Mycobacterium Marinum Infection of the Skin Clinical Presentation

Updated: Mar 24, 2022
  • Author: Kirstin Altman, MD; Chief Editor: Dirk M Elston, MD  more...
  • Print


Patients at risk include anglers (commercial, recreational), oyster workers, swimmers, aquarium workers, and individuals with aquariums in their homes. Infection has also been reported following natural disasters involving the ocean. [16] In March 2014, the New York City Health Department reported an outbreak of roughly 30 cases secondary to seafood markets with live and raw fish in Chinatown. A single study found that 49% of M marinum infections were aquarium-related, 27% were associated with fish or shellfish injuries, and 9% were associated with injuries related to saltwater or brackish water. [1]

There are also documented reports of M marinum transmission via "fish manicures" or pedicures. In this practice, a client visits a spa and submerges their hands or feet into water containing live Garra rufa, doctor fish. The fish strip away the dead skin on the extremities, providing a form of exfoliation. [17]  Due to infection risk, these spa services are banned by law in several US states, as well as parts of Canada and Europe.

Patients may present with a papule, nodule, or ulcer at the site of trauma and a history of exposure to nonchlorinated water 2-3 weeks earlier. Patients may give a history of a papule or nodule that subsequently ulcerated and/or (1) spread up the finger or hand or (2) spread to involve a local joint or tendon. Over a period of months, localized cutaneous disease can spread to soft tissues. 

There is often a several-month delay between the onset of the lesions and the patient seeking medical care because the lesions are subacute or chronic and can be painless, although localized pain and induration are common. [10] Fever, lymphadenopathy, and systemic infection are rare, with the exception of in immunosuppressed patients. A thorough environmental exposure history should be conducted with consideration of infectious etiologies in patients with chronic skin conditions. [2]


Physical Examination

An erythematous or bluish 0.5- to 3-cm papule or nodule develops at the inoculation site. Ulceration can occur later, and subsequent lesions may be present along the path of lymphatic drainage of the extremity. This occurs in 25-50% of patients and is termed sporotrichotic spread.

The upper extremity is the inoculation site in 90% of cases, although infection of other body areas, including the face, has been reported. [18] M marinum infections of the hands often present as nodular lesions which can be mistaken for rheumatoid nodules. [19, 20] Systemic dissemination is exceptional and has been reported to occur only in immunocompromised patients (eg, solid-organ and hematopoietic stem cell transplant recipients, patients on anti-tumor necrosis factor (TNF) treatment. [10] )

Lymphadenopathy may be present.

Patients may have deeper involvement, with tenosynovitis, bursitis, septic arthritis, and osteomyelitis of the underlying bone. Dissemination to the bone marrow and abdominal viscera is rare.

If diagnosis is delayed, the infections can mimic rheumatoid arthritis, gout, trauma-related tenosynovitis, foreign body, deep fungal infections, or malignancy.



The cause is infection with M marinum. Exposure of traumatized skin to affected aqueous environments (such as fish tanks) is the leading predisposing factor. Other animal exposures such as a reptile vivarium or seafood market may more rarely result in acquisition of the infection. [21] Individuals who are consistently exposed to the organism are more likely to develop the infection. Hosts who are immunocompromised are also at increased risk.