Great info here. What symptoms did your chickens have who got sick from the soggy compost pile?When I have a hen droopy and not eating, obviously not well but not showing definite symptoms to point to a diagnosis, I go ahead and start a round of a broad spectrum antibiotic which I keep on hand. I get mine here. https://www.kvsupply.com/Search.aspx?query=Fish Mox 250Mg 60Ct
I use the penicillin and amoxicillin alternately, but give just the one for the full ten day treatment, 250mg once a day or divide it in half and give morning and night. It's up to you.
I checked at Tractor Supply last week to see what they had, and they carry injectable penicillin.
It's so hard to diagnose a chicken and there are no shortage of avian disorders and diseases to choose from. As often as not, an antibiotic will cure the patient, but you may never know with certainty what was wrong.
I've had several bouts of bacterial infections I've traced back to a soggy, stagnant compost pile where the antibiotic effected a definitive cure. EYP isn't always what makes a hen sick.