Patient has active mrsa infection since surgery 1 month ago. surgeon wants to set the fracture with titanium next week. won't this aggravate the mrsa?

Possibly: Mrsa infection in one part of the body does not mean that it will spread to another area, but that is a possibility. If one surgery has already developed a MRSA infection, i would be hesitant to implant a plate into a fracture in the same patient. Many fractures can be treated with an external fixation device, rather than an internal plate. But this has some risks as well. Check all options.

MRSA: As long as the patient is in good health other than the infection and is on the proper antibiotic regime then a good wash out and reset with titanium should do well. This is done everyday with infections and most will heal.