Acta Dermato-Venereologica 99-10CompleteContent

CLINICAL REPORT 889 Skin and Soft Tissue Infections Caused by Mycobacterium chelonae: More Common Than Expected? Ugur USLU, Olga BÖHM, Franz HEPPT and Michael STICHERLING Department of Dermatology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Universitätsklinikum Erlangen, Erlangen, Germany Mycobacterium chelonae is a rapidly growing non- tuberculous mycobacterium, which causes infections of the human skin and soft tissue. Despite an increasing incidence of such infections, patients are often misdiag- nosed. We report here 5 patients with cutaneous and/ or soft tissue infection due to M. chelonae who were diagnosed and treated at our centre. Two of the 5 pa- tients were on immunosuppressive treatment. While clinical presentations differed in each patient, all had a long history of skin lesions. In addition to careful histo- ry-taking, tissue biopsies were obtained for mycobacte- rial culture and histopathological examination. Culture- directed antibiotic therapy was initiated, which resulted in a slow, but continuous, healing of the lesions. In summary, M. chelonae infections are still relatively rare, but should be considered in both immunocompro- mised and immunocompetent patients with prolonged skin lesions resistant to standard antibiotic treatment. For diagnosis, tissue analysis for mycobacterial culture and histopathological examination, and once diagno- sed, adequate antibiotic treatment, is needed. Key words: non-tuberculous mycobacteria; NTM; rapidly gro- wing mycobacterium; RGM; skin infection; soft tissue infection. Accepted May 29, 2019; E-published May 29, 2019 Acta Derm Venereol 2019; 99: 889–893. Corr: Ugur Uslu, Department of Dermatology, Friedrich-Alexander-Uni- versität Erlangen-Nürnberg (FAU), Universitätsklinikum Erlangen, Ulmen- weg 18, DE-91054 Erlangen, Germany. E-mail: ugur.uslu@uk-erlangen. de M ycobacterium chelonae is classified as a rapidly growing non-tuberculous mycobacterium (NTM) (1–3). While other mycobacteria may take several weeks to grow when subcultured in the laboratory, rapidly growing NTMs are usually characterized by growth within 7 days (1–3). In general, NTM are considered less pathogenic than slow-growing species (4). M. chelonae, in particular, was first isolated by Freidmann from a sea turtle (Greek: chelōnē) in 1903 and is commonly asso- ciated with human skin and soft-tissue infections, mainly of the extremities (1–3, 5, 6). M. chelonae shows optimal growth at 28–32°C and usually causes disseminated rather than localized skin infection (1–3, 5, 6). Infections with M. chelonae may affect immunocom- promised patients, e.g. HIV-positive and cancer patients, as well as patients on immunosuppressive or biologic therapy due to autoimmune disorders or after organ trans- plantation (7–10). M. chelonae is frequently found in the SIGNIFICANCE Patients can present with infections of the skin and soft tis- sues due to the pathogen Mycobacterium chelonae. Clinical presentation of this relatively rare infectious disease may differ from individual to individual. Despite an increasing incidence, affected patients are often misdiagnosed. Thus, in addition to careful history-taking, tissue biopsies for my- cobacterial culture and histopathological examination are needed to reach a correct diagnosis. Once diagnosed, cul- ture-directed antibiotic therapy is required. We report here 5 patients with cutaneous and/or soft-tissue infections due to M. chelonae, who were diagnosed and treated appro- priately at our centre. natural environment, e.g. in soil, natural or treated water (11–13), and in association with plants or fish (14). M. chelonae has also been found within free-living amoebae (15, 16). Reports of infections of immunocompetent pa- tients with M. chelonae have increased in recent decades, especially following medical surgical procedures (17, 18), mesotherapy (19), or cosmetic procedures, e.g. cosmetic face surgery, breast surgery, or liposuction (20–23). These postsurgical infections are thought to be due to insufficient sterilization of used surgical instruments (24, 25). In ad- dition, M. chelonae infections have been reported after visits to tattoo studios or nail salons, due to contaminated pre-mixed ink or water (26, 27). More severe and disse- minated cases of infection with M. chelonae, however, have been reported in immunocompromised rather than immunocompetent patients (7–10). These studies show that exposure to, and infections with, M. chelonae is possible in different areas of daily life, including nosocomial surroundings. Although an increase in incidence has been seen over recent years (1, 28), infections are often misdiagnosed, since clinical pre- sentations may vary in each patient. In addition, optimal therapy is not well-established to date, and calculated antibiotic therapy based on in vitro sensitivity testing is needed in each case. The use of standard antibiotics is generally not adequate and often results on a prolonga- tion of symptoms and/or complications. We report here 5 patients with a diagnosis of cutaneous and/or soft tissue infection due to the rapidly growing NTM, M. chelonae. In addition to a detailed description of these cases, a summary of the disease characteristics, diagnostic procedures, and adequate treatment regimens is given for this relatively rare disorder. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica. doi: 10.2340/00015555-3230 Acta Derm Venereol 2019; 99: 889–893

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