I usually put bread into the fridge after buying because I don’t eat it often (use a toaster to warm up). I was wondering how long you can typically keep bread good in a fridge for before it goes bad?
Related, is it possible for the bread to go bad without any visable/perceivable sign of some sort of pathogen growth on it? I have a loaf that’s been in there for a month that I’m curious if it’s still ok to eat or not.
Bread will taste stale long before it goes fuzzy in the refrigerator. Freezing may be a better solution for you. You can either get a couple slices out the day before, or microwave for 15 seconds.
I don’t know of any pathogen that grows in bread that won’t either look fuzzy or smell bad.
I agree.
It must be stored in a completely air-tight container. Even zipper-style freezer bags aren’t totally secure.
The issue is freezer burn if you have a frost-free freezer.
Still, though, I always keep bread in the freezer. It lasts really nicely for a week; longer if I use high quality freezer bags.
And lightly toasting bread is a great way to bring it back to life.
While I was composing my long response, others have posted. However …
There are several issues here. One of the most important is what kind of bread it is. “White” or “wheat” (or other dark bread).
The thing that has the greatest effect on edibility of refrigerated bread is whether it has dried out or not (directly related to issues of freezer burn). Bread (or other stuff - cooked rice is a good example) that’s in the fridge for a while dries out, just like anything in the freezer does. Once the bread’s dried out enough, it will not make satisfactory eating. However, white bread can be used to make croutons (cube it and heat in a low oven until lightly browned). 
I live alone, and I routinely keep bread for several weeks to a month (sometimes more, but not often) in my fridge. However, all the bread I eat is either wheat or rye (including pumpernickel, which some people call dark rye). Further, because of the drying issue, I always put another heavy plastic bag (saved bread/bun bags) around it. That dramatically reduces the moisture loss. Without the extra bag, ten days is about as long as the bread will make satisfactory (i.e., enjoyable) sandwiches - and I refuse to eat a sandwich with dried out bread. I doubt that white bread will make ten days, but ICBW.
As to the issue of going “bad”, signs of mold culture will be highly visible on white bread. It’s less so on dark bread, which means that it’s something to watch for more carefully. Even though rye bread bought in the store has a high percentage of wheat flour in it, eating moldy rye bread could be dangerous to your health (depends on the species of mold growinig there; don’t take chances).
I have found that putting bread in the fridge instead of the cupboard, a breadbox or other room temperature place makes it get hard faster- something to do with the glutens.
That was borne out by what I learned in cooking classes later.
As EJsGirl says, it is the gluten, or so I’m told. Water combines with the gluten and the starch grains during baking to give the bread its texture, and it goes stale as the water separates from everything else. (Stale-tasting isn’t the same as dry.) Refrigerator temperatures are close to ideal for that, so bread will start to get stale faster than at room temperature. Of course the warm bread will grow mold pretty soon, so freezing is best if you want to keep it a while.
Depends. Put it next to the beer and dip and before you know it, it’ll very often have turned into an irresponsible party animal, as bad as bad can be. Put it on the shelf with the milk and Mom’s apple pie and it may stay good forever.
How long can vs. How long do?
We’ve been known to have bread in the fridge for up to a couple of months. After a few days, it’s bad for sammiches, but you can still get good toast out of it as long as there’s no green spots. Once it goes green, it then goes in the bin (though once when I was really poor, I have actually pulled the green spots off and eaten the rest of the toast)
Every loaf of bread that I buy goes into the freezer immediately. Leave individual slices on the counter for ten minutes or so, or toast it, and it’s like it’s fresh.
Lasts for weeks.
I usually buy white bread, but I know that whole wheat behaves the same.
It’s a lot easier to smear peanut butter & jam on frozen bread - no divots! Then you tuck it in a bag, and by lunchtime - voila! - nice fresh squishy sandwich!
The fridge just makes it hard and cardboardy and the pantry turns it into a Chia pet.
According to “The Science of Cooking” it’s not a case of water separating from everything else. What happens is that starch molecules change from the form they have after cooking into a crystaline form, and absorbs water in the process. This process works the fastest around four degrees C, so keep bread out of the fridge if you don’t like it stale.