Background:
The Microbiology Division will change the criteria used to reflex urines to a urine culture “if indicated”. In the future, urine will only be reflexed to a urine culture if white blood cells (WBC) are ≥ 10/high power field (hpf). There is no universally accepted standard. However, several recent studies have concluded a 10 WBC/hpf cutoff provides better clinical relevance than our current criteria.1-6
The goal is to increase the specificity of the culture reflex criteria and subsequently decrease the number of patients with asymptomatic bacteriuria who may be unnecessarily treated with antibiotics.
The following table contrasts the current and revised criteria used to reflex to a urine culture:
UA Parameters
|
Current Reflex Criteria
(any of the following:)
|
Revised Reflex Criteria
|
WBC/hpf
|
>5
|
> 10
|
Nitrite
|
Positive
|
Not considered
|
Leukocyte esterase
|
Positive
|
Not considered
|
Effective date: April 18, 2022
Test Code: UAWC
Important considerations when ordering “urinalysis with reflex culture” vs “urine culture”:
- Indications for “urinalysis with reflex culture” include: non-specific/atypical symptoms (such as fever, malaise, mental status changes, abdominal pain without other cause).
- Indications for “urine culture” include: symptoms suggestive of possible urinary tract infection (e.g. frequency, urgency and dysuria), complicated cystitis, pyelonephritis, high risk patients (example: asymptomatic pregnant women, pre-urologic surgical patients), pediatric patients.
Specimen Required for Urinalysis with Reflex to Urine Culture:
15.0 mL screw-capped sterile container
OR
4.0 mL urine in a gray top BD Vacutainer® Urine C&S tube and
8.0 mL urine in red/yellow top BD Vacutainer® UA Preservative tube and
6.0 mL urine in a red top BD Vacutainer® no additive tube
Stability:
Ambient:
2 hours: screw-capped sterile container & BD Vacutainer® no additive tube
72 hours: BD Vacutainer® UA Preservative tube
48 hours: BD Vacutainer® Urine C&S tube
Refrigerated:
24 hours: screw-capped sterile container & BD Vacutainer® no additive tube
Frozen: Unacceptable
Turnaround time (TAT):
Urinalysis with Reflex Culture:
STAT 60 minutes
Routine 2-4 hours
Culture, Urine (bacteria):
Routine 1-3 days
Rejection criteria: Specimens that exceed stated stability, unlabeled/mislabeled/mismatched specimens, specimens submitted in leaking containers.
A summary of all tests offered by our laboratory services can be found here: http://www.pathology.uci.edu/services/index.asp
Cassiana Bittencourt, MD
Director
Division of Clinical Microbiology
Lauri D. Thrupp, MD
Professor of Medicine Emeritus
Senior Hospital Epidemiologist, Consultant Clinical Microbiology Laboratory
Edwin S. Monuki, MD, PhD
Chair
Department of Pathology & Laboratory Medicine
References
- Xiao et al. Urine Reflex Testing: Why and How? Clinical Laboratory News. SEP.1.2021. https://www.aacc.org/cln/articles/2021/september/urine-reflex-testing-why-and-how.
- Lynch et al. Effect of urine reflex culturing on rates of cultures and infections in acute and longterm care. Antimicrob Resist Infect Control . 2020 Jun 29;9(1):96. doi: 10.1186/s13756-020-00762-1.
- Watson et al. Using clinical decision support to improve urine culture diagnostic stewardship, antimicrobial stewardship, and financial cost: A multicenter experience. Infect Control Hosp Epidemiol . 2020 May;41(5):564-570. doi: 10.1017/ice.2020.37.
- Richards et al. Reflex urine culture testing in an ambulatory urology clinic: Implications for antibiotic stewardship in urology. Int J Urol. 2019 Jan;26(1):69-74. doi: 10.1111/iju.13803.
- Humphries et al. Point-Counterpoint: Reflex Cultures Reduce Laboratory Workload and Improve Antimicrobial Stewardship in Patients Suspected of Having Urinary Tract Infections. J Clin Microbiol. 2016 Feb;54(2):254-8. doi: 10.1128/JCM.03021-15.
- Doern et al. Diagnosis of Urinary Tract Infections in Children. J Clin Microbiol. 2016 Sep;54(9):2233- 42.
- Nicolle et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clinical Infectious Diseases, Volume 68, Issue 10, 15 May 2019, Pages e83–e110.
- Cumitech 2C: Laboratory Diagnosis of Urinary Tract Infections. ASM Press.2009
- Leber et al. Clinical Microbiology Procedures Handbook. 4th Edition. ASM Press. 2016
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