Beyond the bugs: why toxin detection is key in two-tiered C. diff tests

Area of Science:

• Infectious Diseases
• Microbiology
• Clinical Diagnostics

Background:

• Clostridioides difficile (C. diff) infection is a significant healthcare concern.
• Distinguishing active infection from colonization is crucial for appropriate treatment.
• Current diagnostic methods may not always differentiate between infection and colonization.

Purpose of the Study:

• To evaluate a two-tier diagnostic algorithm combining C. diff toxin assay with polymerase chain reaction (PCR).
• To determine if this approach improves patient outcomes and antibiotic stewardship.
• To assess the clinical characteristics and outcomes of toxin-positive versus toxin-negative patients.

Main Methods:

• Retrospective chart review of inpatients positive for C. diff by PCR.
• Implementation of a two-tier testing algorithm (PCR followed by toxin assay).
• Analysis of patient demographics, clinical features, outcomes, and antibiotic initiation.

Main Results:

• Toxin-positive patients exhibited more severe colitis symptoms, higher white blood cell counts, and increased fatality rates.
• Antibiotic prescription was significantly higher in toxin-positive patients (98%) compared to toxin-negative patients (56%).
• A notable percentage of toxin-negative patients (44%) did not receive antibiotics.

Conclusions:

• The two-tier testing strategy effectively identifies active C. diff infections, aiding antibiotic stewardship.
• This approach helps differentiate infection from colonization.
• Clinical judgment is still necessary for managing toxin-negative patients with colitis symptoms.