Amount of toxin in stool correlates with C. difficile severity, study shows
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Using a new highly sensitive assay, researchers demonstrated that the amount of toxin in stool correlates with the severity of Clostridioides difficile infection, with higher concentrations associated with severe disease at diagnosis.
The highly sensitive toxin test is based on a technology called Simoa and allowed the researchers to quantify the amount of toxin in the stool of patients with suspected C. difficile infection (CDI), several of the researchers explained in a joint interview via email.
“There are many tests that can detect the C. difficile bacteria, but there is no one perfect test for determining who has true C. difficile infection,” Carolyn D. Alonso, MD, Nira R. Pollock, MD, PhD, DABMM, and Ciarán P. Kelly, MD, all of the Beth Israel Deaconess Medical Center, told Healio.
To test the assay, the researchers enrolled 615 hospitalized adults aged 18 years or older with CDI, measured their baseline stool toxin A and B concentrations, and classified them by baseline CDI severity and outcomes within 40 days.
Overall, the study showed that across all scoring systems, patients with severe baseline disease had higher stool toxin A and B concentrations than those without (P < .01), the researchers reported.
Nineteen of the patients (3.1%) had a severe outcome primarily attributed to CDI, and these patients had higher median toxin A and B than subjects in whom CDI only contributed to the outcome, subjects with severe outcome unrelated to CDI or no severe outcome (P = .003). These patients were also more likely to have detectable toxin (94.7%) than the other groups of patients (P = .02). The researchers also found that individuals with CDI recurrence had higher toxin A and B than those without (P < .001) and higher rates of detectable toxin (85.7% vs. 64%; P = .004).
Alonso, Kelly and Pollock said the findings were surprising because, although prior studies had shown a possible association between stool toxins and clinical outcomes of CDI, theirs was the first to “convincingly demonstrate” it.
“This research lays the foundation for developing a highly accurate, single-step test to better diagnose C. difficile infection and predict clinical outcomes,” they said. “Ultimately, we hope that our research will move the field toward development of a single-step test for C. difficile that can be easily deployed by clinicians without specific expertise in C. difficile diagnosis.”
In an accompanying editorial, Colleen S. Kraft, MD, MSc, and Nirja Mehta, MD, of Emory University School of Medicine, concurred, writing that the study has “excellent merit” and provides foundational knowledge for a likely “disruptive approach” to diagnosing CDI.
“Given most assays are either too sensitive or too specific or too labor intensive, this assay gets us closer to ‘just right,’” they wrote. “This work will hopefully spur commercial development of these assays.”
Reference:
Alonso CD, et al. Clin Infect Dis. 2021;doi:10.1093/cid/ciab826.
Kraft C, et al. Clin Infect Dis. 2021;doi:10.1093/cid/ciab833.