We're failing to make sure cultures are indicated properly in catheterized patients, which can lead to serious disruptions of care.
Catheter-associated urinary tract infections (CAUTI) represent a considerable threat for patients who require urinary catheters. It is estimated that 75% of urinary tract infections acquired during hospitalization are associated with catheterization. Moreover, the US Centers for Disease Control and Prevention (CDC) estimates that 15-25% of hospitalized patients receive catheters during their stay, underscoring that CAUTIs are truly a risk to patient safety.
Aside from reducing catheter use, a topic that has been discussed with increasing frequency is the practice of implementing culturing and stewardship. Urine cultures are part of the diagnostic surveillance for determining whether a patient has a CAUTI and the hospital is responsible for the infection, but are we haphazardly culturing?
In my experiences as an infection preventionist, I have seen urine cultures come through while wondering why they were ordered on several occasions. It’s almost second nature for some providers to order a urinalysis and/or urine culture the second a patient spikes a fever. It’s become a habitual practice that may be grounded more in comfort than true medical stewardship.
In an effort to address this underlying practice and how it often leads to unnecessary antimicrobial prescribing, a team of researchers assessed the knowledge and practices of physicians and nurses related to urine cultures of patients with catheters. The team sought to compare the Infectious Diseases Society of America (IDSA) guidelines for treating CAUTI and asymptomatic bacteriuria with how 3 hospitals within the Yale New Haven Health System were performing.
The appropriate use guidelines include a list of symptoms related to an infection of the urinary tract (dysuria, urgency, frequency after catheter removal), indications of genitourinary obstruction or trauma (hematuria, flank pain, etc.), complications related to a urologic procedure, signs of pyelonephritis, or severe shock. The IDSA guidelines note that inappropriate indications of CAUTI include a change in urine character, fever, and other non-specific symptoms like diarrhea or generalized abdominal pain. Often, this practice of pan-culturing (ordering 2 or more of the cultures for any indication, such as fever or delirium within a certain time interval and in the absence of symptom-directed evaluation) can lead not only to overdiagnosis of surveillance-based CAUTIs, but also unnecessary antimicrobial use and a delay in diagnosis of alternative issues.
The study team found that when they assessed CAUTIs within the academic health care system between October 2015 and September 2017, they could better understand the perception of urine culture necessity and results. As part of the study the team issued a survey to physicians and nurses on when they would order urine cultures within catheterized patients and what would indicate a culture was needed.
During this time, the investigators identified 184 CAUTIs; a urine culture was ordered inappropriately in 159 events (86%). In 62% of the events, the CAUTI criteria were met as a result of pan-culturing rather than the symptom-directed culturing that IDSA guidelines call for. Of these, 11% of the cases resulted in a delay in the management of other infections, including adverse drug events or infections like Clostridioides difficile, pointing out the considerable role that this pan-culturing and over-identification has in distracting from other issues. Of the 405 responses from health care workers, nurses were more likely than physicians to consider the change in urine appearance and odor as an indicator that a urine culture should be ordered among catheterized patients. A majority of the physicians and nurses surveyed were unable to accurately identify indications for ordering cultures.
The presence of microorganisms in the urine culture of a catheterized patient triggers treatment, often without a conversation regarding the high incidence of colonization and contamination of urine samples among this patient population. This, coupled with the gaps in provider knowledge, should be seen as a stark reminder as to why we need to follow IDSA guidelines and practice better diagnostic stewardship. Ultimately, ordering urine cultures in catheterized patients based off subjective findings can lead to unnecessary antimicrobial use and/or delays in care surrounding other issues.