Kidney damage will be assessed by the Value of Serum Creatinine
is advocated if Serum Creatinine levels are too high.But,it will be decided by Nephrologist
Regarding Staph infection,you can shift to another Antibiotic like Clindamycin
which does not affect the kidney.
Please consult your treating doctor and discuss regarding alternative antibiotic as infection may also aggravate kidney damage.
Wish him speedy recovery