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Sunday, April 18th, 2004, 11:34 PM
A site for everyone interested in the hobby
of keeping and/or breeding tropical, marine, coldwater & pond fish.


Thursday, May 20th, 2004, 07:27 PM
Aquarium hobbyists and dabblers alike, be careful in sticking your hand and arm into an aquarium.
The water may contain a bacteria, Mycobacterium marinum, which may enter your body through a small wound.
It may produce kind of ulcers in your sinews and joints.
Please care to read this articles:

Mycobacterium Marinum
Medical Editor: Frederick Hecht, M.D.

What is Mycobacterium marinum?
How does a person get infected with it?
What are the symptoms?
How is this infection treated?
How can I protect myself from this infection?
What is Mycobacterium marinum?

Mycobacterium marinum (M. marinum) is a slowly growing bacteria that may cause disease in fish and people. The bacteria is normally found in bodies of fresh or salt water in many parts of the world. Skin infection with Mycobacterium marinum is relatively rare and is usually acquired from swimming pools, aquariums, or fish-handling. This bacteria does not grow at normal body temperature. That is why it remains localized to the cooler skin surface.

How does a person get infected with it?

Human infections with M. marinum under normal circumstances are rare. However, people who have breaks in the skin such as cuts and scrapes are at increase risk:

when in contact with water from an aquarium or fish tank
when handling, cleaning, or processing fish, or
while swimming or working in fresh or salt water.
One form of the infection, known as "swimming pool granuloma," can occur when there is inadequate chlorination of swimming pools. However, in the US, most human infections with this bacteria have been associated with contact with fish tanks .

M. marinum infection is not spread from person to person.

What are the symptoms?

When M. marinum infects the skin, it causes localized microscopic nodules to form. These nodules are called granulomas. They occur at sites of skin trauma where there are scratches, cuts, and the like.

The granulomas usually appear within 2-3 weeks of exposure. Some reported cases have developed 2 to 4 months or more after exposre to M. marinum because of the very slow-growing nature of this bacterium.

The most frequent sign is a slowly developing nodule (raised bump) at the site the bacteria entered the body. Frequently, the nodule is on the hand or upper arm. Later the nodule can become an enlarging sore (an ulcer). Swelling of nearby lymph nodes occurs. Multiple granulomas may form in a line along the lymphatic vessel that drains the site. These lesions will usually spontaneously heal in several months. This infection can also involve the joints (septic arthritis) and bones (osteomyelitis).

A health care provider should be consulted if a skin nodule or reddened sore (ulcer) develops following direct skin contact with fresh or salt water or after handling or processing fish.

For people with compromise of the immune system, M. marinum infection can be especially serious and involve disseminated (widespread) disease. If an infection is suspected under such circumstances, a health care provider should be promptly consulted.

How is this infection treated?

Anti-tuberculous drugs speed healing. These drugs usually need to be taken for 3-6 months. The preferred combination of drugs is Rifampin + Ethambutol. Depending on the antibiotic sensitivity of the organism, alternative drugs are Rifampin + Clarithromycin, or Minocycline alone.

How can I protect myself from this infection?

To protect yourself from contracting an infection with M. marinum:

Avoid fresh or salt water activities if there are open cuts, scrapes, or sores on your skin, especially in bodies of water where this bacterium is known to exist.

If you have a weakened immune system, you can reduce the risk of infection by carefully covering cuts, scrapes, or sores during fresh or salt water activities and while cleaning fish tanks or handling, cleaning or processing fish.

Wear heavy gloves (leather or heavy cotton) while cleaning or processing fish, especially fish with sharp spines that may cause cuts, scratches, or sores to the hands and skin. Wash hands thoroughly with soap and water after fish processing or use a waterless cleanser.

Wear waterproof gloves while cleaning home aquariums or fish tanks. Wash hands and forearms thoroughly with soap and running water after cleaning the tank, even if gloves were worn.

Ensure regular and adequate chlorination of swimming pools to kill any bacteria that may be present.

Thursday, May 20th, 2004, 07:30 PM
Mycobacterium Marinum
Last Updated: January 4, 2002 Rate this Article
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Synonyms and related keywords: fish tank granuloma, swimming pool granuloma, fish fancier's finger

Author: Raphael J Kiel, MD, Associate Professor of Medicine, Wayne State University School of Medicine; Associate Program Director, Head of Infectious Disease Section, Department of Internal Medicine, Oakwood Hospital

Raphael J Kiel, MD, is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine, American Geriatrics Society, American Medical Association, and American Medical Informatics Association

Editor(s): Klaus-Dieter Lessnau, MD, FCCP, Clinical Assistant Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, Pharmacy, eMedicine; Aaron Glatt, MD, Associate Dean and Professor of Clinical Medicine, New York Medical College; Chairman, Department of Medicine, Our Lady of Mercy Medical Center; Eleftherios Mylonakis, MD, PhD, Graduate Assistant in Medicine, Instructor in Medicine, Division of Infectious Disease, Massachusetts General Hospital, Harvard University; and Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine; Chief, Infectious Disease Division, Vice-Chair, Department of Internal Medicine, Winthrop-University Hospital

Background: Mycobacterium marinum is an atypical Mycobacterium found in salt and fresh water. M marinum infection occurs following skin trauma in fresh or salt water and usually presents as a localized granuloma or sporotrichotic lymphangitis. This pathogen is classified in Runyon group 1 and is a photochromogen, which means it produces pigment when cultured and exposed to light. Culture growth occurs over 7-14 days and is optimal at 32C.

Pathophysiology: M marinum infection occurs following trauma to an extremity that is in contact with an aquarium, salt water, or marine animals. Exposure to M marinum via swimming pools is rare because most pools are chlorinated. The organism grows better at 32C; therefore, cooler extremities are affected more often than central sites. M marinum rarely disseminates, except in the setting of a severely immunosuppressed patient.


In the US: Infections caused by M marinum are rare but well described in the literature. Estimated annual incidence is 0.27 cases per 100,000 adult patients. Of the approximately 150 cases described, most are case reports of cutaneous infection; however, some describe osteomyelitis, tenosynovitis, arthritis, and disseminated infection. M marinum is ubiquitous and is found more often in salt water than in fresh water. Individuals who fish or work with aquariums have an increased risk of exposure. Nosocomial infection has never been described.
Internationally: International incidence and prevalence are unknown due to lack of surveillance.

Infection with M marinum responds slowly to appropriate antibiotic therapy. Patients may require treatment for 2 weeks to as long as 18 months.
Infection may result in persistent ulceration, draining sinuses, or septic arthritis. Aggressive M marinum infection may cause extensive osteomyelitis and amputation of the involved digit.
Reports describe dissemination to the bone marrow and visceral involvement; however, the reports do not include deaths directly related to M marinum infection. Patients with acquired immunodeficiency syndrome have been reported to have disseminated M marinum infection.
Race: No known racial predilection exists.

Sex: No known sex predilection exists, and infection in men is linked to occupational exposures.

Age: No known age predilection exists. CLINICAL Section 3 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography


Infection often follows abrasions to an extremity occurring in nonchlorinated water. Fishermen, oyster workers, swimmers, and aquarium workers are predisposed.
A papule or nodule initially appears at the site of trauma. This nodule subsequently may ulcerate and involve the local joint or tendons.
Localized pain and induration are common. Fever, localized lymphadenopathy, and systemic infection rarely are observed, with the exception of immunosuppressed patients.
The incubation period of M marinum is about 2-3 weeks.
The localized lesion can increase slowly over several months.

A papule or bluish 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.
In 25-50% of patients, the nodules proliferate along the path of lymphatic drainage in a sporotrichotic type of distribution.
Patients may have deeper involvement, with tenosynovitis, septic arthritis, and osteomyelitis of the underlying bone. Dissemination to the bone marrow and abdominal viscera rarely develops.
An upper extremity is affected in nearly 90% of cases. Patients also can present with an erythematous plaque on their hands.
Most patients have a tuberculin skin test of less than 10 mm of induration.
Causes: Infection is caused by inoculation with M marinum. Individuals who are at increased risk for infection are as follows:

Fishermen and workers who process saltwater fish
Workers who clean saltwater aquariums
Immunocompromised patients (increased risk of disseminated infection)
Home aquarium owners
DIFFERENTIALS Section 4 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Mycobacterium Chelonae
Mycobacterium Fortuitum
Mycobacterium Gordonae

Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Lab Studies:

Cultures may grow nonmotile acid-fast bacilli in 7-14 days, with optimum growth at 32C.
The organisms are photochromogen (Runyon group 1), producing pigment only when exposed to light.
No niacin or nitrate production occurs; urease is produced, but the organism is a weak producer of catalase at 25C.
Even on repeat cultures results may remain negative.
Imaging Studies:

Obtain radiographs of the infected area to evaluate for evidence of osteomyelitis.
Consider a CT scan or MRI of the infected area if tenosynovitis or deeper infection is suspected.

Surgical drainage of skin lesions often is unnecessary; however, if diagnosing deeper infection, drainage is indicated.
Histologic Findings: Younger lesions show epidermal hyperkeratosis, mixed inflammatory response, or, possibly, frank suppuration. Older lesions may present as organized granulomas; however, caseation is uncommon. Organisms are acid fast and may have a transverse banding pattern.
TREATMENT Section 6 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Medical Care: Treatment usually is medical with bacteriocidal agents. Duration of therapy is empiric, with recommendations to continue therapy for 4-6 weeks following clinical resolution of lesions. Treatment of some infections may last 18 months or longer. Spontaneous resolution has been reported.

Surgical Care: Surgical drainage of skin lesions often is unnecessary. For deeper infection, drainage is indicated.

Consultations: An infectious disease physician can establish the diagnosis and suggest management.


Thursday, May 20th, 2004, 07:34 PM
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