Freezing and transporting poop
June 9, 2022 7:26 AM Subscribe
With my doctor's approval, I will be doing home fecal transplants. My niece is going to be my donor. But there are logistical challenges. (Details maybe not for the squeamish?)
My niece (who has been fully screened) is still in diapers so my brother will be scraping the poop into ice cube trays and stick them in his freezer. I will be there to pick up the samples on the day that she 'produces' them.
However, we live 2+ hours away and 45 minutes of that is a ferry boat ride where the car needs to be turned off so using it as a power source may be dubious.
Once we get it home, the poop will be stored in a separate freezer that will be set to its coldest setting until use.
The questions are:
1) How do we freeze the poop and keep it frozen during the trip? We are wondering about dry ice? Is there a simpler way? Would a cooler and ice packs keep frozen poop in a frozen state?
2) How big a deal is it, if the poop is very cold rather than frozen for those two hours in terms of bacterial die off? Hypothesizing is great but I'd love to know the logic behind it.
Again, my GI doctor is totally in favor of this, and offering great advice, but because this is a bit of the wild west, we're having trouble finding helpful answers on the internet.
My niece (who has been fully screened) is still in diapers so my brother will be scraping the poop into ice cube trays and stick them in his freezer. I will be there to pick up the samples on the day that she 'produces' them.
However, we live 2+ hours away and 45 minutes of that is a ferry boat ride where the car needs to be turned off so using it as a power source may be dubious.
Once we get it home, the poop will be stored in a separate freezer that will be set to its coldest setting until use.
The questions are:
1) How do we freeze the poop and keep it frozen during the trip? We are wondering about dry ice? Is there a simpler way? Would a cooler and ice packs keep frozen poop in a frozen state?
2) How big a deal is it, if the poop is very cold rather than frozen for those two hours in terms of bacterial die off? Hypothesizing is great but I'd love to know the logic behind it.
Again, my GI doctor is totally in favor of this, and offering great advice, but because this is a bit of the wild west, we're having trouble finding helpful answers on the internet.
Best answer: Putting it directly on ample dry ice and storing it in a well-insulated cooler with dry ice (in a well-ventilated area!) is the best bet. Dry ice is (basically) the same temperature as the -80ºC standard for fecal sample storage, and -80ºC is better than -20ºC for preserving bacteria (-20ºC is about as cold as your freezer on max).
Depending on how long you need to store the samples for, keeping the dry ice stocked isn't too expensive. A few days to a couple of weeks can be managed with $50 worth of dry ice if you have a good cooler.
posted by jedicus at 7:53 AM on June 9, 2022 [7 favorites]
Depending on how long you need to store the samples for, keeping the dry ice stocked isn't too expensive. A few days to a couple of weeks can be managed with $50 worth of dry ice if you have a good cooler.
posted by jedicus at 7:53 AM on June 9, 2022 [7 favorites]
Best answer: I just got my mind blown finding out you can order dry ice packs that you activate in water at home, so just order your brother a sufficient quantity of those and an insulated lunchbox with a top mesh compartment so he's never putting fecal matter into his home freezer.
These are meant for shipping and I have received shipments with dry ice, it lasts for several days.
posted by Lyn Never at 8:16 AM on June 9, 2022
These are meant for shipping and I have received shipments with dry ice, it lasts for several days.
posted by Lyn Never at 8:16 AM on June 9, 2022
Best answer: Dry ice will keep it frozen but keeping dry ice in a car with the windows closed for 2+ hours is potentially dangerous, so keep that in mind. You don't want to suffocate!
Will the cubes even be fully frozen if you get them on the day they are produced? You might be better off just bringing the fresh poop home and then putting it in your own freezer.
Repeated freeze-thaw cycles are almost certainly going to kill more bacteria than letting the fresh poop sit around for a few hours. I've never worked with fecal transplants (and it's a long time since I worked with any kind of live cells) but in general you get the best preservation if you freeze things quickly and keep them as cold as possible.
I think the ideal way I'd try and do it would be to get some liquid nitrogen (or dry ice if that's not possible), go out to your brother's house, wait for your niece to make a "deposit," scrape it into little screw-top test tubes and pop those in your liquid nitrogen (or dry ice) container. Liquid nitrogen is great for freezing things really, really quickly. Dry ice is a lot easier to get, though, and almost as good for this purpose.
The main thing is to freeze it as cold as possible as quickly as possible and KEEP IT cold.
posted by mskyle at 8:17 AM on June 9, 2022 [2 favorites]
Will the cubes even be fully frozen if you get them on the day they are produced? You might be better off just bringing the fresh poop home and then putting it in your own freezer.
Repeated freeze-thaw cycles are almost certainly going to kill more bacteria than letting the fresh poop sit around for a few hours. I've never worked with fecal transplants (and it's a long time since I worked with any kind of live cells) but in general you get the best preservation if you freeze things quickly and keep them as cold as possible.
I think the ideal way I'd try and do it would be to get some liquid nitrogen (or dry ice if that's not possible), go out to your brother's house, wait for your niece to make a "deposit," scrape it into little screw-top test tubes and pop those in your liquid nitrogen (or dry ice) container. Liquid nitrogen is great for freezing things really, really quickly. Dry ice is a lot easier to get, though, and almost as good for this purpose.
The main thing is to freeze it as cold as possible as quickly as possible and KEEP IT cold.
posted by mskyle at 8:17 AM on June 9, 2022 [2 favorites]
(Those "dry ice packs" Lyn Never linked - I think they're "dry" "ice packs" not "dry ice" "packs".)
posted by mskyle at 8:20 AM on June 9, 2022 [9 favorites]
posted by mskyle at 8:20 AM on June 9, 2022 [9 favorites]
Crap, you're absolutely right. I got excited.
posted by Lyn Never at 8:23 AM on June 9, 2022 [1 favorite]
posted by Lyn Never at 8:23 AM on June 9, 2022 [1 favorite]
Response by poster: This is super helpful already. To answer the question of why freeze at all: we will do one "fresh" transplant at my brother's house but I need to do a transplant a day for the first two weeks. The goal is to freeze enough additional samples that I can do more transplants at home during the week. We'll then return to my brother's house the following weekend to rinse and repeat. It apparently takes a village to arrange a poop transplant...
posted by jeszac at 8:33 AM on June 9, 2022
posted by jeszac at 8:33 AM on June 9, 2022
Best answer: Can the donor visit you at home and produce the samples there? (Edited to add, oh, samples on a ferry is easier than a toddler on a ferry. Like crossing the river with a fox, a goose and a bag of beans!)
posted by zepheria at 9:49 AM on June 9, 2022 [1 favorite]
posted by zepheria at 9:49 AM on June 9, 2022 [1 favorite]
Best answer: Dry ice could keep the samples frozen solid, provided you have enough of it to surround the samples for the entire trip. You'll need a very well insulated container, and a good amount of dry ice (consider doing a trial run first to see how long it takes to evaporate in your test container). If you can get your hands on a small styrofoam shipping box (including a tightly fitting lid) that's probably the best option since that's how things on dry ice are safely shipped to labs. Also if you happen to know any people who work in biology-related labs, it's likely that they can just grab you one of those boxes instead of throwing it out. You could throw that box inside a big cooler to be extra safe but dry ice will usually last a pretty decent amount of time (several++ hours) in the styrofoam boxes alone. If you only have a cooler I'd test it first and see how long it takes to disappear. A very well insulated container will also minimize safety risks from the carbon dioxide gas.
Regular ice packs may or may not be enough to keep the bacteria alive, it depends, but won't keep the samples frozen. You could ask your doctor if there's any kind of sterile buffer liquid you could use that might improve viability of the samples, particularly if you can't keep them frozen (these are often used in an academic context but may not be possible in a medical context) but I'd go the dry ice route if possible.
posted by randomnity at 2:12 PM on June 9, 2022
Regular ice packs may or may not be enough to keep the bacteria alive, it depends, but won't keep the samples frozen. You could ask your doctor if there's any kind of sterile buffer liquid you could use that might improve viability of the samples, particularly if you can't keep them frozen (these are often used in an academic context but may not be possible in a medical context) but I'd go the dry ice route if possible.
posted by randomnity at 2:12 PM on June 9, 2022
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posted by amtho at 7:50 AM on June 9, 2022 [1 favorite]