Inpatient Urine Cultures Are Frequently Performed Without Urinalysis or Microscopy: Findings From a Large Academic Medical Center

Abstract

OBJECTIVE To describe the frequency of urine cultures performed in inpatients without additional testing for pyuria DESIGN Retrospective cohort study SETTING A 1,250-bed academic tertiary referral center PATIENTS Hospitalized adults METHODS This study included urine cultures drawn on 4 medical and 2 surgical wards from 2009 to 2013 and in the medical and surgical intensive care units (ICUs) from 2012 to 2013. Patient and laboratory data were abstracted from the hospital's medical informatics database. We identified catheter-associated urinary tract infections (CAUTIs) in the ICUs by routine infection prevention surveillance. Cultures without urinalysis or urine microscopy were defined as "isolated." The primary outcome was the proportion of isolated urine cultures obtained. We used multivariable logistic regression to assess predictors of isolated cultures. RESULTS During the study period, 14,743 urine cultures were obtained (63.5 cultures per 1,000 patient days) during 11,820 patient admissions. Of these, 2,973 cultures (20.2%) were isolated cultures. Of the 61 CAUTIs identified, 31 (50.8%) were identified by an isolated culture. Predictors for having an isolated culture included male gender (adjusted odds ratio [aOR], 1.22; 95%; confidence interval [CI], 1.11-1.35], urinary catheterization (aOR, 2.15; 95% CI, 1.89-2.46), ICU admission (medical ICU aOR, 1.72; 95% CI, 1.47-2.00; surgical ICU aOR, 1.82; 95% CI, 1.51-2.19), and obtaining the urine culture ≥1 calendar day after admission (1-7 days aOR, 1.91; 95% CI. 1.71-2.12; >7 days after admission aOR, 2.81; 95% CI, 2.37-3.34). CONCLUSIONS Isolated urine cultures are common in hospitalized patients, particularly in patients with urinary catheters and those in ICUs. Interventions targeting inpatient culturing practices may improve the diagnosis of urinary tract infections. Infect Control Hosp Epidemiol 2017;38:455-460.

Effect of changing urine testing orderables and clinician order sets on inpatient urine culture testing: Analysis from a large academic medical center

“…Although we noticed a significant, but small (6.9%), decrease in the isolated urine culture and substantial decrease (75.6%) in the rate of catheterized urine cultures per 1000 patient-days, there was no significant change in the CAUTI rate post-intervention. Given that we had previously reported that isolated urine cultures were more likely to be ordered on catheterized patients and patients with prolonged hospital stays (32), we evaluated the proportion of CAUTIs associated with isolated urine cultures. We found no significant difference between study periods in the proportion of CAUTIs that were identified based on isolated urine cultures (39/125 (31.2%) pre-intervention vs. 26/125 (20.8%) post-intervention, p=0.06).…”

Best Practice Statement on Urologic Procedures and Antimicrobial Prophylaxis

“…Urine culture should not be performed without an accompanying urine microscopy due to common sample contamination as well as bacterial colonization. 24 The results should be used to direct if further testing is warranted and should be obtained prior to the selection of the AP for the procedure, thereby allowing for assessment of the likely infectious organism and its potential virulence.…”

Incidence and Diagnostic Yield of Repeat Urine Culture in Hospitalized Patients: an Opportunity for Diagnostic Stewardship

“…ICUs had the highest number of inappropriate repeat urine cultures. We previously reported that isolated urine cultures, defined as urine cultures performed without additional diagnostic testing, such as urinalysis or urine microscopy, were more likely to be ordered among ICU patients (7). Interventions targeted to ICUs and physicians with outlying ordering behavior may therefore have a great impact on reducing inappropriate repeat testing.…”

“…Due to the low numbers of straight catheterized urine cultures (0.3% of all urine cultures), these were grouped together with clean-catch urine cultures. A positive urine culture for all specimen types was defined on the basis of the established clinical breakpoints, as previously published (7,8). We defined a negative urine culture as having insignificant growth below a threshold or no growth.…”