Diagnostic stewardship of urine cultures

Background

• Asymptomatic bacteriuria is common, but positive urine cultures are still often inappropriately treated
• The process of inappropriately treating asymptomatic bacteriuria can be interrupted at the culture collection stage

Interventions

Urine Culture Ordering

• The following practices are recommended:
  • Require documentation of signs or symptoms of UTI to obtain a urine culture, including dysuria or flank pain
    • Patients without urinary catheters
      • Appropriate signs and symptoms include dysuria, suprapubic pain, flank pain, CVA tenderness, or septic shock
      • Signs and symptoms of uncertain appropriateness include fever or leukocytosis with unknown cause
      • Inappropriate signs and symptoms include altered mental status or change in urine characteristics
    • Patients with urinary catheters are as above, except that delirium is of uncertain appropriateness
  • Replace stand-alone urine culture orders with conditional reflex urine cultures
    • Direct urine culture may still need to be available to urology and obstetrics
    • Criteria for reflex culture is not standardized; elevated WBC count ≥10-50 is appropriate, but unclear whether leukocyte esterase or urine nitrate was appropriate
  • Implement best practice alerts to discourage ordering urine cultures in the abscence of signs or symptoms of UTI
  • Automatically cancel repeat urine cultures within 5 days of a positive culture (during the same hospital admission and 7 days for long-term care residents)
• As well, urine cultures should not be included in any standardized order sets except for septic shock
• Urine cultures should not be collected in response to a change in urine characteristics

Processing Urine Culture

• The following practices are recommended:
  • Use elevated urine WBC as a criterion to reflex process a urine culture when the clinician orders a urine culture
    • See section above for further detail
  • Require documentation of collection site and method (e.g. clean catch) prior to processing urine culture
• Reflex urine cultures should not be done on a urinalysis where the clinician did not specifically request culture

Urine Culture Reporting

• The following practices are recommended:
  • Report that even high colony counts may not represent true infection in the absence of signs or symptoms
  • Nudge clinicians to not treat asymptomatic bacteriuria or mixed flora
  • Differentiate typical uropathogens from contaminants
  • Without urine culture results when there are more than 2 unique bacterial strains in culture
  • Report only recommended antibiotics if the organism is susceptible
  • Withhold fluoroquinolone susceptibilities unless there is resistance to preferred oral antibiotics
• The reports should not nudge clinicians to not treat based on low colony counts, either
• Reports should not withhold information about organism identification or antibiotics susceptibilities unless the clinician calls the microbiology lab

Further Reading

• Optimal Urine Culture Diagnostic Stewardship Practice—Results from an Expert Modified-Delphi Procedure. Clin Infect Dis. 2022;75(3):382-9. doi: 10.1093/cid/ciab987