Are We Moving Toward Diagnostic Stewardship Or Laboratory Retrogress On Clostridioides difficile Testing?

Area of Science:

• Clinical microbiology
• Infectious disease diagnostics
• Healthcare quality improvement

Background:

• Polymerase chain reaction (PCR) testing for Clostridioides difficile infection (CDI) has largely replaced enzyme immunoassays (EIA) in the U.S.
• While PCR offers higher sensitivity, concerns about overdiagnosis due to detection of asymptomatic colonization persist.
• Some institutions employ a two-step algorithm using EIA to confirm positive PCR results, aiming to mitigate overdiagnosis.

Purpose of the Study:

• To evaluate the impact of incorporating EIA testing into a PCR-exclusive system within a healthcare setting.
• To assess the sensitivity and specificity of commercial EIA platforms compared to routine PCR testing for CDI.
• To determine if EIA confirmation could improve hospital reporting and patient safety regarding healthcare-onset CDI (HO-CDI).

Main Methods:

• Comparison of routine PCR testing with two commercial EIA platforms for CDI detection.
• Analysis of PCR cycle threshold (Ct) values in relation to EIA results.
• Evaluation of the impact of electronic ordering alerts on diagnostic stewardship.

Main Results:

• EIA demonstrated less than 30% sensitivity compared to PCR, leading to an artificial reduction in reported HO-CDI cases.
• A small number of inpatients with positive EIA results, despite not meeting initial testing criteria, indicated true CDI, highlighting potential gaps in provider education.
• Lower PCR Ct values (higher bacterial load) correlated with EIA positivity, suggesting EIA's requirement for higher toxin levels for detection.

Conclusions:

• Multi-step testing algorithms using EIA may decrease HO-CDI rates but risk missing true CDI cases due to EIA's low sensitivity.
• The clinical utility of EIA in CDI management is limited.
• Enhancing provider education on appropriate CDI testing criteria is a more effective strategy to reduce unnecessary testing and improve patient care.