Intermittent bladder catheterization is done by many people for a variety of urinary tract problems. It is generally done using "clean technique." This means that not all bacteria (germs) are kept from coming into contact with the person being catheterized.
Sometimes "sterile technique" is used, which means all equipment, including gloves, is sterile.
No matter which technique you use, if you re-use catheters, it is important to clean them between uses.