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Pyuria is defined as >10 WBC per high powered field (HPF) without a urinary catheter, or >25 WBC/HPF with a catheter. Bacteriuria is the presence of more than 10^5 or 100,000 colony forming units (CFU) of bacteria in the urine. This can be divided into symptomatic or asymptomatic. Potential symptoms are broad and include genitourinary-specific symptoms like flank pain, hematuria, dysuria, urinary frequency or urgency, suprapubic pain, flank pain or costovertebral tenderness, or sensation of bladder distention, or could be systemic or non-specific like delirium, altered mental status, fever or rigors (IDSA 2009). Note that cloudy or malodorous urine are not suggestive symptoms of UTI. It is also important to rule out other causes of these potential symptoms, e.g. dehydration, medications, or another infection, before attributing them to the catheter.
A urinary tract infection (UTI) is defined by the presence of UTI-suggestive symptoms along with bacteriuria with no other identified source. A catheter associated urinary tract infection (CAUTI) is defined as a UTI in a patient with an indwelling urethral, indwelling suprapubic, condom, or intermittent catheterization within 24 hours of catheter insertion and for 24 hours after removal of the catheter (IDSA 2009). While the guidelines do not specifically address female external catheters, Dr. Woc-Colburn identifies that the device can cause microabrasions and proximity to the perineum or anus can also foster colonization.
Dr. Woc-Colburn points out that CAUTIs are rarely associated with dysuria. In a study involving 1,497 newly catheterized patients, there were 235 new cases of nosocomial CAUTI, and more than 90% of the infected patients were asymptomatic (Tambyah 2000). Therefore it is important to differentiate from the discomfort associated with catheter insertion from the discomfort associated with UTI. Dr. Woc-Colburn points out that following the catheter insertion bundle, e.g. using a lubricating gel when inserting the foley into the urethra, can help minimize discomfort and subsequent confusion.
Risk factors for CAUTI include duration of catheter, female sex, manipulation of the catheter, older age, diabetes and elevated serum creatinine at the time of insertion (IDSA 2009). Dr. Woc-Colburn reminds us urinary catheters are a “third leg” and the subsequent immobility increases risk of subsequent complications for the patient.
The IDSA CAUTI guidelines are a bit dated as they were last published in 2009, but they recommend 7 day duration for patients who have prompt resolution of signs and symptoms, with extension to 10-14 days if delayed response or if the catheter must stay in place.
Antibiotic choice should be dictated by your local antibiogram, but common first-line agents are ceftriaxone or levofloxacin. Then narrow antibiotics based on culture susceptibilities. There is insufficient evidence for other fluoroquinolones. A 5-day course can be considered in patients with CAUTI who are not severely ill, and a 3-day antimicrobial regimen without upper urinary tract symptoms (e.g. pyelonephritis) (IDSA 2009). Day one is the day that you exchange the catheter (i.e. achieve source control) and start antibiotic therapy.
When a urine culture results with multiple bacteria and/or candida, Dr. Woc-Colburn recommends a few quality control steps before interpreting the results. First, she suggests the sample comes from a fresh catheter (i.e. not one that has been in place for days or weeks), and to not pull the sample from the collection bag. Second, she insists on ensuring the catheter device hasn’t been contaminated by patient stool. Both of these measures solidify that you are capturing the status of the infection in the bladder and not a catheter biofilm or nearby contamination.
After replacing the catheter and ensuring there is no stool contamination, she then suggests you repeat the urinalysis as well as urine culture. If the patient has evidence of clinical deterioration or sepsis, you should cover with broad-spectrum antibiotics and narrow later. If the patient is stable, she urges us to consider the following possibilities: Consider whether the patient has kidney stones as a source of bacteria and discuss with your local infectious disease consultant about the possibility of colonization.
Based on IDSA Guidelines (IDSA 2009):
Other considerations for catheters may include (not guideline based):
In patients who will be briefly immobilized during their hospitalization, such as an orthopedic surgery patient, a urinary catheter is often considered. Dr. Woc-Colburn encourages intermittent catheterization by the patient if they are able, over placing a urinary catheter. If the patient requires surgery, the catheter can usually be removed within 24 hours post-op, or once the anesthesia has resolved and the patient isn’t having any urinary retention from medications or pain. Consider bladder stimulants as adjuncts to facilitating catheter removal.
In patients with chronic immobilization, such as secondary to a neurologic disorder, chronic catheterization may be necessary, but Dr. Woc-Colburn urges attempting intermittent catheterization when able.
Dr. Woc-Colburn cites a recent intervention that reduced overtreatment of asymptomatic bacteriuria (ASB) compared with standard quality improvement methods. These improvements persisted during a low-intensity maintenance period and were more pronounced in long-term care (Trautner 2015).
Dr Woc-Colburn’s take-home points are:
Listeners will challenge the convention that pyuria or bacteriuria in urinary catheters is a pathologic state that always requires treatment.
After listening to this episode listeners will…
Dr. Woc-Colburn reports no relevant financial disclosures, and the following non-relevant disclosures: Honoraria from IDSA and ASTMH. The Curbsiders report no relevant financial disclosures.
Maleque N, Coleman C, Evans S, Woc-Colburn L, Amin M, Trubitt M. “### Don’t Get Caught With a CAUTI”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast Final publishing date July 3 2023.
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Producer and Writer:: Noble Maleque MD
Show Notes: Caroline Coleman MD & Noble Maleque MD
Cover Art and Infographic: Caroline Coleoman MD & Sean Evans MD
Hosts: Monee Amin MD & Meredith Trubitt MD
Reviewer: Sai S Achi, MD MBA
Showrunners: Matthew Watto MD, FACP; Paul Williams MD, FACP
Technical Production: PodPaste
Guest: Laila Woc-Colburn MD
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