You would only get a staph infection if you followed poor hygienic practices when dealing with this. If you just wrap the feet it will not do any good. You have to drain and cut out the infection.
Get some betadyne and wash everything on the birds legs with it.
get some rubber gloves
get an exacto knife. wash the knife in betadyne
wrap the chicken in a towel
cut open the foot pad and get the core of infection out.
Wash the chickens legs with betadyne again
wrap the feet up with sterile dressing
wash your arms and throw any clothing you wore into a hot water wash cycle.
change the foot dressing once a day.
They sell Betadyne at theisen's,
Tractor supply, orshelns etc...
Then you chicken will heal and be staph free so your grandmother can be around it.
Seriously you can't just do what you want to do. you have to do what is good for the bird. You have many links with pictures provided for you to take care of this. time to put on your Big Girl Panties and get it done!!
Or just give up on the bird?
here is the best link:
https://www.backyardchickens.com/forum/viewtopic.php?id=236649