Development of a diagnostic test for infections caused by non-tuberculous mycobacteria
Non-tuberculous mycobacteria (NTM) are a group of over 200 ubiquitous environmental species. NTM are commonly considered as clinically less important than other bacteria from the Mycobacterium genus such as Mycobacterium tuberculosis complex species and Mycobacterium leprae and, therefore, less frequently reported to public health authorities. However, in many cases, NTM infections are associated with respiratory diseases, disseminated infections, especially in immunocompromised patients, and cervical lymphadenitis in children. In the past years, NTM infections have increased and not only due to improved diagnosis, recording, and typing, but also to rising incidence rates of diseases caused by NTM. The standard criteria used for diagnosis, is the one proposed in 2007 in the American Thoracic Society (ATS) guidelines which require clinical, microbiological, and radiological evidence of disease before the diagnosis can be confirmed. In the case of lymphadenitis, differential diagnosis between NTM and TB infections is challenging as they both cause similar clinical and radiological features and they are frequently histologically alike. In addition, the clinical relevance of NTM isolates in pulmonary samples is not fully understood and remains difficult to determine. Acknowledging these limitations, the aim of this project is to develop and validate an NTM-specific immunodiagnostic test to help in the clinical evaluation of NTM infections.
So far, we have obtained promising results using an NTM-specific Enzyme-Linked Immunospot Assay (EliSpot) for the detection of IFN-γ produced by stimulated T-cells and we are now working on the development and validation of the NTM-iSpot (GenID GmbH, Straßberg, Germany), an NTM-specific 2-color fluorescence EliSpot that enables the evaluation of the immune response to NTM-specific antigens through T-cell production of IFN-γ and IL-2.