QAPI 112 - Implementation of a Two-step Testing Method for Clostridioides Difficile Reduces Infection Rate, Treatment, and Isolation

Background: Laboratory-identified (LabID) cases of Clostridrioides difficile infection (CDI) are a publicly reported metric to the National Healthcare Safety Network (NHSN). Diagnosing CDI by polymerase chain reaction (PCR) does not allow for identification of C. difficile colonization, resulting in overdiagnosis, overtreatment, unnecessary isolation, and an increased reported CDI rate. A two-step testing method for CDI diagnosis first uses PCR to identify the C. difficile gene followed by enzyme immunoassay (EIA) to detect the toxic protein responsible for causing CDI, thereby differentiating active CDI from colonization.

Methods: Plan-Do-Study-Act design was used to analyze the effects of implementing a two-step testing method for diagnosing CDI at an inpatient rehabilitation facility between May 2021 and February 2022. Upon implementation, clinical staff received education on interpretation of results. C. difficile results were reviewed to determine CDI (PCR positive and EIA positive) versus colonization (PCR positive and EIA negative). Compliance with treatment and isolation policies were tracked. Interdisciplinary reviews assessed for delayed or misdiagnosis for complicated cases of CDI. Standardized infection ratio (SIR) was calculated using NHSN analytics tools.

Results: Policies were updated to provide clinical staff with resources explaining the two-step testing method and result interpretation. Nineteen cases of CDI and 11 cases of colonization were identified. The SIR for this time period was 0.464, reduced from 0.742 if the two-step testing method had not been implemented. This resulted in a 37.5% decrease in publicly reported SIR. Of the C. difficile cases identified as colonization, 64% were compliant with the isolation policy and 55% were compliant with treatment recommendations.

Conclusions: Using a two-step testing method to diagnose CDI reduces the overall number of CDI cases and publicly reported SIR. This method also reduces the need for patient isolation for CDI and treatment for cases of colonization.