Cutaneous non‐tuberculous mycobacterial infections: A retrospective study of 94 cases from Germany

Summary Background Cutaneous non‐tuberculous mycobacterial infections (NTM) remain a diagnostic and therapeutic challenge. The aim of this study was to characterize cutaneous NTM infections in Germany over a 24‐year‐period. Patients and Methods 73 patients with cutaneous NTM infections diagnosed at 17 different German University Hospitals from 2000–2011 and 21 patients treated at the Department of Dermatology of the University Hospital Cologne, from 2010–2024. Retrospective analysis of patient, demographic, clinical information, and data on different diagnostic workups and therapeutic approaches/responses. Results Together, 94 cases were analyzed (71% males, mean age 50, > 75% immunocompetent). Exposure to fish tanks was the dominant risk factor. Pathogen detection by nucleic acid amplification test and/or culture was successful in 76%. The most common pathogen was Mycobacterium (M.) marinum (> 65%), followed by M. abscessus/chelonae . Immunosuppression was associated with NTM other than M. marinum . Over 90% were treated with oral antibiotics, in more than 50% with a single antibiotic (mostly clarithromycin). The most common combination was clarithromycin plus rifampicin. The mean duration of therapy was more than 4 months. Complications, adverse events, and relapses were rare. Conclusions Our findings highlight that there is a need for standardized diagnostic procedures‐ and therapeutic recommendations for cutaneous NTM infections.