I don't think its pus you're looking at. First it was an open wound so drainage happened keeping the white blood cells from encapsulating the infection and causing the harder, cheesy mass. I would get a large syringe without the needle, fill that with sterile saline (that can be had in the live...
I would use PennG injectable for the type of wound she has. It is much more likely to cover the whole system and arrive at its fullest strength. You can make certain she is getting a full dose since you would be in control.
With the type of wound she has she would have to be on a full 14 day...