catheterization

Aloha from Australia, 
we have a son (5yrs) with spina bifida. He is happy and well, walks alright and since he takes the mms his whole body improved and he seems to get more function in the lower body.
His urine has to be catheterized and out of that reason he takes daily antibiotics (cephlalexin)  to stay off kidney infections and UTIs.
We believe the mms/cds can replace the antibiotic intake. 
How much of the mms/cds does my son have to take daily to replace antibiotics and keep his bladder and kidneys healthy?
Thank you!