Publications

Abstract

Traditional processing of stool for gastrointestinal (GI) pathogens is labor intensive, involves multiple tests, and turnaround times may be up to 72 hours, depending on laboratory workflow. The future of diagnostic testing in clinical microbiology will involve on-demand multiplex molecular methods for detection of pathogens directly from clinical specimens. Some panels allow for simultaneous testing of multiple targets from a small sample size with turnaround times under 4 hours, allowing for rapid management of diarrheal disease and contact tracing for organisms of public health significance. A total of 126 stool samples submitted to the UVA Clinical Microbiology Laboratory for routine testing were included in the evaluation. Not all samples were able to be tested with all available platforms. Three multiplex molecular enteric panels (BD MAX™, BioFire FilmArray®, and Verigene®) were compared to traditional culture, EIA methods and Ova & Parasites (O&P) for detection of GI pathogens. Of 43 samples tested with routine methods and all molecular tests, 100% agreement was seen in 14 samples (1 negative, 13 positive). An added 25 samples agreed among all molecular methods, (3 positive, 22 negative) with discrepant EIA results (primarily Campylobacter). Of 4 discrepant samples, 2 were positive with FilmArray® and traditional methods (1 Campylobacter and 1 Shiga-toxin) and 2 were positive by FilmArray®, Verigene® and traditional methods (both Shigella). FilmArray® accurately detected E coliO157:H7 in 3 samples. There was 100% correlation between 60 samples tested for Norovirus and Rotavirus with FilmArray® and Verigene®. Both methods detected Norovirusin 5 samples and Rotavirus in 1 sample. Giardia was detected with FilmArray® and EIA in 13 of 52 samples. Two samples positive by EIA were negative by FilmArray® and routine O&P. The multiplex panels accurately identified multiple pathogens from 17 samples. A comparator was not available for all organisms. The accuracy for detections of GI targets was excellent for all three multiplex panels. While we were aware of potential false positive results with the EIA methods in use, this study indicates it was as high as 75% for Campylobacter. The ability to rapidly and accurately identify GI pathogens in clinical samples is valuable for contact tracing and disease management.