Comparison of Illumigene, Verigene, and Amplivue for Rapid Molecular Detection of Clostridium difficile in Pediatric Stool Specimens

Background: Pediatric Clostridium difficile infection (CDI) has been steadily rising over the past decade and is associated with increased morbidity and mortality. Rapid and accurate diagnostic testing is important in medical management. Due to the low sensitivity of enzyme immunoassays, and the complexity of culture based methods, many labs are utilizing newer molecular techniques for direct detection of nucleic acid in stool. Methods: 59 prospective stool specimens from 57 pediatric patients (aged 4 months to 19 years) with suspected CDI were tested over a 4 month period. Three FDA-cleared molecular platforms, Meridian Illumigene, Nanosphere Verigene, and Quidel AmpliVue, were compared. All samples had a consistency rating (CR) from 1 - 5 (watery - solid) assigned and were refrigerated prior to testing. Those with a CR=5 were excluded. Six positive specimens were frozen for 3 months then retested, and two of those were serially frozen, thawed, and retested 5 more times over 5 months. Results: All 3 platforms agreed for 55 (93%) specimens. There were 17 positive and 38 negative results. Five positive specimens were called BI/NAP1/027 by Verigene. Of the 4 discrepant results, 3 (2 CR=3, 1 CR=2) were invalid by Illumigene and negative by the other platforms. One sample (CR=4) was Verigene indeterminate, Illumigene positive, and AmpliVue negative. All frozen specimens gave correct results on all platforms. Conclusions: These data suggest that each platform offers a viable solution for rapid diagnosis of CDI in children. Additionally, long term frozen samples can be tested reliably.