PCR Cycle Threshold–Guided Management of Pediatric Clostridioides difficile Infections

This follow-up study expands on our previous work demonstrating that a PCR cycle threshold (Ct)-guided diagnostic approach improves the management of pediatric <i>Clostridioides difficile</i> infection (CDI) and reduces unnecessary treatment of colonized children. We evaluated the performance of the Gastroenteritis PCR Panel by QIAstat-Dx as a standalone method in combination with the PCR cycle threshold (Ct) value in PCR-positive samples to predict the presence of free toxins. In addition, we evaluated the impact of reporting toxin production results based on PCR Ct value alongside a comment in our electronic medical record. The QIAstat-Dx assay achieved 100% sensitivity and negative predictive value (NPV), with a specificity of 69% and a positive predictive value (PPV) of 63%. When 16 false-positive samples that were co-infected with other enteropathogens were excluded, the specificity increased to 97%. We observed a significant decrease (51% vs. 68%) in the proportion of treated patients in this study compared to the pre-intervention period of our previous study (<i>p</i> = 0.04). In contrast, a minor, non-significant 5% increase (<i>p</i> = 0.60) was observed in this study compared with the post-intervention period (45% treated) from the previous study. These findings demonstrate that Ct-guided diagnostic strategies continue to enhance <i>C. difficile</i> diagnostic precision and help limit inappropriate antibiotic use in our pediatric population.