biologist / bacterial decon question
I have a tank that has a spore forming bacteria in it. This bacteria does not harm fish, but when a shrimp molts it seeds any small wounds, goes anaerobic and kills the shrimp. I suspect it is either a species of clostridium or bacillus (rod in pairs, not consistently gram positive or gram negative, leading me toward clostridium). Whatever it us, its nasty and nearly 100% lethal. If you are reading this, and find yourself lost in the terminology about the bacteria itself, feel free to ask questions and learn from the thread, but please donít try to offer help. I am looking for the opinion of another person with a deep understanding of the elements of this situation Ė like an aquatic biologist, a technician who does decon for a hospital or clinic, or someone who has some real experience with these insanely tough species of bacteria. As you can probably tell I have a fairly technical background myself. I am a med student. I can identify the bacteria, but that doesn't mean I know how to remove it from an aquatic environment.
I realize I can protect the shrimp that are currently in the tank with metronidazole as long as I keep them on it. But seriously, who's going to keep a tank on prophylactic antibiotics forever? That's just not feasible (nor a judicious use of antibiotics). Also, I'm down to 3 shrimp. I have fish in the tank, so I will have to figure out what to do with them during the interim but here is my question, to get rid of a spore forming bacteria, and its spores what would one need to do? And, yes, I'm certain this is a spore former. It came from the substrate of one of my old tanks, if you saw my decontamination procedure, (rinsing, boiling, plus allowing to completely dry. I didnít autoclave it, last time it stunk up the lab too much.) only a spore would get past that. Since I know I will be asked, the shrimp sometimes change color, sometimes they turn pale. Mostly movement slows to a crawl (no pun intended) likely a toxin mediated effect. Death occurs within 24-48 hours of molting, the last five or so hours they are in some type of shock and can barely stand up. When I have done cultures I get a mixed infection, but gram stain from the infected shrimp shows almost all rods in pairs that inconsistently gram stain (+/-). I suspect they are obligate anearobes, and my culture methods have been aerobic thus far. So far everything is pointing to a form of clostridium. They were quasi responding to kanamycin but resistance developed; now metronidazole is the only one working. I'm at the point of just feeding it to them. Any disturbance of the substrate triggers a large distribution of spores and is followed by a die off. I miscalculated and tried vacuuming the sand in hopes of reducing the number of spores, lost 5 shrimp overnight. I'm thinking of moving the three survivors to the cichlid tank as a form of mercy. Other than three shrimp that are currently doing well no occupants are in any danger. The fish seem undisturbed by it, as it requires an open wound for entry. Again, my question isn't what to do with the occupants. It's what decontamination procedure is best for a spore based disease like this.
I am debating between two courses of action.
1. Dispose basically everything inside the tank, plus the filter and the media. Rinse the tank very thoroughly, beyond thoroughly and then establish it is a whole new aquarium. Are there any chemicals that are known to destroy spores that with enough dilution over time could render the tank safe again? Could anything be used on some of the equipment to reduce the cost of this option?
I know in medicine we use disposable everything and toss it all. No alcohol foam allowed for hand sanitation on cases of spore based disease. Must go with soap and plenty of water. But our body has an immune system the tank doesn't.
2. The longer route: removing the substrate, hitting the biofilm in the filter with a bleach, keeping it bare bottom with regular water changes and only aerobic media for a few months. Suctioning the bottom when doing water changes, and disturbing the biofilm on the plants during that time as well. Treat the tank with probiotic bacteria to help out compete the pathologic species. Eventually add new substrate in. This will allow me to remove the vast majority of the spores and take it down to a level well below what is required to cause disease without requiring me to kill all my plants and setup a temporary home for the fish as well as replace all of the equipment. After the setup is running and stable leave it shrimp free for several more months to ensure that the bacterial competition favors the other species before reintroducing shrimp.
Any thoughts on which method is most likely to succeed? Any improvements to either proposition? Iím not in a hurry, its stable. I just want a second set of neurons entering the debate that rages in my head. Preferably one that can challenge my way of thinking and add another dimension to the debate. And just in case you are tempted to ask, no I do not have access to gamma radiation.