Catheter-acquired urinary infections

Urinary tract infections (UTIs) are the most common hospital-acquired infections. Most UTIs are attributable to use of an indwelling urethral catheter. Catheter-acquired urinary infections (CA-UTIs) have received significantly less attention than other hospital–acquired infections, such as surgical site infections, hospital-acquired/ventilator-associated pneumonia, and bacteremia probably because CA-UTIs present apparent lower morbidity and mortality compared with the other infections, as well as limited financial impact. However, because they are common, their cumulative impact is large.

The indwelling urethral catheter is an essential tool for many hospitalized patients. It is placed for a number of reasons, including output monitoring of unstable patients, voiding management for patients with urethral obstruction, and perioperative use for selected surgical procedures. However it may carry predictable and unavoidable risk of UTI perturbing host defense mechanisms and providing easier access of uropathogens to the bladder. Fortunately, most CA-UTIs are asymptomatic and do not require antimicrobial treatment.

Asymptomatic bacteriuria is defined as culture growth of ≥105 cfu/mL of uropathogenic bacteria in the absence of symptoms compatible with UTI in a patient with indwelling urethral, indwelling suprapubic, or intermittent catheterization.

Symptomatic bacteriuria (urinary tract infection) is defined as culture growth of ≥103colony forming units (cfu)/mL of uropathogenic bacteria in the presence of symptoms or signs compatible with UTI without other identifiable source in a patient with indwelling urethral, indwelling suprapubic, or intermittent catheterization. Compatible symptoms include fever, suprapubic or costovertebral angle tenderness, and otherwise unexplained systemic symptoms such as altered mental status, hypotension, or evidence of a systemic inflammatory response syndrome.

CA-UTI may be extraluminal or intraluminal. Extraluminal infection occurs via entry of bacteria into the bladder along the biofilm that forms around the catheter in the urethra. Intraluminal infection occurs due to urinary stasis because of drainage failure, or due to contamination of the urine collection bag with subsequent ascending infection. Extraluminal is more common than intraluminal infection

The diagnosis of CA-UTI is made by the finding of bacteriuria in a catheterized patient who has signs and symptoms of UTI or systemic infection that are otherwise unexplained.

CA-UTIs are often polymicrobial and may be caused by multi-drug resistant uropathogens. Urine cultures are recommended prior to treatment to confirm that an empirical regimen provides appropriate coverage and to allow tailoring of the regimen on the basis of antimicrobial susceptibility data. Gram-negative organisms predominate in hospital-acquired urinary tract infections, almost all of which are associated with urethral catheterization. After the second day of catheterization, it is estimated that the risk of bacteriuria increases by 5 to 10% per day.

The treatment of CA-UTIs includes antibiotic therapy and catheter management.

Bacteriuria in the absence of symptoms is very common among catheterized patients. Treatment of asymptomatic bacteriuria does not affect patient outcomes and increases the likelihood of emergence of resistant bacteria. Thus, with few exceptions such as immunosuppressed patients, antibiotic treatment for asymptomatic bacteriuria in catheterized patients is not indicated. Removal of the catheter allows resolution of bacteriuria in one third to one half of cases,

Empiric antibiotic therapy for patients with CA- UTI depends on patients’clinical conditions and whether the infection has proceeded beyond the bladder (which we use to distinguish acute complicated UTI from acute uncomplicated cystitis)

Antibiotic selection for both acute complicated UTI and acute uncomplicated cystitis should take into account risk factors for resistant infection (past urine cultures, previous antibiotic therapy, health care exposures and helthcare setting resistance patterns).

Once culture and susceptibility results are available, the antimicrobial regimen should be tailored to the specific organism isolated.

The optimal duration of therapy is uncertain. Seven days is the recommended duration of antimicrobial treatment for patients with CA-UTI who have prompt resolution of symptoms, and 10–14 days of treatment is recommended for those with a delayed response. Oral therapy can be used for some or all of the treatment course if the organism is susceptible and the patient is well enough to take oral medication with adequate absorption.

Patients with CA_UTI who no longer require catheterization should have the catheter removed and receive appropriate antibiotic therapy. Patients who require extended catheterization should be managed by intermittent catheterization, if it is possible. If long term catheterization is needed and intermittent catheterization is not feasible, the catheter should be replaced at the initiation of antibiotic therapy.

The two most important strategies to prevent CA-UTI are not to use a urinary catheter and, if a catheter is necessary, to minimize the duration of use. Catheters should be inserted only when there are valid indications and removed as soon as they are no longer indicated.

Systemic antimicrobial prophylaxis should not be routinely used in patients with short-term  or long-term catheterization, including patients who undergo surgical procedures, to reduce CA-bacteriuria or CA-UTI because of concern about selection of antimicrobial resistance.

Best  practices for catheter insertion and care may delay infection acquisition and decrease risks of symptomatic infection. These include insertion techniques to minimize contamination and maintaining a closed drainage system to delay catheter colonization.

Catheter-acquired urinary tract infections must be acknowledged as an important patient safety issue, and the indwelling urethral catheter must be treated as an invasive intervention that carries a risk for patients. Attention to limiting catheter use, minimizing duration of use, and supporting optimal practices for catheter care should be implemented worldwide.