My personal experience with this infection sent me in search of information and inspired this article to hopefully pass on some helpful interesting information, increase awareness and prevent you from contracting this infection.

My Story

I was messing around in my horse corral . I was in there quite a while this time aquascaping and playing with the rocks.  When I woke up in the morning I noticed an inflamed elevated area on the underside of my forearm about 6 cm in diameter.  On closer inspection I noticed a very tiny scratch maybe 1 cm in length and as fine as a piece of thin thread, originating from a tiny red dot smaller than the head of a pin.  I did not remember scratching myself, being stung or bitten by anything in my tank.  When I got to work and put my arm down on the desk to write... OUCH!  It really hurt to have any pressure on it at all.

I am an RN, specializing in High Risk Obstetrics.  What do I know about skin infections.  I know just enough to panic myself and not enough to be useful.  I showed it to one of my Co-workers who felt compelled to tell me about a friend of hers who was hospitalized for 6 weeks with that flesh eating bacterial disease.  He almost lost his leg.  I'm sure she meant well.  I had myself minus one arm, practically dead and buried in a matter of minutes.

I showed this lesion to anyone who walked by that would give me the time of day, all obstetrical nurses and docs.  They all thought it was probably nothing to serious, definitely nothing deadly maybe a bug or spider bite.  I got advice from warm soaks with Epsom salt to antibiotic ointment to oral antibiotics.  I was relieved and decided to use some antibiotic ointment and soak it.

Well its 6 months later and there are still traces of it on my arm.  It very gradually over about 2 months diminished in size to about 1 cm in diameter with a small whitish center and became painless.

About 6 weeks ago a doc who specializes in infectious diseases and happens to be very reputibable as well as a really nice guy, just happened to move into the office down the hall from my nurses station.  He was looking at the newspaper one morning at the station and so I took the opportunity to get his opinion.  I showed it to him and told him how I thought I got it.  He said it was most likely an infection from Mycobacterium marinum, a bacteria commonly found in aquariums, especially marine aquariums.  He suggested I aspirate it with a needle and take an antibiotic Biaxin 500 mg twice a day for 2 to 4 weeks.  Well I hate antibiotics and the thought of poking it with a needle made me nauseous, so I didn't do anything at the time.

I recently came down with a bad cold and ended up with a secondary infection in my lungs and sinuses, like I so often do because of my asthma.  My doc always insists I take antibiotics.  He prescribed Biaxin 500mg twice a day for a month.  The now small lesion on my arm had stopped improving so I decided as long as I was going on antibiotics for my sinuses I should also do the needle aspiration and give this every chance to heal.  I got one of my colleagues to aspirate it.  The tiniest amount of thick white fluid came out.  Within 2 days of the antibiotics and aspiration it was almost gone.

I have almost finished my month of antibiotics and all that is left of the lesion is a small pinkish scar.  Now for the disease.

Etiology

Mycobacterosis is a relatively rare infection of the skin acquired from a waterborne pathogen called Mycobacterium marinum.  This bacteria is a relative of the organism that causes tuberculosis and leprosy in humans.  It is found throughout the world in the freshwater and saltwater of home aquariums, swimming pools, oceans, beaches, rivers, lakes, natural bathing pools and old wells.  M. marinum is rarely associated with swimming pools today due to the almost universal use of chlorine.  Other vectors for this organism include saltwater or freshwater fish, dolphins, shrimp, snails and water fleas.

Mycobacterial infections are one of the few diseases that humans can acquire from wild caught as well as aquacultured ornamental fish.  More than 150 marine and freshwater fish species throughout the world have been found to host this bacteria, due to its ability to survive and thrive under many various conditions.  Research has shown that infected fish shed the bacteria into the water and that water and soil as well as the fish themselves can host the bacteria.

In fish this is a chronic slow developing disease.  The clinical signs and symptoms of infection would be unlikely to all occur in a single fish and include lethargy, anorexia, weight loss, edema of the abdomen, loss of scales, bulging of the eyes, skin ulcerations, nodules in muscle tissue, and loss of bright coloration.

The diagnostician may have difficulty identifying this disease due to its slow growing nature.  The disease develops more rapidly in warm waters due to the optimum temperature range of M. marinum being 76 to 82 degrees F.

Captive fish are at greater risk of being exposed to this bacteria and are more severely affected when they do contract it than fish in the wild.  It has been estimated that about 15% of some species of aquarium fish have mycobacterosis.  Stagnant water that is not well circulated or changed periodically is thought to have large amounts of this bacteria present.  It is unusual to find it in the fast moving waters of streams and rivers.  There are several conditions that are ideal for the growth of this organism in the commercial aquaria.  These include the relatively longer life span of captive fish than fish in the wild, stress from crowding and poor water quality, and the feeding of live or raw fish.  Treatment options are few because the mycobacteria that infect fish are mostly resistant to the typical antimycobacterial drugs.

Clinical Manifestation and Pathophysiology in Humans

M. marimum is usually introduced to the human through a break in the integrity of the skin like a scratch, cut, puncture, or abrasion, usually on the hands or arms.  However a site of prior injury is not always present.  At the site of entry the organism usually causes microscopic localized nodules called granulomas to form.  The granulomas gradually increase in size becoming visible as small pink to violet papules that may be painful to touch.  They may progress to shallow ulcerations and ooze serosanguineous fluid or pus, or develop a verruccous surface and eventually cause the development of scar tissue.  The lesions are most frequently solitary but can occasionally develop into multiple granulomas forming an acceding line along a lymphatic vessel that drains at the site.  For a photograph of the actual infection see the following sites:

University of Iowa Department of Dermatology:

• http://tray.dermatology.uiowa.edu/MMarin01.htm
• http://tray.dermatology.uiowa.edu/MMarin02.htm
• http://tray.dermatology.uiowa.edu/MMarin03.htm

http://www.adam.com/imagepage/2337.htm

This is an uncommon infection that is almost always localized and curable in individuals with a healthy and intact immune system... immunocompetent!!  The skin is the most common site of infection.  The bacteria is not prolific at normal body temperature which is why usually it remains localized to the cooler surface of the skin.  In rare instances the joints may be affected with resulting septic arthritis and even osteomyelitis The infection rarely disseminates, however when it does it is typically in individuals who are immunocompromised with AIDS,kidney disease, diabetes, liver dysfunction or on chemotherapy.  There have been reports of life threatening systemic infection and even death in these individuals who are severely compromised.

Host to host transmission is not known to occur.

The incubation period is usually long but can be anywhere from 2 days to 6 weeks.

Incidence

0.27 per 100,000 patients in the US

Risk Factors

Mycobacterosis is seen all over the world, most commonly in individuals who have exposure to freshwater, saltwater and fish.  This includes anyone who owns or maintains a freshwater or marine aquarium, boaters, fisherman, water sports enthusiasts, aquaculturists and anyone who works with or handles fish.

It is seen more commonly in adults and has no propensity to any particular race or sex.

Treatment

In the immunocompetant individual the infection will spontaneously resolve in 24 to 36 months with residual scar tissue formation.  Initial treatment is usually with antibiotics.  From the review of literature I did there seems to be no treatment of choice recognized.  However, the literature indicates traditionally the combination of the use of 2 antibiotics: trimethoprim-sulfamethoxazole, minocycline, or Rifidan, in conjunction with Myambutol, and more recently monotherapy with Biaxin 500mg twice a day for 2 to 4 weeks.  Treatment with anti-tuberculosis drugs was mentioned as well as possibly needle aspiration, incision and drainage, or surgical excision of the lesion.  It can take up to 1 to 3 years to cure.

Heat can also be used as an additional therapy.  This organism is unable to thrive in the presence of heat.  In addition warm compresses or soaks will increase the blood flow to the affected area, bringing with it increased amounts antibiotic and white blood cells which help to fight infection.

Prevention

Since this is a difficult infection to treat a few precautions are defiantly worth the effort.  Some simple preventive measures like washing the parts of your body well that have been in contact with any of the above listed sources of this infection.  Avoidance of these sources especially if you have cuts or scratches.  This may be unrealistic so incorporating the use of gloves and long tools would be beneficial.

In conclusion I urge you to exercise caution working in your aquariums and handling your fish.  If you do notice any lesions or sores and especially if you are one of those individuals with a weakened immune system please seek medical attention.  Had I known this at the time I would have sought treatment sooner.  I hope you found this informative and helpful.