Optimizing laboratory workflow for the diagnosis of Clostridiodes difficile infection in a medical center in Northern Taiwan

Abstract

Background/purpose: There are few attempts at diagnosis among physicians who pay less attention to Clostridiodes difficile infection (CDI) and think that one-step enzyme immunoassay (EIA) toxin tests and anaerobic cultures are untrustworthy. Methods: This study investigated patients that had loose stool more than 3 times/day after admission from April 2016 to January 2017. We replaced the one-step toxin rapid test and culture with a two-step rapid test of glutamate dehydrogenase (GDH) and toxins, and we optimized the process of microbiology culture. PCR for toxin genes (tcdA and tcdB) and PCR ribotyping of the isolates were also performed. We compared the results obtained from enzyme linked immunosorbent assay (ELISA), EIA kits for GDH and toxins, and culture in terms of accuracy. Results: A total of 52 cases were enrolled and 22 isolates were identified, which comprised 20 ribotypes017 and 2 ribotypes078. ELISA and EIA (QuikChek) had the best results in GDH detection with sensitivities of 86.4% and 81.8%, respectively. CLO and CHROMagar methods showed 100% positive predictive value, but CLO agar had better negative predictive value (81.1%). According to the receiver operating characteristic (ROC) curve, VIDAS (ELISA), QuikChek (EIA), and CLO agar showed the best performance with areas under the curve of 0.932, 0.909, and 0.841, respectively. Veda (EIA) presented the highest false-positive rate of 26.7%. VIDAS showed the least positive toxin findings but zero falsepositive findings. Conclusions: Ribotype 017 prevailed in our hospital. ELISA and QuickChek (EIA) showed better sensitivity and specificity in GDH detection than most EIA rapid kits.

Keywords

• Clostridiodes difficile
• Clostridium difficile
• Glutamate dehydrogenase
• ELISA
• EIA
• Selective medium