A recent study assessed the impact of implementing multistep diagnostic testing for Clostridioides difficile infection (CDI) in an academic hospital system, specifically using reflex testing with the C. DIFF QUIK CHEK COMPLETE enzyme immunoassay. Results showed a significant decrease in hospital-onset CDI (HO-CDI) rates, from 0.352 to 0.115 cases per 1,000 patient-days post-reflex testing. Though the use of CDI-targeted antibiotics also decreased, it did not match the drop in CDI rates, suggesting room for optimizing treatment strategies.
Analysis of PCR cycle threshold (Ct) values revealed that PCR-positive samples that were GDH and toxin positive had significantly lower Ct values compared to those that were GDH positive but toxin negative. This suggests a potential difference in infection severity or bacterial load. A Ct value of 28.65 was identified as a distinguishing cut-off between these two groups. However, 54% of toxin-negative samples still had Ct values below this threshold, indicating possible CDI despite a negative toxin test. Reflex testing effectively reduced CDI rates, but further research is needed to improve differentiation between CDI and C. difficile colonization in discordant cases.
Reference: Hilt EE, Vaughn BP, Galdys AL, et al. Impact of the Reverse 2-Step Algorithm for Clostridioides difficile Testing in the Microbiology Laboratory on Hospitalized Patients. Open Forum Infect Dis. 2024 Apr 27;11(5):ofae244. doi: 10.1093/ofid/ofae244. PMID: 38756762; PMCID: PMC11097206.
