Impact of Multiplex Testing on the Identification of Pediatric Clostridiodes Difficile

Objectives: To evaluate whether the implementation of a multiplex gastrointestinal pathogen panel (GIP) was associated with changes in Clostridioides difficile (C difficile) testing and detection rates.

Study design: We conducted an observational study using interrupted time series analysis and included pediatric patients with testing capable of detecting C difficile. From 2013 to 2015 ("conventional diagnostic era"), stool testing included C difficile-selective polymerase chain reaction and other pathogen-specific tests. From 2015 to 2017 ("GIP era"), C difficile polymerase chain reaction was available along with the GIP, which detected 22 pathogens including C difficile, and replaced the need for additional tests. Outcomes included C difficile testing and detection rates in ambulatory, emergency department, and inpatient settings.

Results: There were 6841 tests performed and 1214 C difficile positive results. Across the 3 settings, GIP era had significantly higher C difficile testing (1.7-2.3 times higher) and C difficile detection rates (1.9-3.4 times higher) compared with conventional diagnostic era. After adjusting for the number of tests performed, detection rates were no longer significantly different. Of C difficile positive GIPs, 31% were coinfected with another organism. With GIP testing, patients 1 year of age had a significantly higher C difficile percent positivity than 2-year-old (P = .02) and 3- to 18-year-old children (P < .01). Younger children with C difficile were more likely to be coinfected (P < .01).

Conclusions: Introducing a multiplex panel led to increased C difficile testing, which resulted in increased C difficile detection rates and potential identification and treatment of colonized patients. This highlights an important target for diagnostic stewardship and the challenges associated with multiplex testing.