Murine infection by Mycobacterium marinum is a reliable model for Bone and Soft-Tissue Damage

Extra-pulmonary tuberculosis (EPTB) constitutes 15-20% of the entire TB cases worldwide, and immune-suppressive conditions like HIV-AIDS further aggravate the disease often without symptoms and lack of proper diagnostic method delays the treatment. A thorough understanding of the EPTB infection and the pathogenesis is necessary and requires a reliable in-vivo animal model that mimics pathology similar to human infection. The M. marinum mice infection model presented here offers visible and quantifiable pathological features. Moreover, sections of the infected tails exhibited infiltration of the immune cells, a prominent feature frequently observed. Interestingly, the micro-CT imaging of the infected mices tails displayed bone erosion to the extent of the coccygeal vertebral loss. Furthermore, infection of the mice with drug-resistant such as Isoniazid (IRP) and Ethambutol (EmbRP) of M. marinum populations exhibited pathological features akin to wild-type M. marinum infection. At the same time, for EmbRP, the severity is significantly reduced, suggesting the nature of the selected population and its ability to retain or fix the virulent determinant(s) during bacterial growth. These findings advocate the use of the developed model to understand the EPTB precisely bone and spine TB, and it can be further utilized to develop novel therapeutics and diagnostics.