Cutaneous infection caused by Mycobacterium chelonae in an immunocompromised individual

A 55-year-old woman with type II diabetes, a former smoker, and a history of immunosuppression was treated with methotrexate for pyoderma gangrenosum between 2009 and 2013. During this period, the lesions exhibited intermittent improvement followed by worsening. In 2021, she was referred to the Tuberculosis Reference Clinic for a skin biopsy with positive bacilloscopy and a positive culture for rapidly growing mycobacteria. At that time, hyperchromic, hyperemic, and edematous macules and circular ulcers with purulent exudates that drained spontaneously were observed on her lower limbs (Figure 1). The identification tests confirmed the presence of Mycobacterium chelonae¹. The treatment lasted 18 months and initially included amikacin, clarithromycin, and moxifloxacin². Sensitivity testing showed resistance to moxifloxacin, which was replaced with clofazimine. In this moment, bacilloscopy and mycobacterial cultures were performed and the wounds tested negative for draining secretions. By the end of the treatment, the lesions were reduced, which were accompanied by hyperchromic macules, some of which had dry crusts (Figure 2).

FIGURE 1:
Numerous purplish hyperchromic macules, associated with hyperemia and edema, and disseminated ulcers on the left lower limb. Circular ulcers, with well-defined edges and a base filled with purulent exudate. 2021, at the time of diagnosis.

FIGURE 2:
Lower left limb showing the healing of previous lesions associated with hyperpigmented hyperchromic macules, some with dry crust formation. Anterior region of the lower right limb, showing a flat scar with well-defined smooth edges. 2023, eighteen months after treatment.

Nontuberculous mycobacteria are ubiquitous and can cause diverse conditions, from asymptomatic colonization to infections^2,3. Diseases caused by M. chelonae are often associated with invasive procedures⁴. In this case, the microorganism was considered opportunistic and favored by prior immunosuppression^1,3. Although it is an uncommon pathogen⁴, considering its possibility in the absence of a response to initial therapy is crucial. Careful attention to the differential diagnosis of atypical lesions and performing mycobacteriological tests for accurate and timely diagnosis and treatment are necessary^3,5.

ACKNOWLEDGMENTS

We thank Cláudio José Augusto, the Bacterial and Fungal Diseases Service of the Ezequiel Dias Foundation (FUNED), the Mycobacteria Research Laboratory of the Faculty of Medicine of the Federal University of Minas Gerais (UFMG), and the Medical and Statistical Archive Service of the Clinical Hospital of UFMG for their support in conducting this project.

REFERENCES:

• ¹ Fundação Ezequiel Dias (FUNED). Instituto Octávio Magalhães. Serviço de Doenças Bacterianas e Fúngicas - Laboratório de Micobacterioses. Recomendações para o diagnóstico e teste de sensibilidade para micobactérias não tuberculosas (MNT) no estado de Minas Gerais, 2020 [cited Oct 01 2025]. Avaliable from: Avaliable from: http://www.funed.mg.gov.br/wp-content/uploads/2020/10/RECOMENDACOES-DIAGNOSTICO-MICOBACTERIAS-MNT.pdf
  » http://www.funed.mg.gov.br/wp-content/uploads/2020/10/RECOMENDACOES-DIAGNOSTICO-MICOBACTERIAS-MNT.pdf
• ² Brasil. Ministério da Saúde (MS). Secretaria de Vigilância em Saúde. Departamento de Doenças de Condições Crônicas e Infecção de Transmissão Sexual. Recomendações para o diagnóstico e tratamento das doenças causadas por micobactérias não tuberculosas no Brasil. 1ª edição. Brasília - DF: MS; 2021 [cited Oct 01 2025]. Available from: Available from: https://www.gov.br/aids/pt-br/central-de-conteudo/publicacoes/2021/recomendacoes-para-o-diagnostico-e-tratamento-das-doencas-causadas-por-micobacterias-nao-tuberculosas-no-brasil/view
  » https://www.gov.br/aids/pt-br/central-de-conteudo/publicacoes/2021/recomendacoes-para-o-diagnostico-e-tratamento-das-doencas-causadas-por-micobacterias-nao-tuberculosas-no-brasil/view
• ³ Haworth CS, Banks J, Capstick T, Fisher AJ, Gorsuch T, Laurenson IF, et al. British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD). Thorax. 2017;72(Suppl 2):ii1-ii64 [cited Oct 01 2025]. Avaliable from: Avaliable from: https://thorax.bmj.com/content/72/Suppl_2/ii1.long
  » https://thorax.bmj.com/content/72/Suppl_2/ii1.long
• ⁴ Leymarie A, Thibon P, Bernigaud C, Daurel C, Ouedraogo E, et al. Mycobacterium chelonae cutaneous infections unrelated to invasive procedures: A multicentre retrospective case series. J Eur Acad Dermatol Venereol. 2025;39:e537-e540 [cited Oct 01 2025]. Avaliable from: https://doi.org/10.1111/jdv.20521
  » https://doi.org/10.1111/jdv.20521
• ⁵ Barboza GCS, Almeida IN, Santos LBD, Augusto CJ, Leal ÉA, Pádua CAM, et al. Nontuberculous mycobacteria in patients of a specialty hospital. Rev Inst Med Trop Sao Paulo. 2023;30;65:e42 [cited Oct 01 2025]. Avaliable from: https://doi.org/10.1590/S1678-9946202365042
  » https://doi.org/10.1590/S1678-9946202365042

Ethics:

Report from the Ethics Committee of the Federal University of Minas Gerais, approved under protocol number 6.682.998 (CAAE 76360223.6.0000.5149).

Financial Support:

None

✉

Lucas Benício dos Santos. E-mail: [e-mail]

Conflict of Interest:

The authors declare no conflicts of interest.

Associated Editor:

Manoel O. da Costa Rocha Orcid: https://orcid.org/0000-0002-4721-1767

Publication Dates

• Publication in this collection
  02 Mar 2026
• Date of issue
  2026

History

• Received
  13 Nov 2025
• Accepted
  19 Dec 2025