Usually the catheter is changed about every two weeks, and the tubing and leg bag are washed out daily with diluted chlorine bleach and hung to dry. There is much information around about how to prevent infections that occur in patients with MS, and there is still a fair amount of disagreement about the very best way to do this. First, it's really important not to get dehydrated. When the urine becomes concentrated and flow slows down, the bacteria grow and infections often occur. Of course, that's difficult, particularly when traveling or attending a family reunion or other important social function.
Sexual activity is another thing that sometimes predisposes to infections.
One thing that does help, however, is making sure to urinate after sex, to wash out the urethra and empty the bladder. Well, if you look at the scientific literature, there have been studies on this with spinal cord injury, and the conclusions are that it does nothing to prevent symptomatic infections. Despite this, many individuals with MS believe that cranberry juice or Vitamin C significantly reduce infections. And Vitamin C will cause diarrhea when taken in large doses. If you are having frequent infections, it's important to find out why this is occuring, and to treat the problem specifically and directly.