How do I get a catheter-associated urinary tract infection (ca-uti)?

Foreign body. 1) bacteria located at ou just within urinary opening get pushed up into the bladder, and can occur every time catheter is introduced. 2) everyone with an indwelling catheter will eventually get a uti, takes longer if on antibiotics, but no bladder is immune. Bacteria work their way up between catheter and urethral lining. 3) catheter can be seed for stone formation, also damages bladder lining.
By being unlucky. Foley catheters are commonly used to drain the bladder when patients are unable to void on their own. If the catheters are put in improperly or left in too long, a bladder infection may occur. They are usually treated by removal of the catheter and treatment with antibiotics.
For multiple reasons. Once a urinary catheter is placed, bacterial colonization begins as bacteria spread from the skin along the tube. Within 14 days, 100% of patients with a catheter will have a positive urine culture. This should not be treated unless symtomatic to prevent resistance. Good hygiene, proper maintenance, and early removal of the catheter will lessen the risk of uti.