Mycobacterium fortuitum: Diagnostic and treatment challenges of skin disease in an immunocompetent host.
- 1Galway University Hospital, Galway, Republic of Ireland.
- 2University of Edinburgh, Edinburgh, Scotland, UK.
- 3University of Galway, Galway, Republic of Ireland.
Abstract
Mycobacterium fortuitum, a rapidly growing non-tuberculous mycobacterium (NTM), uncommonly causes skin and soft tissue disease. Immunocompetent patients often present with isolated lesions, whereas disseminated disease is often associated with an underlying immunocompromised state. A female in her thirties presented with a suspected lower leg insect bite that rapidly evolved into multiple subcutaneous nodules and consequential abscesses requiring surgical drainage. Initial cultures isolated various bacteria, including Carbapenemase-producing Enterobacterales (CPE), for which she received extended courses of antibiotics. Abscesses, however, continued to recur along the lymphatic distribution, which prompted skin biopsies for re-investigation. Histology demonstrated pustular inflammation and micro-abscesses, and Mycobacterium fortuitum was repeatedly isolated from distinct samples. Based on these laboratory results and a clinical course of progressive lesions, despite multiple courses of antibiotics, M. fortuitum was deemed the most likely responsible organism. Based on susceptibility testing, she received intravenous amikacin with oral moxifloxacin and co-trimoxazole as induction therapy. Directed anti-mycobacterial therapy has resulted in significant clinical improvement. M. fortuitum is an atypical organism often considered an environmental contaminant posing diagnostic challenges when more common organisms are concomitantly detected. Diagnosis is based on histology, microbiological identification, and clinical course of persistent deep-seated skin abscesses that progress despite standard treatment. Disease beyond a single lesion should raise concerns of possible severe or disseminated disease and immunosuppression.
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BibTeX
@article{conradie2026mycobacterium,
title = {{Mycobacterium fortuitum: Diagnostic and treatment challenges of skin disease in an immunocompetent host.}},
author = {Maria Conradie and Clarice Egan and Siobhán O'Regan and Peter Conlon and Paul Reidy and David Gallagher and Eibhlin Higgins},
journal = {IDCases},
year = {2026},
month = oct,
doi = {10.1016/j.idcr.2026.e02821},
url = {https://europepmc.org/article/MED/42997018},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Mycobacterium fortuitum: Diagnostic and treatment challenges of skin disease in an immunocompetent host.
AU - Maria Conradie
AU - Clarice Egan
AU - Siobhán O'Regan
AU - Peter Conlon
AU - Paul Reidy
AU - David Gallagher
AU - Eibhlin Higgins
PY - 2026
DA - 2026/10/23
JO - IDCases
DO - 10.1016/j.idcr.2026.e02821
UR - https://europepmc.org/article/MED/42997018
AB - Mycobacterium fortuitum, a rapidly growing non-tuberculous mycobacterium (NTM), uncommonly causes skin and soft tissue disease. Immunocompetent patients often present with isolated lesions, whereas disseminated disease is often associated with an underlying immunocompromised state. A female in her thirties presented with a suspected lower leg insect bite that rapidly evolved into multiple subcutaneous nodules and consequential abscesses requiring surgical drainage. Initial cultures isolated various bacteria, including Carbapenemase-producing Enterobacterales (CPE), for which she received extended courses of antibiotics. Abscesses, however, continued to recur along the lymphatic distribution, which prompted skin biopsies for re-investigation. Histology demonstrated pustular inflammation and micro-abscesses, and Mycobacterium fortuitum was repeatedly isolated from distinct samples. Based on these laboratory results and a clinical course of progressive lesions, despite multiple courses of antibiotics, M. fortuitum was deemed the most likely responsible organism. Based on susceptibility testing, she received intravenous amikacin with oral moxifloxacin and co-trimoxazole as induction therapy. Directed anti-mycobacterial therapy has resulted in significant clinical improvement. M. fortuitum is an atypical organism often considered an environmental contaminant posing diagnostic challenges when more common organisms are concomitantly detected. Diagnosis is based on histology, microbiological identification, and clinical course of persistent deep-seated skin abscesses that progress despite standard treatment. Disease beyond a single lesion should raise concerns of possible severe or disseminated disease and immunosuppression.
SN - 2214-2509
ER -