Urinary tract infections (UTI) associated with urinary catheters
Catheter-associated urinary tract infections (UTIs) are a common healthcare-associated infection. Bacteriuria in patients with indwelling bladder catheters occurs at a rate of approximately 3 to 10 percent per day of catheterization. Of those with bacteriuria, approximately 10 to 25 percent develop UTI. The most important risk factor is the duration of catheterization. Other risk factors include errors in catheter care.
●Fever is the most common symptom of catheter-associated UTI. Pyuria is usually present. Localizing symptoms may include flank or suprapubic discomfort, costovertebral angle tenderness, and catheter obstruction. Nonspecific findings include new-onset delirium or other systemic manifestations that suggest the possibility of infection. However, these symptoms are not specific to UTI and may be seen in catheterized patients without bacteriuria. Pyuria is also common in catheterized patients with bacteriuria without UTI.
●The diagnosis of a catheter-associated UTI is made by the finding of bacteriuria in a catheterized patient who has signs and symptoms that are consistent with UTI or systemic infection and are otherwise unexplained. Consistent findings may be specific to the urinary tract or may be more general, such as fever, leukocytosis, malaise, or signs of sepsis. If the diagnosis is based on such nonspecific findings, the evaluation should rule out the possibility of other systemic infections (eg, bacteremia, pneumonia, skin or soft tissue infection) prior to attributing them to a catheter-associated UTI.
●Ideally, urine samples for culture should be obtained by removing the indwelling catheter and obtaining a midstream specimen or, if ongoing catheterization is warranted, a specimen through a new catheter. When this is not possible, the culture should be obtained through the catheter port, not the drainage bag.
●Antimicrobial selection should be based upon the culture results when available. However, in some cases, prompt treatment is warranted prior to the availability of culture data. In such cases, empiric antimicrobial choice should be tailored to results of past cultures, use of prior antimicrobial therapy, community prevalence of antimicrobial resistance, and antimicrobial allergies of the patient. Urine Gram stain, if available, can also guide empiric antimicrobial choice. Depending on the clinical response, the infecting organism, and the agent used for treatment, 7 to 14 days of therapy is generally appropriate.
●In general, patients with infection who no longer require catheterization should have the catheter removed and receive appropriate antimicrobial therapy. Patients who require extended catheterization should be managed with intermittent catheterization, if possible. If long term catheterization is needed and intermittent catheterization is not feasible, the catheter should be replaced at the initiation of antimicrobial therapy.
●Evaluating for asymptomatic bacteriuria in patients with indwelling catheters is warranted only in the setting of pregnancy or prior to urologic procedures for which mucosal bleeding is anticipated. For other asymptomatic patients with indwelling catheters, routine urine cultures and urinalyses are not warranted and treatment of incidentally discovered asymptomatic bacteriuria is not indicated.
●Avoidance of unnecessary catheterization, use of sterile technique for insertion, and removal as soon as possible are essential to the prevention of catheter-associated UTI. Antimicrobial agents have no role in prevention of infection for the majority of patients with urinary catheters.
Antimicrobial therapy of catheter-associated UTI is similar to that for acute complicated cystitis. This is discussed in detail elsewhere.
Antimicrobial selection should be based upon the culture results when available. However, in some cases (eg, in septic or otherwise seriously ill patients, in the presence of major comorbidities) prompt treatment is warranted prior to the availability of culture data. In such cases, empiric antimicrobial choice should be tailored to results of past cultures, use of prior antimicrobial therapy, community prevalence of antimicrobial resistance, and antimicrobial allergies of the patient. Urine Gram stain, if available, can also guide empiric antimicrobial choice. If not available, empiric therapy should provide coverage against gram-negative bacilli.
If the patient is not seriously ill, and one does not suspect multi-drug resistance, gram-negative bacilli may be treated empirically with a third-generation cephalosporin (eg, ceftriaxone 1 g IV once daily or cefotaxime 1 g IV every eight hours) or a fluoroquinolone (eg, ciprofloxacin at 500 mg PO or 400 mg intravenously twice a day or levofloxacin 250 to 500 mg PO or IV once daily). If the patient is more seriously ill or if presence of multi-drug resistance is suspected (eg, any patient in the ICU or a patient who has been in the hospital for several days), then broader spectrum empiric regimens should be used. As an example, if Pseudomonas aeruginosa is suspected, treatment with ciprofloxacin, ceftazidime (1 g IV every eight hours) or cefepime (1 g IV every 12 hours) may be administered. If an extended-spectrum beta-lactamase (ESBL) producing organism is suspected (usually based on prior cultures), treatment options are generally limited to a carbapenem.
Gram positive cocci on urine Gram stain may represent enterococci or staphylococci; empiric management with vancomycin is generally appropriate pending further susceptibility data.
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. Depending on the clinical response, the infecting organism, and the agent used for treatment, 7 to 14 days of therapy is generally appropriate (with use of the longer end of this range for patients who respond slowly)．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.