Abstract: Objective: To construct a stable and repeatable mouse model of local infection of Mycobacterium marinum (M. marinum) and simulate the pathophysiological characteristics of human skin and soft tissue infection. Methods: The strains were inoculated by subcutaneous/pad injection on the back of mice (with bacterial amounts of 10⁶CFU, 10⁴CFU, and 10²CFU respectively), and the local lesions, histopathology and immune responses of the infection were dynamically monitored according to different rearing environments (18℃ and 25℃). Results: The inflammation model of local M. marinum granuloma was successfully established in mice, and the severity of infection was dose-dependent. Low temperature promoted early formation of skin infection granuloma in low dose group. Compared with the foot pad group, the infection scope of the skin group was more limited, M. marinum was not easy to spread, and no infection was found in the internal organs. Conclusion: The mouse model of local infection established in this study has strong repeatability and clear pathological characteristics, which provides an important tool for the study of the pathogenic mechanism of M. marinum and the development of anti-mycobacterium drugs.

Key words: Mycobacterium marinum, mice, skin infection model, foot pad infection model