Usefulness of Stool Multiplex Polymerase Chain Reaction Assays in Patients with Acute Diarrhea

Background/Aims: There is a recent increase in the use of stool multiplex PCR assay-based diagnostic tests in patients with acute diarrhea. We used multiplex PCR assays to analyze the distribution of diarrhea-causing bacteria and viruses, as well as the clinical features of patients with acute diarrhea. Methods: We retrospectively reviewed stool specimens of inpatients complaining of acute diarrhea from October 2018 to July 2020. The stool specimens had been tested for bacteria and viruses using multiplex PCR assays. Results: A total of 414 stool specimens from 346 patients were tested, and 152 pathogens were detected in 131 stool samples (131/414, 31.6%). Co-infection was detected in 20 patients (20/346, 5.8%). The common pathogens detected as causes of acute diarrhea, including co-infection, were Clostridium perfringens (34.9%), Clostridioides difficile (19.7%), and Campylobacter spp. (18.4%). The average age of patients with multiplex PCR-positive tests was lower than those with multiplex PCR-negative tests (p=0.001). In patients with suspected C. difficile infection (CDI), the RT-PCR for toxin gene assay was performed in 370 stool samples, 35 of which were positive (9.5%). Furthermore, 16 of the 35 samples were positive on the multiplex PCR assay (45.7%). Conclusions: The multiplex PCR assay revealed that C. perfringens was the most common diarrhea-causing pathogen. In addition, in patients with suspected CDI, the multiplex PCR assay alone was insufficiently sensitive to detect pathogens and a conventional CDI test was additionally required.