Intermittent bladder catheterization is a procedure performed by many people due to 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. Occasionally "sterile technique" is used which means all equipment used, including gloves is sterile.
No matter which technique you use, if you re-use catheters, it is important to clean them between uses.