Molecular Identification of Extrapulmonary Vaccine Adverse Events after BCG in Paraffin-Embedded Specimens.

According to the World Health Organization (WHO), around 1 million children worldwide are diagnosed with tuberculosis each year. The Bacillus Calmette-Guérin (BCG) vaccine has been used around the world for over 100 years. The complications of the BCG vaccination can occur in about 0,06% of children and include local or systemic adverse reactions. Due to the close analogy between the vaccine strain and other species of the Mycobacterium tuberculosis complex (MTBC), molecular methods are recommended for differential diagnosis of Vaccine adverse events (VAE) after BCG. The ability to quickly and specifically identify BCG is important in view of different treatment regimens. The aim of the study was to assess the usefulness of genetic testing for Mycobacterium bovis BCG in the paraffin-embedded specimens' methods. We describe two cases of VAE in immune-compromised children presenting with osteoarticular changes that had been clinically suspected of tuberculosis and led to molecular identification through GeneXpert, GenoType MTBC, and Spoligotyping. Results: Mycobacterium bovis BCG was detected in osteoarticular changes embedded in paraffin block of two patients. Conclusion: Genetic tests using paraffin-embedded materials allow for quick identification and differential diagnosis of patients with Tuberculosis and VAE after BCG. This is an important issue, especially in cases where the tissue has only been submitted for histopathological examination without microbiological diagnostics for tuberculosis.

Mycobacterial Interspersed Repeat Unit-Variable Number Tandem Repeat Typing of Mycobacterium avium Strains Isolated from the Lymph Nodes of Free-Living Carnivorous Animals in Poland.

Non-tuberculous mycobacteria (NTM) are ubiquitous organisms, of which some, especially those of the Mycobacterium avium complex (MAC), may be opportunistic animal and human pathogens. Infection with NTM can interfere with tuberculosis (TB) diagnosis and induce zoonoses, especially in immunocompromised individuals. Diseases caused by NTM have become more readily recognized; however, they are likely still underestimated. In this study, we identified and genotyped Mycobacterium avium strains that were isolated during TB monitoring among free-living carnivorous animals from southeastern Poland. In 2011-2020, lymph node samples from 192 such animals were tested for mycobacteria. A total of 41 isolates of M. avium strains were detected with the use of IS901, IS900, IS1245, and mycobacterial interspersed repeat unit-variable number tandem repeat (MIRU-VNTR) identification. Thirty-three were identified as M. avium subsp. avium. These strains were derived from 1 beech marten (Martes foina), 1 common buzzard (Buteo buteo), 2 European badgers (Meles meles), 3 wolves (Canis lupus), and 26 red foxes (Vulpes vulpes). One strain isolated from a wolf was identified as M. avium subsp. hominissuis. The results show the widespread occurrence of MAC bacilli in the studied environment and additionally comprise new data on the molecular characteristics of M. avium subspecies carried by free-living southeastern Polish carnivores.

N-Acylated Ciprofloxacin Derivatives: Synthesis and In Vitro Biological Evaluation as Antibacterial and Anticancer Agents.

A novel series of N-acylated ciprofloxacin (CP) conjugates 1-21 were synthesized and screened as potential antimicrobial agents. Conjugates 1 and 2 were 1.25-10-fold more potent than CP toward all Staphylococci (minimal inhibitory concentration 0.05-0.4 µg/mL). Most of the chloro- (3-7), bromo- (8-11), and CF3-alkanoyl (14-16) derivatives expressed higher or comparable activity to CP against selected Gram-positive strains. A few CP analogues (5, 10, and 11) were also more effective toward the chosen clinical Gram-negative rods. Conjugates 5, 10, and 11 considerably influenced the phases of the bacterial growth cycle over 18 h. Additionally, compounds 2, 4-7, 9-12, and 21 exerted stronger tuberculostatic action against three Mycobacterium tuberculosis isolates than the first-line antitubercular drugs. Amides 1, 2, 5, 6, 10, and 11 targeted gyrase and topoisomerase IV at 2.7-10.0 µg/mL, which suggests a mechanism of antibacterial action related to CP. These findings were confirmed by molecular docking studies. In addition, compounds 3 and 15 showed high antiproliferative activities against prostate PC3 cells (IC50 2.02-4.8 µM), up to 6.5-2.75 stronger than cisplatin. They almost completely reduced the growth and proliferation rates in these cells, without a cytotoxic action against normal HaCaT cell lines. Furthermore, derivatives 3 and 21 induced apoptosis/necrosis in PC3 cells, probably by increasing the intracellular ROS amount, as well as they diminished the IL-6 level in tumor cells.

Portable Surface Plasmon Resonance Detector for COVID-19 Infection.

Methods based on nucleic acid detection are currently the most commonly used technique in COVID-19 diagnostics. Although generally considered adequate, these methods are characterised by quite a long time-to-result and the necessity to prepare the material taken from the examined person-RNA isolation. For this reason, new detection methods are being sought, especially those characterised by the high speed of the analysis process from the moment of sampling to the result. Currently, serological methods of detecting antibodies against the virus in the patient's blood plasma have attracted much attention. Although they are less precise in determining the current infection, such methods shorten the analysis time to several minutes, making it possible to consider them a promising method for screening tests in people with suspected infection. The described study investigated the feasibility of a surface plasmon resonance (SPR)-based detection system for on-site COVID-19 diagnostics. A simple-to-use portable device was proposed for the fast detection of anti-SARS-CoV-2 antibodies in human plasma. SARS-CoV-2-positive and -negative patient blood plasma samples were investigated and compared with the ELISA test. The receptor-binding domain (RBD) of spike protein from SARS-CoV-2 was selected as a binding molecule for the study. Then, the process of antibody detection using this peptide was examined under laboratory conditions on a commercially available SPR device. The portable device was prepared and tested on plasma samples from humans. The results were compared with those obtained in the same patients using the reference diagnostic method. The detection system is effective in the detection of anti-SARS-CoV-2 with the detection limit of 40 ng/mL. It was shown that it is a portable device that can correctly examine human plasma samples within a 10 min timeframe.

An overview of tuberculosis outbreaks reported in the years 2011-2020.

BACKGROUND: In many countries tuberculosis (TB) remains a highly prevalent disease and a major contributor to infectious disease mortality. The fight against TB requires surveillance of the population of strains circulating worldwide and the analysis of the prevalence of certain strains in populations. Nowadays, whole genome sequencing (WGS) allows for accurate tracking of TB transmission. Currently, there is a lack of a comprehensive summary of the characteristics of TB outbreaks. METHODS: We systematically analyzed studies reporting TB outbreaks worldwide, monitored through WGS of Mycobacterium tuberculosis. We 1) mapped the reported outbreaks from 2011- 2020, 2) estimated the average size of the outbreaks, 3) indicated genetic lineages causing the outbreaks, and 4) determined drug-resistance patterns of M. tuberculosis strains involved in the outbreaks. RESULTS: Most data originated from Europe, Asia, and North America. We found that TB outbreaks were reported throughout the globe, on all continents, and in countries with both high and low incidences. The detected outbreaks contained a median of five M. tuberculosis isolates. Most strains causing the outbreaks belonged to lineage four, more rarely to lineage two. Reported outbreak isolates were often drug resistant. CONCLUSIONS: We conclude that more WGS surveillance of M. tuberculosis outbreaks is needed. Globally standardized procedures might improve the control of M. tuberculosis infections.

Mycobacterial Infections in Invasive Turtle Species in Poland.

Over the last 30 years, the number of invasive turtle species living in the wild has significantly increased in Poland. This proliferation carries many threats, which mainly include the displacement of native species of animals from their natural habitats. Turtles can also be reservoirs for pathogens, including bacteria from the Mycobacterium genus. In order to confirm or rule out the presence of acid-fast mycobacteria in the population of invasive turtle species, samples from carapace, plastron, internal organs and mouth cavity swabs from 125 animals were tested. Twenty-eight mycobacterial strains were isolated in culture, which were classified as atypical following multiplex-PCR reactions. The GenoType Mycobacterium Common Mycobacteria (CM) test, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, PCR-restriction fragment length polymorphism (PRA)-hsp65 and DNA sequencing were used to identify the species of isolates. Of the 28 strains, 11 were identified as M. fortuitum, 10 as M. chelonae, 3 as M. avium ssp. avium, 2 as M. nonchromogenicum and 1 each of M. neoaurum and M. scrofulaceum. The results of the research will also strengthen the understanding that these animals can be vectors for pathogens when living in the wild.

Is Serological Monitoring a Fit-for-purpose Tool to Assess the Epidemiological Situation of Tuberculosis in the Sylvatic Species of European Bison (Bison Bonasus) in Poland?

Introduction: Bovine tuberculosis is one of the most dangerous zoonotic diseases. Despite the near-complete elimination of the disease from cattle breeding in Poland achieved in 2009, its re-emergence is now observed. Globally, the number of human cases is underestimated and the importance of free-living animals as reservoirs of tuberculosis is growing. As a species highly susceptible to Mycobacterium tuberculosis complex infection, the European bison (Bison bonasus) has a role in the transmission of the disease in Poland. The purpose of the investigation was to assess the epidemiological situation of tuberculosis in Polish European bison serologically. Material and Methods: A total of 460 serum samples were collected from 436 European bison from 15 out of 26 national populations between 2013 and 2020. An M. bovis ELISA was used, and its sensitivity and specificity were assessed with an eyelid tuberculin skin test (TST) and interferon gamma release assay (IGRA). Results: Mycobacterium bovis antibodies were detected in nine serum samples. The presence of antibodies was found in two animals from the Bialowieza Forest (1.2% of the population), and one each from the Borecka Forest (2.4%) and the Warsaw Zoo (14.3%). One European bison among the 14 sampled (7.1%) from Smardzewice was positive on five occasions. Other samples from Smardzewice and the Bieszczady Mountains, where tuberculosis had previously been reported, were negative. Conclusion: ELISA testing is an effective, easy and cost-efficient tool for monitoring of tuberculosis-naïve populations. Serological testing in tuberculosis control programmes can significantly improve the detection of infected herds. Antibody ELISAs may supplement TST and IGRA, but cannot replace them.

Mycobacterium bovis Transmission between Cattle and a Farmer in Central Poland.

INTRODUCTION: Zoonoses have recently become an increasing public health problem. Zoonoses are estimated to account for 60% of all emerging infectious diseases. One particularly important zoonosis is human tuberculosis, especially tuberculosis due to Mycobacterium bovis (M. bovis), which is naturally resistant to pyrazinamide (PZA). MATERIAL AND METHODS: The patient had a pulmonary form of tuberculosis accompanied by a cough and fever. At the same time, the disease was also confirmed in 20 out of 25 cattle on the farm. The clinical specimen (sputum) was examined in accordance with the European Union (EU) laboratories' methodology. Tissue materials from cattle were verified in the National Veterinary Research Institute (NVRI), in the Bovine tuberculosis (BTB) Reference Laboratory, Pulawy, Poland and tested in accordance with the guidelines for the laboratory diagnosis of BTB. RESULTS: All M. bovis isolates represented one spoligotype, SB0120. The results of mycobacterial interspersed repetitive unit variable number tandem repeat (MIRU-VNTR) evaluation showed the same genetic pattern. CONCLUSIONS: Findings from this study suggest the first confirmed interspecific transmission of Mycobacterium bovis, between a farmer and his cattle, in Poland. Present findings support the increasing concern regarding zoonotic TB that has been highlighted elsewhere.

Main-chain flexibility and hydrophobicity of ionenes strongly impact their antimicrobial activity: an extended study on drug resistance strains and Mycobacterium.

The spread of antibiotic-resistant pathogens and the resurgence of tuberculosis disease are major motivations to search for novel antimicrobial agents. Some promising candidates in this respect are cationic polymers, also known as synthetic mimics of antimicrobial peptides (SMAMPs), which act through the membrane-lytic mechanism. Development of resistance toward SMAMPs is less likely than toward currently employed antibiotics; however, further studies are needed to better understand their structure-activity relationship. The main objective of this work is to understand the cross-influence of hydrophobicity, main-chain flexibility, and the topology of ionenes (polycations containing a cationic moiety within the main-chain) on activity. To fulfill this goal, a library of ionenes was developed and compared with previously investigated molecules. The obtained compounds display promising activity against the model microorganisms and drug-resistance clinical isolates, including Mycobacterium tuberculosis. The killing efficiency was also investigated, and results confirm a strong effect of hydrophobicity, revealing higher activity for molecules possessing the flexible linker within the polymer main-chain.

Tuberculosis in Poland: Epidemiological and Molecular Analysis during the COVID-19 Pandemic.

The COVID-19 pandemic may have a negative impact on the proper implementation of TB control programmes and may increase TB incidence rates in the near future. The aim of this study was to perform an epidemiological and molecular analysis of Mycobacterium tuberculosis strains cultured from tuberculosis patients in Poland in 2020 and to compare the results of monitoring drug-resistant tuberculosis in Poland with previous studies in 2012 and 2016. The analysis was based on questionnaires and strains sent by regional laboratories during the 12 months of 2020. Molecular analysis was performed by spoligotyping 20% of the strains sensitive to the four primary antimycobacterial drugs and all of the drug-resistant strains. The number of strains sent for analysis dropped threefold, from 4136 in 2012 to 1383 in 2020. The incidence of tuberculosis among men was higher than among women. There was an increase in strains' resistance to antimycobacterial drugs in both newly diagnosed patients, from 4.4% in 2012 to 6.1% in 2020, and previously treated patients, from 11.7% to 12.3%. Four-year resistance increased to 1% and 2.1%, respectively. The spoligotype SIT1 was the most abundant among the resistant strains (17%), and SIT53 (13.9%) was the most common among susceptible strains.

New RAPMYCOI SensititreTM Antimicrobial Susceptibility Test for Atypical Rapidly Growing Mycobacteria (RGM).

Rapidly growing mycobacteria (RGM) cause an increasing international concern, mainly due to their natural resistance to many antibiotics. The aim of this study was to conduct species identification and determine the antimicrobial susceptibility profiles of RGM isolated in Poland. Antimicrobial susceptibility was tested using broth microdilution and the RAPMYCOI panel. A total of 60 strains were analysed, including the following species: M. fortuitum complex (30), M. abscessus subsp. abscessus (16), M. abscessus subsp. massiliense (7), M. chelonae (5), and M. mucogenicum (2). For 12 M. abscessus subsp. abscessus strains, the presence of the erm 41T28 genotype associated with inducible macrolide resistance and a functional erm gene was confirmed. A MUT2 mutation in the rrl gene (constitutive resistance) was identified for two strains from the subtype M. abscessus subsp. massiliense. Among the 15 tested antibiotics, amikacin and linezolid had the strongest antimycobacterial activity. Most of the tested strains were resistant to doxycycline and trimethoprim/sulfamethoxazole. Tigecycline MICs were low for all tested strains. Findings from our study highlight the importance of correct identification of clinical isolates and antimicrobial susceptibility testing.

The Effect of Conjugation of Ciprofloxacin and Moxifloxacin with Fatty Acids on Their Antibacterial and Anticancer Activity.

Novel conjugates (CP) of moxifloxacin (MXF) with fatty acids (1m-16m) were synthesized with good yields utilizing amides chemistry. They exhibit a more pronounced cytotoxic potential than the parent drug. They were the most effective for prostate cancer cells with an IC50 below 5 µM for respective conjugates with sorbic (2m), oleic (4m), 6-heptenoic (10m), linoleic (11m), caprylic (15m), and stearic (16m) acids. All derivatives were evaluated against a panel of standard and clinical bacterial strains, as well as towards mycobacteria. The highest activity towards standard isolates was observed for the acetic acid derivative 14m, followed by conjugates of unsaturated crotonic (1m) and sorbic (2m) acids. The activity of conjugates tested against an expanded panel of clinical coagulase-negative staphylococci showed that the compound (14m) was recognized as a leading structure with an MIC of 0.5 µg/mL denoted for all quinolone-susceptible isolates. In the group of CP derivatives, sorbic (2) and geranic (3) acid amides exhibited the highest bactericidal potential against clinical strains. The M. tuberculosis Spec. 210 strain was the most sensitive to sorbic (2m) conjugate and to conjugates with medium- and long-chain polyunsaturated acids. To establish the mechanism of antibacterial action, selected CP and MXF conjugates were examined in both topoisomerase IV decatenation assay and the DNA gyrase supercoiling assay, followed by suitable molecular docking studies.

Use of a FluoroType® System for the Rapid Detection of Patients with Multidrug-Resistant Tuberculosis-State of the Art Case Presentations.

According to the World Health Organization (WHO), there were 465,000 cases of tuberculosis caused by strains resistant to at least two first-line anti-tuberculosis drugs: rifampicin and isoniazid (MDR-TB). In light of the growing problem of drug resistance in Mycobacterium tuberculosis across laboratories worldwide, the rapid identification of drug-resistant strains of the Mycobacterium tuberculosis complex poses the greatest challenge. Progress in molecular biology and the development of nucleic acid amplification assays have paved the way for improvements to methods for the direct detection of Mycobacterium tuberculosis in specimens from patients. This paper presents two cases that illustrate the implementation of molecular tools in the recognition of drug-resistant tuberculosis.

From NTM (Nontuberculous mycobacterium) to Gordonia bronchialis-A Diagnostic Challenge in the COPD Patient.

In patients with chronic obstructive pulmonary disease, respiratory infections are of various aetiology, predominantly viral and bacterial. However, due to structural and immunological changes within the respiratory system, such patients are also prone to mycobacterial and other relatively rare infections. We present the 70-year old male patient with chronic obstructive pulmonary disease (COPD) and coexisting bronchial asthma, diagnosed due to cough with purulent sputum expectoration lasting over three months. The first microbiological investigation of the sputum sample revealed the growth of mycobacteria. The identification test based on protein MPT64 production indicated an organism belonging to NTM (nontuberculous mycobacterium). However, further species identification by genetic testing verified the obtained culture as not belonging to the Mycobacterium genus. Based on observed morphology, the new characterisation identified an aerobic actinomycete, possibly a Nocardia spp. The isolated strain was recultured on standard microbiological media. The growth of colonies was observed on Columbia blood agar plates and solid Löewenstein-Jensen medium. The Gram and Zhiel-Nielsen stains revealed the presence of Gram-positive acid-fast bacilli. The extraction protocol and identification were performed in two repetitions; the result was G. bronchialis, with a confidence value of 99% and 95%, respectively. The gene sequencing method was applied to confirm the species affiliation of this isolate. The resulting sequence was checked against the 16S ribosomal RNA sequences database (Bacteria and Archaea). The ten best results indicated the genus Gordonia (99.04-100%) and 100% similarity of the 16S sequenced region was demonstrated for Gordonia bronchialis. The case described indicates that the correct interpretation of microbiological test results requires the use of advanced microbiology diagnosis techniques, including molecular identification of gene sequences. From a clinical point of view, Gordonia bronchialis infection or colonization may present a mild course, with no febrile episodes and no significant patient status deterioration and thus, it may remain undiagnosed more often than expected.

Mycobacterium chimaera as an Underestimated Cause of NTM Lung Diseases in Patients Hospitalized in Pulmonary Wards.

Mycobacterium chimaera is the newly described species belonging to Mycobacterium avium complex (MAC), with morphology and growth characteristics closely related to Mycobacterium intracellulare. The aim of this retrospective study was to analyze the frequency and clinical significance of M. chimaera identification in the population of patients with previous positive respiratory cultures for M. intracellulare or MAC. 200 strains of M. intracellulare or MAC, isolated from respiratory specimens of patients hospitalized in pulmonary wards, between 2011 and 2020, were retrospectively analyzed with GenoType NTM-DR test. 88 (44%) of strains were re-classified to M. chimaera species. Analysis of clinical data in 30 patients with positive M. chimaera isolates revealed that they were diagnosed with chronic obstructive pulmonary disease (COPD) - 27%, past tuberculosis - 20%, or interstitial lung diseases - 17%, respectively. Non-tuberculous mycobacterial lung disease (NTMLD) caused by M. chimaera has been recognized in 53% of patients, most often in those presenting with post-tuberculous lung lesions. M. chimaera was almost exclusively isolated from respiratory specimens of patients with underlying lung diseases, especially those with COPD and/or past tuberculosis. NTMLD due to M. chimaera was diagnosed predominantly in patients with past tuberculosis.

Epidemiological characterization of Mycobacterium caprae strains isolated from wildlife in the Bieszczady Mountains, on the border of Southeast Poland.

BACKGROUND: The majority of animal tuberculosis (TB) cases reported in wildlife in Poland over the past 20 years have concerned the European bison inhabiting the Bieszczady Mountains in Southeast Poland: an area running along the border of Southeast Poland. As no TB cases have been reported in domestic animals in this region since 2005, any occurrence of TB in the free-living animals inhabiting this area might pose a real threat to local livestock and result in the loss of disease-free status. The aim of the study was to describe the occurrence of tuberculosis in the wildlife of the Bieszczady Mountains and determine the microbiological and molecular characteristics of any cultured strains. Lymph node samples were collected for analysis from 274 free-living animals, including European bison, red foxes, badgers, red deer, wild boar and roe deer between 2011 and 2017. Löwenstein-Jensen and Stonebrink media were used for culture. Molecular identification of strains was performed based on hsp65 sequence analysis, the GenoType®MTBC (Hain Lifescience, Germany) test, spoligotyping and MIRU-VNTR analysis. RESULTS: Mycobacterium caprae was isolated from the lymph nodes of 21 out of 55 wild boar (38.2%; CI 95%: 26.5%, 51.4%) and one roe deer. Since 2014, no new TB cases have been reported in the Bieszczady European bison population. CONCLUSIONS: The identification of TB in wild boar in the Bieszczady is an alarming phenomenon, which requires further investigation. The Bieszczady mountains are a precious, unique area, home to many protected species. However, it is also the only area in Poland where TB cases have been reported in free-living animals. The occurrence of TB in wild boar inhabiting this area might pose a real threat to local livestock and many of the protected species (for example European bison that can share feeding places with wild boar). Given this situation, ongoing monitoring of the prevalence of TB should be conducted, and protective measures should be considered.

Non-Tuberculous Mycobacteria in Respiratory Specimens of Patients with Obstructive Lung Diseases-Colonization or Disease?

Non-tuberculous mycobacteria (NTM) are increasingly a cause of human respiratory tract colonization and mycobacterial lung disease (NTM-LD), especially in patients with chronic lung diseases. The aim of the present study was to find the factors predictive of NTM-LD in patients with obstructive lung diseases and NTM respiratory isolates. A total of 839 isolates of NTM, obtained from 161 patients between 2010 and 2020 in a single pulmonary unit, have been retrospectively reviewed. Of these isolates, 73 concerned 36 patients with obstructive lung diseases (COPD-26, asthma-3, COPD/asthma overlap syndrome-7). NTM-LD was recognized according to the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) criteria in 17 patients, colonization in 19. Lower BMI, elevated body temperature on admission, infiltrative/cavitary lesions on chest CT, and NTM species other than Mycobacterium gordonae were the significant predictors of NTM-LD recognition. Based on the above-mentioned predictive factors, an original scoring system was implemented. The diagnostic utility of the scoring system was higher than that of single parameters. We conclude that NTM-LD prediction in patients with obstructive lung diseases and positive respiratory isolates is difficult. A scoring system based on clinical, radiological and microbiological characteristics was capable of facilitating the differential diagnosis, but it needs further validation in a larger study group.

Molecular methods in diagnostics of post-BCG vaccine adverse events.

INTRODUCTION: Bacillus Calmette-Guérin (BCG) is the only tuberculosis vaccine available and although it has been routinely used for more than 80 years, its protective effect varies depending on the age and the form of tuberculosis. Due to the close analogy between the vaccine strain and other species of the Mycobacterium tuberculosis complex, molecular methods are recommended for differential diagnosis of post-BCG complications. The aim of the study was to assess usefulness of molecular methods in diagnosis of post-BCG vaccine adverse events (VAEs). MATERIAL AND METHODS: M. tuberculosis complex strains obtained in 2011-2017 from 68 ill children were subjected to molecular analysis. RESULTS: Molecular analysis of 68 strains showed 100% agreement between the results in the GenoType MTBC method and the multiplex PCR method. For the strains isolated from 45 patients with suspected VAE, M. bovis BCG was obtained, whereas the strains isolated from the remaining 23 children were identified as M. tuberculosis. The analysis confirmed the close relationship between the result of identification and the type of material as well as the patient's age. CONCLUSIONS: The use of genetic methods enables quick and detailed diagnostics of infections caused by M. bovis BCG, which allows for the confirmation or exclusion of VAE.

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

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 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.