Catheter-Associated Urinary Tract Infections (CAUTIs)
A catheter-associated UTI (CAUTI) is a UTI in which the positive culture was taken when an indwelling urinary catheter had been in place for > 2 calendar days. Patients with indwelling bladder catheters are predisposed to bacteriuria and UTIs. Symptoms may be vague or may suggest sepsis. Diagnosis depends on the presence of symptoms. Testing includes urinalysis and culture after the catheter has been removed and a new one inserted. The most effective preventive measures are avoiding unnecessary catheterization and removing catheters as soon as possible.
Bacteria can enter the bladder during the insertion of the catheter, through the catheter lumen, or from around the outside of the catheter. A biofilm develops around the outside of the catheter and on the uroepithelium. Bacteria enter this biofilm, which protects them from the mechanical flow of urine, host defenses, and antibiotics, making bacterial elimination difficult. Even with thoroughly aseptic catheter insertion and care, the chance of developing significant bacteriuria is 3 to 10% every day the catheter is indwelling. Of patients who develop bacteriuria, 10 to 25% develop symptoms of UTI. Fewer develop sepsis.
Risk factors for UTI include duration of catheterization, female sex, diabetes mellitus, opening a closed system, and suboptimal aseptic techniques. Indwelling bladder catheters can also predispose to fungal UTI.
UTI can also develop in women during the days after a catheter has been removed.
Patients with CAUTI cannot have some of the symptoms typical of UTIs (dysuria, frequency), but they may complain of feeling the need to urinate or of suprapubic discomfort. However, such symptoms of lower tract UTI may also be caused by obstruction of the catheter or development of bladder calculi. Symptoms of acute or chronic pyelonephritis may also develop without the typical urinary tract symptoms. Patients may have nonspecific symptoms such as malaise, fever, flank pain, anorexia, altered mental status, and signs of sepsis.
Testing is done only in patients who might require treatment, including those who have symptoms and those at high risk of developing sepsis, such as
Diagnostic testing includes urinalysis and urine culture. If bacteremia is suspected, blood cultures are done. Urine cultures should be done, preferably after replacing the catheter (to avoid culturing colonizing bacteria), then by a direct needle stick of the catheter, all done with aseptic technique, so that contamination of the specimen is minimized.
In women who have had a catheter removed, urine culture within 48 h is recommended regardless of whether symptoms occur.
Asymptomatic, low-risk patients are not treated. Symptomatic and high-risk patients are treated using antibiotics and supportive measures. The catheter should be replaced when treatment begins. Choice of empiric antibiotic is as for acute pyelonephritis. Sometimes vancomycin is added to the regimen. Subsequently, antibiotics with the narrowest spectrum of activity, based on culture and sensitivity testing, should be used. Optimal duration is not well established but 7 to 14 days is reasonable in patients who had a satisfactory clinical response, including resolution of systemic manifestations.
Asymptomatic women and men with recent catheter removal who have UTI diagnosed by urine culture should be treated based on the culture results. Optimal duration of treatment is not known.
The most effective preventive measures are avoiding catheterization and removing catheters as soon as possible. Optimizing aseptic technique and maintaining a closed drainage system also reduce risk. How often and even whether to routinely change indwelling catheters is unknown. Intermittent catheterization carries less risk than use of an indwelling catheter and should be used instead whenever feasible. Antibiotic prophylaxis and antibiotic-coated catheters are no longer recommended for patients who require long-term indwelling catheters.
Long-term use of indwelling bladder catheters increases risk of bacteriuria, although bacteriuria is usually asymptomatic.
Symptomatic UTI may manifest with systemic symptoms (eg, fever, altered mental status, decreased BP) and few or no symptoms typical of UTIs.
Do urinalysis and urine culture if patients have symptoms or are at high risk of sepsis (eg, because of immunocompromise).
Treat similarly to other complicated UTIs.
Whenever possible, avoid use of catheters or remove them at the first opportunity.