I think that you need to find a different doctor for your grandmother. If she has an infection, she obviously needs antibiotics, but antibiotics will not help her heal without proper wound treatment. Take her to either a good wound center or a doctor that specializes in treating wounds. They will be up on current treatments in wounds. A big thing in wound treatment today is some kind of honey-wrap (I am sorry that I don’t have the exact name for you).
I did go thru a bad wound and was able to save my leg by going to a good wound center. I still see one of the doctors that I met there. Someone on another message board posted about the product you asked about the week I had an appointment with him so I told her that I would ask about it. This doctor specializes in wounds and his practice is made up entirely of wound patients. He has patients coming from other states to see him. When I asked him about that spray, he said it was a scam. Oxygen sprays do not work.
There are things that can slow down healing that should be checked. It is common to be anemic if you have a wound. Being anemic can slow down healing so that needs to be treated. Protein levels can be low and that also slows down healing. Besides eating more protein, a protein supplement should be added. The first wound center was checking blood and I was anemic and had low protein levels but nothing was done about either of those. I was also put on a very expensive antibiotic that was not the proper antibiotic for the infection I had.
Find a good doctor that understands wound treatment and don’t waste your money on the junk you posted.