Question

[Connor Elliott]

What are your guises thoughts on bacterial infections growing immunity’s to medication? Should that be something I should worry about?

[Daniel]

It certainly could happen. But two factors would work against it in the long run. The drug resistant bacteria would likely have a harder time competing against non drug resistant bacteria if there were no drugs present (which I would presume that your aquarium does have some time periods without drugs in it).

And if the drug resistant bacteria were to kill its host, it would perish also or at least be back to competing against non-drug resistant bacteria in a presumably un-medicated aquarium.

If drugs were frequently used, it would definitely have long term viability.

 

[Kirsten]

I agree with @Daniel. Drug-resistant bacteria takes time and countless generations to evolve to resist whatever it is you're throwing at them. So unless you're dosing with the same antibiotic every week as a preventative, there wouldn't be that selection pressure to breed superbugs.

I would say those conditions are possible for large fish farms, but for the aquarium trade they sometimes just use brackish water to raise fish (especially if they're in a country where fresh water is more precious than seawater). That usually keeps most freshwater pathogens or parasites at bay, though they could contract illnesses that thrive in brackish water. But when they're sold to the wholesaler or retailer or customer, they go into freshwater, which can knock out those brackish illnesses.

[Hobbit]

I honestly worry about this with the co-op’s brief med dose regimens. (Love you co-op, don’t get me wrong!) The reason we’e supposed to take strep antibiotics, for example, for 10 days even though we feel better after 2, is that the likelihood of some bacteria being able to survive one or two doses of antibiotics is a lot higher than the likelihood any could survive 10. If we only kill the weak bacteria and let the slightly stronger bacteria survive, the slightly stronger buggers get free real estate to spread themselves around. More bacteria = more chances of another mutation that will allow it to survive three doses of antibiotics, and then four, etc. I worry that by only giving fish one dose of antibiotics, it’s providing a stepping stone in a bad direction.

Here’s a video Harvard put out several years ago where they set up an experiment in this regard, using stepping stone doses of antibiotics. Under otherwise ideal growing conditions, it only took E. coli 11 days to stack up enough mutations to survive 1000x the dose of antibiotics it would normally be able to withstand.

All that said, everything in life (especially in medicine) is a trade-off. There are no treatments without consequences, both acute and long term. I think it’s good to avoid using antibiotics when we can. But as others have said, because our aquariums are closed systems where any superbug is likely to die before it ever meets another fish, the risk is much lower than using antibiotics on farms or in humans.