM) infections. Nevertheless, Mycobacterium kansasii, Mycobacterium marinum, and Mycobacterium szulgai may induce positive IGRAs due to RD1 homology with Mycobacterium tuberculosis. The aim of the study was to investigate the possible influence of NTM respiratory isolates on the results of IGRAs. 39 patients (23 females and 16 males) of median age 61 years, with negative medical history concerning tuberculosis, entered the study. Identification of NTM was performed using the niacin test and molecular method GenoType CM test (Hain Lifescience). QFT-Plus was performed in 17 patients, T-SPOT-Tb – in 23 patients. Chest X-rays and a high-resolution computed tomography of the chest have been reviewed by the experienced radiologist blinded to the results of IGRAs, in search of past tuberculosis signs. Positive IGRAs results were obtained in three out of 39 patients (8%): 22% of patients with M. kansasii isolates and 18% of patients with radiological signs on HRCT that might be suggestive of past tuberculosis. Positive IGRAs correlated with radiological signs suggestive of past tuberculosis (r = 0.32, p = 0.04), and on the borderline with isolation of M. kansasii (r = 0.29, p = 0.06). These findings may suggest that a positive IGRAs result, in our material, could depend mostly on asymptomatic past Tb infection. The cross-reactivity of M. kansasii isolates with IGRAs was less probable; nevertheless, it requires further investigations.

Interferon Gamma Release Assays in Patients with Respiratory Isolates of Non-Tuberculous Mycobacteria – a Preliminary Study

Polish Journal of Microbiology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Interferon gamma releasing assays (IGRAs) are extensively used in the diagnosis of latent tuberculosis infections. Comparing to tuberculin skin test (TST) they...

Age (years)	25–44	45–59	≥ 60	Total
IGRAs (+)	0	0	3 (14%)	3
IGRAs (−)	11	8	17	36
Total	11	8	20	39

Species	IGRA (+)	IGRA (−)	Total
M. kansasii	2 (22%)	7	9
M. avium	0	7	7
M. gordonae	0	6	6
M. chimaera	0	5	5
M. xenopi	0	5	5
M. fortuitum	1 (33%)	2	3
M. szulgai	0	1	1
M. abscessus	0	1	1
M. mucogenicum	0	1	1
M. smegmatis	0	1	1
Total	3 (8%)	36	39

Chest CT	IGRA (+)	IGRA (−)	Total
Past tb signs	3 (18%)	14 (82%)	17
No past tb signs	0 (0%)	22	22
Total	3	36	39

Sex	No of pts	Age Median (range)	BMI Median (range)	Number of patients with certain coexisting disease
Sex	No of pts	Age Median (range)	BMI Median (range)	COPD	ILD or GPA	CTD	CF	Npl	Others^*
Males	16	58.5 (28–75)	24.9 (19.5–38.9)	5	3	0	0	3	5
Females	23	62 (29–85)	23.8 (16.2–37.3)	5	6	4	2	2	4
Total	39	61 (27–85)	24.3 (15–38.9)	10	9	4	2	5	9

Interferon Gamma Release Assays in Patients with Respiratory Isolates of Non-Tuberculous Mycobacteria – a Preliminary Study

Article Category: original-paper

Pubblicato online: 27 mar 2019

Pagine: 15 - 19

DOI: https://doi.org/10.21307/pjm-2019-002

Parole chiave
interferon gamma release, non-tuberculous mycobacteria, latent tuberculosis infection

© 2019 Ewa Augustynowicz-Kopeć et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

IGRAs result according to patients’ age.

IGRAs results according to the NTM species.

The IGRAs results according to radiologic signs of past tuberculosis.

Characteristics of the population of patients, from whom NTM was isolated from respiratory specimens.

Interferon Gamma Release Assays in Patients with Respiratory Isolates of Non-Tuberculous Mycobacteria – a Preliminary Study

Article Category: original-paper

Pubblicato online: 27 mar 2019

Pagine: 15 - 19

DOI: https://doi.org/10.21307/pjm-2019-002

Parole chiaveinterferon gamma release, non-tuberculous mycobacteria, latent tuberculosis infection

© 2019 Ewa Augustynowicz-Kopeć et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

IGRAs result according to patients’ age.

IGRAs results according to the NTM species.

The IGRAs results according to radiologic signs of past tuberculosis.

Characteristics of the population of patients, from whom NTM was isolated from respiratory specimens.

Parole chiave
interferon gamma release, non-tuberculous mycobacteria, latent tuberculosis infection