Two-step testing for Clostridioides difficile appears safe in multicenter study
Using an enzyme immunoassay after a positive nucleic acid amplification test was associated with a decrease in hospital-onset Clostridioides difficile infections and a reduction in related antibiotic use but no change in emergent colectomies.
Two-step testing for Clostridioides difficile infection (CDI) was associated with a decrease in hospital-onset CDI and a reduction in antibiotic use with no change in emergent colectomy rates, a study found.
This longitudinal cohort study included 2,657,324 patient-days across eight U.S. hospitals from July 2017 through March 2022 to look at the impact of implementing a two-step laboratory test method for C. difficile: a nucleic acid amplification test (NAAT) followed by an enzyme immunoassay (EIA) for presence of toxin in stool of positive specimens. The effects were assessed by time-series analysis with generalized estimating equation regression models. Each hospital had a year's worth of data from before and after the testing system was implemented. Results were published by Clinical Infectious Diseases on June 6.
On the primary outcome of reported incidence of hospital-onset CDI, two-step testing was associated with a significant decrease (incidence rate ratio [RR], 0.53 [95% CI, 0.48 to 0.60]; P<0.001). Utilization of oral vancomycin and fidaxomicin also dropped significantly (RR, 0.63 [95% CI, 0.58 to 0.70]; P<0.001). On the outcome of emergent colectomy, there were no significant changes in level (RR, 1.16 [95% CI, 0.93 to 1.43]; P=0.18) or trend (RR, 0.85 [95% CI, 0.52 to 1.39]; P=0.51).
The study authors concluded that the new testing system was associated with a decline in diagnosis of hospital-onset CDI. “In this case, the decline is likely attributable to the higher specificity of two-step testing—though participating hospitals may also have had active antibiotic stewardship and infection prevention efforts operating in parallel,” they said. The authors added that the findings on antibiotic use and colectomy rates provide indirect reassurance that the intervention did not result in underdiagnosis of CDI requiring medical treatment or fulminant CDI requiring surgery, respectively.
“There are two concerns in the debate, both linked to treatment; over-treatment of colonized patients who do not require treatment, and under-treatment of CDI patients who may incur clinical deterioration from lack of treatment,” an accompanying editorial observed. The editorial said that emergent colectomies are not an effective measure of complications of untreated CDI and noted that a further complicating issue is the variation in treatment of patients with positive NAAT and negative EIA results. “Controlled trials are needed,” the editorialist said.