Abstract:

Objective： To study the clinical and pathological characteristics of sporadic cutaneous infections due to nontuberculous mycobacteria (NTM), and investigate the diagnostic criteria and therapeutic principal. Methods: Totally 37 cases of sporadic cutaneous infections due to NTM were confirmed in the Department of Dermatology, Peking University People’s Hospital from January 2000 to March 2014. The microbiologic and clinical data were reviewed, and their skin biopsy specimens were reassessed. Results: Of all the 37 patients, 30 cases were Mycobacterium marinum infection, 6 were Mycobacterium abscessus infection, and one was Mycobacterium chelonea and Mycobacterium fortuitum infection. Identification of mycobacterial species by analysis of hsp65 gene in tissue DNA was more sensitive than traditional bacterial culture. The most common risk factors were traumatic injuries (21 of 37) and aquarium or fish-related job (21 of 37). One case of Mycobacterium abscessus infection occurred after autologous fat filling. Nodule and plaque were most common lesions in Mycobacterium marinum infection. Twenty-four of the 30 cases of Mycobacterium marinum infection presented with multiple lesions or sporotrichoid spread lesions. Ulceration, papules, abscess, and purulent discharge were observed in cases of Mycobacterium abscessus infection. Infective granuloma was most common histopathological appearance. For the treatment of Mycobacterium marinum infection, rifampin, ethambutol, and clarithromycin were commonly used (combination of two antibiotics, or three antibiotics), with the cure rate 90.00%. Four of the six Mycobacterium abscessus infections cases were cured, and one patient died. Conclusion: The most common species of sporadic cutaneous infections due to NTM is Mycobacterium marinum. Traumatic injuries, aquarium or fish-related job, and cosmetic surgeries are common risk factors. Mycobacterium marinum infection often presents with nodules, plaques, and sometimes sporotrichoid spread lesions. Lesions of Mycobacterium abscessus infection may vary. Pathological changes were not species specific, final diagnosis must be made depending on the identification of the microorganism. For the treatment of Mycobacterium marinum infection, excellent outcomes can be achieved by the combination of rifampin and ethambutol, and the combination of clarithromycin and rifampin or ethambutoland. Treatment regimens of Mycobacte-rium abscessus infection should be decided according to the results of antibiotic susceptibility testing.

Key words: Nontuberculous mycobacteria, Skin diseases, Bacterial infections, Pathology, Treatment outcome