Diagnostic stewardship is defined as the process of modifying the requesting, performing, or reporting of diagnostic tests in order to improve diagnostic accuracy and patient management1. It involves requesting the right test, for the right indication, at the right time with the right interpretation of results. Diagnostic stewardship of infections promotes the appropriate use of diagnostics in order to prevent overuse of laboratory tests by unnecessary testing for non-severe, uncomplicated infections that may be treated empirically, or for non-infectious conditions that do not require antimicrobial therapy2. This minimises harms to the patient that occur from the injudicious prescription of antimicrobial therapy, such as adverse effects of drugs, antimicrobial resistance, and the risk of Clostridioides difficile-associated disease. It also facilitates the prudent use of laboratory resources.
Diagnostic stewardship comprises (1) pre-analytical (2) analytical and (3) post-analytical phases (Table 1). The Microbiology laboratory plays an important role in all three phases. Awanui labs Auckland Microbiology has recently implemented a novel pre-analytical stewardship initiative for urine culture from community patients. This involves the requirement for an appropriate symptom-based clinical indication for urine culture ordering on the electronic ordering system (e-orders).
Diagnostic Stewardship of urine culture
- Urine culture is NOT routinely required for non-pregnant adult women presenting with symptoms of uncomplicated lower UTI (simple cystitis). Instead, local and international clinical practice guidelines recommend the use of empiric narrow-spectrum short-course antimicrobial therapy based on the local antimicrobial resistance patterns of common uropathogens.3,4 At Awanui Auckland, the antimicrobial susceptibility profiles of common community pathogens are monitored periodically and the antibiograms are uploaded on our website5. Note that 99% of E. coli in the Auckland/Northland region are susceptible to nitrofurantoin, and a 5-day course of this agent would be appropriate empiric therapy for uncomplicated cystitis.
- Urine culture is also NOT recommended in the absence of symptoms and/or signs of UTI (dysuria, frequency, urgency, or suprapubic pain)3,4. Testing patients without symptoms who have a low pre-test probability of UTI will lead to low-yield tests or carry a high risk of false positivity2,6
- There are only two evidence-based indications for screening for asymptomatic bacteriuria in a patient without symptoms/ signs of UTI: these include pregnancy and screening prior to an invasive urological procedure associated with mucosal trauma (e.g. transurethral resection of prostate/bladder, ureteroscopy with lithotripsy, percutaneous stone surgery)6.
The benefits of screening for other indications are uncertain, and there is high quality evidence of adverse consequences with unnecessary antimicrobial treatment.6
eOrder for urine culture
Based on the above evidence-based recommendations, if urine culture is required, the healthcare provider is requested to mark the tick-boxes specifying one or more clinical Indications for testing on the e-order system:
- Undergoing invasive urological procedure (screen for asymptomatic bacteriuria)
- Pregnant (screen for asymptomatic bacteriuria)
- Dysuria, frequency, urgency, or suprapubic pain (symptoms of lower UTI)*
- Paediatric patient (may be associated with structural abnormalities of urinary tract, especially if recurrent)
- Male (may be associated with functional abnormalities of urinary tract, especially in older men, e.g. benign prostatic hypertrophy leading to obstructive uropathy)
- Structural or functional abnormality of urinary tract (e.g. vesicoureteral reflux, renal stones, neurogenic bladder)
- Renal transplant recipient (increased risk of complicated UTI, allograft rejection/ loss)
- Poorly controlled diabetes mellitus (increased risk of complicated UTI)
- Recurrent or persistent UTI symptoms despite empiric antimicrobial treatment
- Symptoms or signs of upper UTI/ pyelonephritis (symptoms of lower UTI plus fever, rigors, flank pain or costovertebral angle tenderness)
- Other: ____________
*Appropriate clinical indications for culture request include symptoms of lower UTI plus one or more other indications below this on list This initiative is expected to increase appropriate laboratory processing and enable correct interpretation of urine culture results, thus improving clinical outcomes2,7,8.
Table 1: Strategies in Diagnostic Stewardship of Urinary Tract Infections 2,7,8
**Urine specimens from pregnant women or patients undergoing invasive urological surgery are cultured irrespective of presence/ absence of pyuria
Dr Ranmini Kularatne
(09) 574 7399
ranmini.kularatne@awanuilabs.co.nz
References
1. Coffey KC, Morgan DJ, Claeys KC. Diagnostic stewardship: what impacts antibiotics use? Curr Opin Infect Dis. 2023;36(4):270-5.
2. Zakhour J, Haddad SF, Kerbage A, et al. Diagnostic stewardship in infectious diseases: a continuum of antimicrobial stewardship in the fight against antimicrobial resistance. Int J Antimicrob Agents. 2023;62(1):106816.
3. Community HealthPathways, Auckland Region. UTI in Adults. Available at: https://aucklandregion.communityhealthpathways.org/26703.htm
4. Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011;52(5):e103-20.
5. Awanui Labs Auckland and Northland (formerly Labtests); for Referrers. Antimicrobial Susceptibility Report: Auckland and Northland community isolates 2021. Available at: https://fl-healthscopemedia.s3.amazonaws.com/lab sites/uploads/sites/2/2022/07/Antimicrobial-susceptibility-report-Auckland-and-Northland-community-isolates-2021.pdf
6. Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2019;68(10):1611-5
7. Goebel MC, Trautner BW, Grigoryan L. The Five Ds of Outpatient Antibiotic Stewardship for Urinary Tract Infections. Clin Microbiol Rev. 2021;34(4):e0000320.
8. Claeys KC, Trautner BW, Leekha S, et al. Optimal Urine Culture Diagnostic Stewardship Practice-Results from an Expert Modified-Delphi Procedure. Clin Infect Dis. 2022;75(3):382-9.