Bumblefoot causes?

[smott]

I have 5 (of about 60) chickens that I am treating for bumblefoot right now. I have read the information about how to treat, and they are (slowly) healing. I would like some input about possible causes! I've read it is caused by a staphylococcal infection. I'm just looking for suggestions of things I could do differently to prevent recurrence. I have "dropping boards" underneath my roosts filled with PDZ that I clean every single day in all my coops. I rake/turn over the soil in the run areas weekly-ish, and remove any excessive poop. The vinyl flooring in one of my coops is covered with a couple of inches of hemp bedding, and the other has a mixture of Koop Clean bedding and some of the pine pellets (dissolved into sawdust form). The roosts themselves are painted 2x4's (wide side up) which are smooth without splinters. There are ramps up to them, although most of my chickens choose to jump up and down to them (the edge of the dropping boards are about 3' off the ground). I have birds in 2 different coops that have it, and they do free range in the same area every afternoon. It's very possible that they are coming in contact with sharp objects in the area that they free range, because they do go underneath the house and shed. I'm not sure if it's just opportunistic infection setting up in an existing injury? I find it odd that several of my chickens have it at the same time, and I'm suspicious if the staph bacteria is coming from a source in my soil somewhere. Is this possible? If so, is there a way to "treat" the soil to rid the area of the source of the infection? I have washed the roost boards with bleach a couple of times, but apparently they already had it and I wasn't aware until I started doing foot checks. Any info is appreciated! Pic of my Blondie getting her foot "spa" for attention!

 

[casportpony]

This is a pretty good article:
https://hari.ca/avian-care/health-monitoring/symptoms-treatment-bumblefoot-parrots/

 

[McChooky]

You don't want anything on their perch that would give mites or lice places to hide or where bacteria can grow.