Growth of S. aureus in the urine should prompt further investigation with blood cultures to explore the possibility of hematogenous dissemination to the urinary tract. Organisms leading to bacteremia due to CA-UTI are most commonly gram-negative bacilli (E. coli, Klebsiella species, Pseudomonas aeruginosa) and E. faecalis.21
What is the difference between CA-ASB and CA-UTI?
CA-ASB is defined as the presence of ≥ 1 bacteria species growing on urine culture at ≥ 100,000 cfu/mL in a patient with a history of urinary catheterization and/or indwelling UC who lacks signs or symptoms of UTI. In a man with a condom catheter, CA-ASB is defined using the same criteria, but the urine sample is collected after a fresh condom catheter is applied.5 The difference between CA-ASB and CA-UTI is simply the presence or absence of signs and symptoms related to UTI. Currently, there is no standard definition for significant bacteriuria in a catheterized patient.5 Pyuria found on urinalysis is indicative of genitourinary inflammation and can be present in both CA-ASB and CA-UTI. The absence, presence, and/or degree of pyuria in catheterized patients does not accurately differentiate between CA-ASB and CA-UTI.5,22,23 On the other hand, the absence of pyuria in a symptomatic catheterized patient suggests an etiology other than CA-UTI.5
How can CA-UTI be prevented in patients with a short-term indwelling urinary catheter?
If a short-term UC is essential, the most important approach to preventing CA-UTI is limiting the duration of time it will be used. Strategies such as computer-based order entry and care maps with automated discontinuation of UCs have been shown to decrease catheter usage.19 Using closed-systems for UC collection with ports in the distal catheter for needle aspiration of urine has also been shown to decrease the incidence of CA-UTI.5 Securing the UC to avoid urethral trauma, aseptic techniques for insertion and repositioning, and placement of the tubing and collection bag below the level of the bladder to prevent reflux will likely also prevent CA-UTI, but these strategies have not been evaluated thoroughly.19
When should you screen for and treat CA-ASB?
The 2009 Infectious Diseases Society of America (IDSA) guidelines recommend that the only patients who should be screened and treated for CA-ASB are pregnant women and those who will undergo a potentially traumatic urologic procedure for which mucosal breaching may occur, causing bleeding. Routinely screening or treating patients for CA-ASB in not recommended in any other group of patients and will lead to unnecessary antibiotic use and antibiotic resistance.5
UTI Associated with Percutaneous Nephrostomy and Ureteral Stenting
Similar systemic symptoms of infection (fever, rigors, malaise, shock) are present in patients with and without percutaneous nephrostomy (PCN) and/or ureteral stent placement. Dysuria is not commonly present in those with PCN. The first signs of CA-UTI may be decreased urine output and pericatheter leakage due to an obstructive process resulting from the encrustation.24-27 The most common complaint among patients with either acute or chronic ureteral stenting is discomfort, which has been described as “urinary symptoms” and “body pain.”28 This discomfort can be related to ureteral hyperperistalsis after placement of the stent and is usually self-limiting. Ureteral stent migration, usually at the distal end, can also lead to discomfort, but is easily rectified with cystoscopy.25 Body pain and/or urinary symptoms in the setting of ureteral stenting are not indicative of infection alone.
