Tank Safety/Fish TB by Dr. Adrian Lawler

Tank Safety/Fish TB

by Adrian Lawler, Ph.D.
(retired) Aquarium Supervisor (l984-l998) J. L. Scott Aquarium Biloxi, Ms 39530
Aquarticles

Water is a well known medium for transfer of various diseases. Some fish and other aquatic organisms carry, or get, bacterial infections that can be transmitted to humans. A listing of some of the diseases transferred to humans via fish, etc. is presented in Lawler, Diseases Transmitted to Humans, (in Aquarticles' Management section), and includes Mycobacterium marinum ("fish TB"), Vibrio vulnificus, Vibrio damsela (= Photobacterium damselae), Vibrio spp., Salmonella spp., Erysipelothrix rhusiopathiae, and Streptococcus iniae. Some of the previous bacterial infections can be fatal in humans.

A new listing would be Mycobacterium chelonae, a bacterium related to fish TB, human TB, and leprosy, that can be isolated from water, soil and dust, and is also known to infect various fishes. If your fresh water supply is not treated well enough, you can be exposed to M. chelonae each time you use tap water for tank work and water changes, or for regular daily water uses. There are many records of people getting infected with this bacterium from contaminated water at hospitals (wounds from injury or incisions from surgery are infected), from taking showers in their own home, from contaminated fluids used in medicine, from contaminated insulin injections, from contaminated acupuncture needles, from aerosols from hot tubs, etc. Like M. marinum, M. chelonae is resistant to treatment and hard to cure. One report came to me of a woman with infected breasts that could not be cured after many tries, so the victim had her breasts removed deeper than the site of infection (so no M. chelonae bacteria were left in the breast area) and then had reconstructive surgery done.

Another new listing would be Mycobacterium shottsi, described in 2001, from striped bass in Virginia. In humans it is a disease similar to that caused by Mycobacterium marinum. It doesn't thrive at temperatures greater than 86° F, so it can live on humans on only extremities as a persistent rash. There is no danger of getting the disease from eating a striper; cooking the fish to 170°F for 20 minutes kills these mycobacteria.

The last new listing would be Staphylococcus aureus; Florida health officials said (2003) skin problems reported by several fishermen and at least one surfer in Volusia County were caused by a common environmental bacterium called methicillin-resistant Staphylococcus aureus or MRSA. Infections with this species are usually hospital-acquired by people with weakened immune systems; this species is also found in the home and in the workplace.

During the 7 years since the first article was written, I have received many emails about various aquatic infections (from tanks, fish, and natural waters), and I can report that about 90% of these infections were Mycobacterium marinum. The remaining 10% included Vibrio infections, M. chelonae infections, and infections of unknown origin. Based on the emails I received, the infected aquarists were mostly infected by M. marinum.

Since most people seem to be getting Mycobacterium marinum rather than another type of infection from their tanks, fish, or aquatic areas, I include procedures below to follow to seek a cure. (These steps, in general, would also apply to other types of infections.). Fish TB is related to human TB and leprosy; bacteria of this genus (Mycobacterium) are slow growing, highly resistant to antibiotics, hard to culture, and many times not recognized for what they are. There are human infections of fish TB that have persisted for up to 17 years. I have had fish TB, getting it over 40 years after I starting keeping fish tanks, probably because my immune system was getting weaker.

The secret of getting proper treatment is to find medical people who know what they are doing and have had some experience with fish TB. I present a quick summary of what has to be done to cure fish TB before it leads to a costly, long, trying infection. Do below in order indicated:

1…Get a competent doctor to take a sample from inside the infection (if nodules are easily seen, sample them). Since M. marinum is difficult to culture, sample from the center of the area that appears to have the highest bacterial activity to increase the chance of getting bacterial cells for culturing.
2…Get a laboratory that has previous experience in culturing Mycobacterium to culture the sample taken from the infection. (since Mycobacterium is slow growing, it will take 2 weeks or longer to get the culture results).
3…Have at least 2 samples cultured in case something happens to one. Since fish TB takes so long to culture, any further delays due to lost cultures or bad culture techniques will put you further into the course of the infection (infection will worsen over time), thereby making it more difficult to control the infection and taking longer to cure.
4…IF the culture comes back positive for fish TB, THEN have the laboratory KEEP the cultures from the infection so they can then run sensitivity tests on the cultures using various antibiotics to see WHICH antibiotic is BEST at killing the culture from your infection. You will then have the best antibiotic that will control the strain of fish TB that is in your body.
5…Use chosen antibiotic(s) for cure (since bacteria are resistant and slow-growing it can take a year or MORE to get a cure). They usually use the same drugs (as streptomycin (SM), pyrazinamide (PZA / PIZ), D-ethambutol (EMB), isoniazid (INH), rifampin (RIF), etc) as for human TB.
6...If the culture comes back negative for fish TB, have it tested again because the bacterium is hard to culture.
7...If second sample comes back negative, have further cultures done using a wide range of culture media to find out what types of bacteria are present. Go thru 4 & 5 to get cure.

Another method to identify the infective bacterium is to have your infected tissue sample tested for the presence of Mycobacterium marinum DNA. Make sure the sample is collected and handled properly for DNA analysis. With this method, though, you have not identified the best antibiotic(s) to treat your strain of fish TB.

IF you can recognize the initial signs of the infection, persistent itching and the appearance of small nodules under the skin at site of entry (in my case), then (as I) you have a good chance of stopping the infection quickly before the bacteria get to deeper tissues. And you want to stop it quickly so you do not have to go through a long, trying treatment. Get a doctor to use any of several methods to quickly kill the bacteria that are still shallow and more easily accessible.

Locally, I have found that dermatologists have more experience with fish TB than other doctors.

In order to prevent transfer of various aquatic diseases/parasites from natural waters to humans, or from tank to tank and/or to humans, the following safety practices should be followed:

1….Do not stick hands and arms into tanks (or go into natural waters), or handle aquatic organisms, if you have an open or recent wound.
2….Use protective gloves. We found that using shoulder-length gloves that veterinarians use while working with cows are useful in protecting arms with recent wounds while doing tank work.
3….Do not dive in a tank (or natural waters) containing Vibrio vulnificus if you have an open or recent wound or you are prone to nose bleeds. The water from a tank should be checked for Vibrio vulnificus by a microbiology lab prior to any dive.
4….Sterilize hands and arms with chlorine water (use alcohol if there are wounds) after work in one tank and prior to working on another tank, or rinse hands and arms thoroughly with city water.
5….Wash hands thoroughly (or sterilize) after handling turtles and other reptiles to avoid infection by Salmonella.
6….Never start a tank siphon with mouth suction.
7….If an injury occurs while working in a tank (or natural waters), let wound bleed freely for a while to push possible infecting bacteria back out of the body, then sterilize and protect wound.
8….Seek medical help ASAP if infection spreads (or red streaks occur), throbs, is very painful, or appears different in any way from your "usual" infections.

Conversely, you should not go into a tank with an infection that might inoculate your tank with your bacteria, and which might affect tank occupants, or you again at a later date. Clean (or sterilize) hands and arms before doing tank work.

Those people with weakened immune systems are at greater risk for getting infections. So people with AIDS, diabetes, liver dysfunction, kidney problems, or those undergoing cancer treatment, or of old age, etc. should be especially careful when working on tanks, handling aquatic organisms, or getting into natural aquatic environments.

To protect future tank occupants, break down and sterilize a tank infested with fish TB with chlorox.