Abstract

CHIRA-ROMERO, F; ARAUJO-SILVA, C  and  SALINAS-CEVALLOS, J. Mycobacterium marinum: a case report. Rev. argent. dermatol. [online]. 2018, vol.99, n.1, pp.1-10. ISSN 1851-300X.

Introduction: Mycobacterium marinum is a type of non-tuberculous mycobacterium (NTM). Infection by this bacterium is frequent in freshwater or saltwater fish and very rarely causes infection in human population. Case report: we present the case of a 60-year-old male patient, who consulted for an ulcerative plaque on the back of his left hand. The histopathological study of biopsy reports: epithelial hyperplasia with a dense infiltrate in dermis and few granulomas with giant cells. Different tests were requested, PCR the only one positive for Mycobacterium marinum, which is why we proceeded to establish an antimicrobial regimen with favorable evolution. Discussion: infection by this bacterium is produced by direct inoculation of the microorganism through wounds or skin erosions or by contaminated fish bites. The forms of clinical presentation vary, being the most common the presence of solitary papules or nodules on fingers or hands. It can also manifest in the form of proximal or sporotrichoid lymphangitis, extension to deep organs, and facial sporotrichoid pattern. Diagnosis requires high index of suspicion, since the frequency of this condition is very low, from 0.04 to 0.27 per 100.000 habitants. Tissue biopsy provides the diagnosis in only half of the cases. Culture confirms the diagnosis, but they are reported as positive in 70 to 80% of cases. Nucleic acid amplification techniques, such as polymerase chain reaction (PCR) are other methods for diagnosis; its greatest advantage is the speed of its results compared to culture. There are many therapeutic modalities: topical treatment, systemic administration of antimicrobials, surgery, local thermotherapy and combination therapy. However, patients infected with M. marinum are usually treated with antimicrobials alone or in combination.

Keywords : Micobacterium marinum; non-tuberculous mycobacterium; atypical mycobacteria; treatment; antibiotics.