Comparison of several Real-Time PCR Kits versus a Culture-dependent Algorithm to Identify Enteropathogens in Stool Samples

Abstract

This study aims to validate the current diagnostic method for the clinical detection of gastroenteritis. We analyzed 400 stool samples to detect three of the most common enteropathogens: Salmonella spp., Campylobacter spp., and Yersinia enterocolitica. All specimens were tested with a routine clinical diagnosis algorithm and with five real-time PCR assays. A total of 98 specimens (24.5%) were positive for enteropathogens. We found 24 samples positive for Salmonella enterica, 71 positive for Campylobacter spp., and 4 positive for Yersinia enterocolitica. All evaluated methods exhibited a good performance in identifying Salmonella and Yersinia enterocolitica, being the highest positive percent agreement (PPA) value of 95.8% and 100%, respectively. The clinical algorithm showed the highest PPA value identifying Salmonella, due to the enrichment in selenite broth. However, the evaluated methods showed notable differences in the identification of Campylobacter species, obtaining a wide range of PPA values: 59.2%-100%. The clinical algorithm showed the lowest PPA value since it was only able to detect Campylobacter jejuni and Campylobacter coli species. This study revealed the importance of implementing the real-time PCR technique in a clinical algorithm: it improved the accuracy of the diagnosis and provided results in a shorter time compared to routine clinical methods.