Maybe some more specifics of the situation.

My friend is taking B cell depleting medicines as an MS treatment.
The infection started as a Cellulitis infection near the groin area. There are no clues as to how it got in there. Speculation is some kind of micro cut, and skin bacteria got in there. From there it moved to the back of the leg/knee and the front lateral knee area. The original groin area seems to be getting under control and created its own drainage. The other spots required intervention to create a drainage path.
At least for now, the infection has been contained to the right leg.
Not clear if the Pseudomonas is hospital acquired, or if the original infection is different. But it's the only thing they have been able to grow so far.
The medical/hospital team is very good, we get CT scans as we suspect the infection has moved.
I'm just concerned that this has been going on for a few weeks, requiring more and more pain management, and no path to resolution. With this kind of thing probably being unique to each individual, I just wanted to check if there were other similar situations we could draw some experience from.