Urinal infection after 23 years of renal

My father age 64 years has undergone renal transplant in 1993. My uncle had donated his kidney to my father. He took good care of his transplanted kidney. But due to heavy medication his arteries are getting blocked due to calcification . After renal transplant he had undergone by pass surgery and operated for his lower limbs . Recently in September 2016 his BP rose to 210 -120 . He was admitted to hospital where he was treated for BP after few weeks he stopped urinating again admitted but this time he was catherised and diagnosed with clots in bladder for which he was irrigated heavily. His creatinine 2 now. Presently problem is that he is having hernia near kidney and due to urinal infection he can't opt for surgery. Urine culture is showing significant growth in colistin ( sensitive) and other component as resistance . Puss count is 3-4 .and Colony count is 10^5 What should we do . He is having antibiotics for last 8 weeks firstly via IV than Injections now orally.