Jing Li,1,2,* Yinggai Song,3,* Xiao Liu,1,2 Jing Pan1,2 

1Department of Dermatology, Beijing Jishuitan Hospital, Capital Medical University, Beijing, People’s Republic of China; 2Fourth Medical College of Peking University, Beijing, People’s Republic of China; 3Department of Dermatology and Venerology, Peking University First Hospital, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Jing Li, Department of Dermatology, Beijing Jishuitan Hospital, Capital Medical University, No. 31 Xinjiekou East Street, Xicheng District, Beijing, 100035, People’s Republic of China, Email sophiali79@126.com

Background: Mycobacterium marinum and Candida metapsilosis are rare pathogens that cause chronic cutaneous and soft tissue infections. Although molecular technologies have improved their diagnosis, both diseases are challenging to treat. Here, we describe the first case of cutaneous granuloma caused by concurrent M. marinum and C. metapsilosis infections.
Case Presentation: A 67-year-old male patient presented with a one-year history of painful erythematous nodules on his left ring finger after a fish stabbing. He was apparently immunocompetent and received no immunosuppressive treatment. Histopathological examination revealed infectious granuloma. Positive cultures for mycobacteria and fungi, along with molecular testing, confirmed the mixed infection with M. marinum and C. metapsilosis. Considering his old age and hepatitis B core antibody, we initiated treatment with oral clarithromycin, topical sulfadiazine silver cream (SSC), and topical nifuratel nystatin gel (NNG). Owing to adverse events, the course of clarithromycin was limited to ten days. Nonetheless, a three-month regimen of continuous topical SSC and NNG led to the complete recovery of his lesions without recurrence.
Conclusion: This is the first reported case of mixed infection with M. marinum and C. metapsilosis. The combination therapy with 10-day oral clarithromycin treatment and 3-month topical SSC and NNG successfully treated superficial infections caused by these two distinct pathogens. This case could offer a viable alternative for patients unable to endure prolonged systemic therapy. Further studies are required to verify its efficacy.

Keywords: Mycobacterium marinum, Candida metapsilosis, mixed infection, sulfadiazine silver, nystatin, clarithromycin