What is Diagnostic Stewardship?

In the field of infection prevention and control (IPC), diagnostic stewardship is emerging as a critical strategy for reducing healthcare-associated infections (HAIs) and combating antimicrobial resistance. While antimicrobial stewardship focuses on the appropriate use of antibiotics, diagnostic stewardship ensures that the right tests are ordered, performed correctly, and interpreted accurately—preventing misdiagnosis, overdiagnosis, and unnecessary antibiotic use.

What is Diagnostic Stewardship?

Diagnostic stewardship involves the thoughtful selection, collection, processing, and interpretation of diagnostic tests. It aims to:

• Ensure clinically appropriate testing to avoid overuse or underuse.
• Prevent false positives or false negatives that can lead to mismanagement.
• Minimize unnecessary antibiotic prescriptions, reducing antimicrobial resistance risks.
• Improve the accuracy of HAI surveillance data by avoiding false HAI diagnoses.

In essence, diagnostic stewardship enhances the reliability and clinical utility of diagnostic tests, leading to better patient outcomes and more effective infection control.

Why Does Diagnostic Stewardship Matter in Infection Control?

Inappropriate diagnostic testing can result in incorrect HAI diagnoses, unnecessary treatments, and the overuse of isolation precautions—all of which strain healthcare resources. Examples include:

• Overtesting: Frequent or indiscriminate use of diagnostic tests (e.g., urine cultures) can lead to false positives, triggering unnecessary antibiotic treatments. INEQUALITIES/DISPARITIES ISSUE
• Undertesting: Failure to order appropriate tests (e.g., delayed blood cultures) can result in missed or delayed diagnoses, leading to untreated infections.
• Misinterpretation: Diagnostic errors or contamination of specimens can create confusion, prompting unnecessary infection control measures or inappropriate treatments.

Effective diagnostic stewardship helps healthcare teams distinguish true infections from colonization or contamination, enabling more precise infection prevention efforts.

Examples of Diagnostic Stewardship in IPC

1. Improving Blood Culture Practices to Prevent False Positives

Blood cultures are essential for diagnosing bloodstream infections, but when performed incorrectly, they can yield false positives due to skin flora contamination. This can lead to inappropriate antibiotic use and unnecessary infection precautions.

• Diagnostic stewardship strategies:
  • Using dedicated phlebotomy teams trained in proper aseptic technique.
  • Implementing blood culture diversion devices to reduce contamination.
  • Limiting the number of blood cultures to avoid overtesting.
• Impact: Reducing false positives lowers unnecessary antibiotic exposure and prevents the mislabeling of patients with HAIs.

2. Urine Culture Stewardship to Reduce CAUTI Misdiagnosis

Catheter-associated urinary tract infections (CAUTIs) are common HAIs, but overtesting leads to frequent false-positive results due to asymptomatic bacteriuria (ASB). Treating ASB with antibiotics increases resistance risks without clinical benefit.

• Diagnostic stewardship strategies:
  • Using symptom-based urine testing algorithms to prevent unnecessary cultures.
  • Restricting automatic urine cultures for catheterized patients unless clinically indicated.
  • Implementing reflex testing protocols where only positive urinalysis results trigger urine cultures.
• Impact: Reducing unnecessary urine cultures prevents overdiagnosis of CAUTIs and inappropriate antibiotic treatment.

3. Molecular Testing for C. difficile: Balancing Sensitivity with Accuracy

Molecular tests for Clostridioides difficile (C. diff) are highly sensitive but can detect colonization rather than true infection. Overdiagnosis can lead to unnecessary isolation precautions and treatment.

• Diagnostic stewardship strategies:
  • Implementing two-step testing algorithms (e.g., GDH/EIA followed by PCR for positives) to improve diagnostic accuracy.
  • Using clinical criteria (e.g., symptoms + risk factors) to guide test ordering.
• Impact: Reducing false positives ensures that only patients with true C. diff infections receive targeted treatment and infection control measures.

Effective diagnostic stewardship directly contributes to infection prevention and control by:

• Reducing HAIs: Accurate diagnoses prevent mislabeling of patients as HAI cases, improving the validity of infection surveillance data.
• Minimizing antibiotic overuse: Avoiding false-positive results prevents unnecessary antibiotic prescriptions, slowing antimicrobial resistance.
• Improving patient safety: Accurate diagnoses ensure appropriate treatment and infection control measures.
• Optimizing resource use: Reducing unnecessary testing conserves laboratory and infection control resources.

Key Takeaway: Precision in Diagnosis, Precision in Prevention

Diagnostic stewardship is a powerful yet often underutilized tool in infection prevention and control. By optimizing diagnostic testing practices, hospitals can reduce the overdiagnosis of HAIs, promote responsible antibiotic use, and enhance patient safety. For IPC teams, implementing diagnostic stewardship strategies is essential for achieving more accurate HAI surveillance, better antimicrobial stewardship, and improved overall infection prevention outcomes.