Post Surgical - VRE Infection, Klebsiela & Mouth Sores

Family member, male, age 60, rheumatoid arthritis, recent colectomy, at home 1 month post surgery.  Diagnosed with VRE after gallbladder removed last year.  Currently testing positive for VRE.   Released from hospital while still suffering with sore throat, mouth ulcerations that aren't responding to antibiotic treatment.  He is being seen by day nurses at home.  Found out yesterday the bladder infection he has been diagnosed with and on antibiotics for is Klebsiela so severe it is labelled as septic.  I am trying to link the VRE and Klebsiela Infections to the mouth ulcerations and wonder if there are suggestions to help him get back on track recovery wise.  I don't see a like between Klebsiela and mouth ulcerations but see that mouth ulcerations in VRE are seen.  I also see that mouth ulcerations in CMV (another hospital plagued virus) is more commonly presented with not only mouth ulcerations, but esophagus ulcerations.
Any suggestions would be helpful.  I feel we need a "big bullet broad base antibiotic" but wonder what that should be to help him.  He is also diabetic.  His immune system is very suppressed due to all the conditions.
He is depressed, barely eating, drinking not talking due to the pain in his mouth.
Any hints, tips questions we should be asking of our medical doctors?
Thanks