Two-Step Testing Linked With Lower Rate of CDI Treatment in Colonized Patients

Switching from polymerase chain reaction (PCR) testing to two-step algorithm testing correlated with lower rates of treatment for Clostridioides difficile infection (CDI), according to a study published in Clinical Microbiology and Infection.

“Diagnosis of CDI can be challenging due to high colonization rates. Unlike PCR-only testing, two-step algorithm testing (that includes toxin and PCR) may help differentiate colonization from active infection,” wrote corresponding author Lana Dbeibo, MD, MPH, of Indiana University Health, Indianapolis, Indiana, and study coauthors. 

The retrospective study analyzed data for patients with positive C difficile testing results at a single institution over 2 years. The first year of the analysis featured PCR-only testing, and positive results were displayed in the electronic medical record as “positive.” The second year featured two-step testing, and positive results were either displayed as “likely colonized” or “toxin positive.”

Among 354 patients who tested positive in the PCR-only period, 93% received CDI-specific treatment, according to the study. During the two-step testing period, 142 patients tested as likely colonized, and 42% of them received treatment. Another 114 tested toxin-positive, and 100% of them received treatment.

During the two-step testing era, patients with PCR positive or likely colonized test results were less likely to be treated for CDI, multivariate analysis showed.

“We demonstrate that switching from a highly sensitive PCR test to a two-step test is associated with lower rates of treatment with C difficile–specific antibiotic therapy,” researchers wrote. “This difference was related to lower treatment rates in those whose tests resulted as ‘likely colonized’ without increasing rates of intensive care unit transfers.”

Reference

Dbeibo L, Lucky CW, Fadel WF, et al. Two-step algorithm-based Clostridioides difficile testing as a tool for antibiotic stewardship. Clin Microbiol Infect. 2023;29(6):798.e1-798.e4. doi: 10.1016/j.cmi.2023.02.008