Aetiology of traveller's diarrhea: A nested case-control study

Background: Traveller's diarrhea (TD) is the leading cause of morbidity among travelers. Recently, molecular methods have been developed to detect the causative pathogens of TD. The aim of this study was to test a multiplex-PCR approach in patients with TD and asymptomatic controls. Methods: In total, 91 travelers (61 TD cases, 30 asymptomatic controls) prospectively collected stool samples during travel and documented gastrointestinal symptoms. Samples were analyzed using the BioFire (R) FilmArray (R) Gastrointestinal Panel, which covers 13 enteric bacteria (e.g. diarrheagenic Escherichia coli), 4 protozoan parasites and 5 viruses. Results: TD cases had more likely a positive test (46/61, 75%) compared to controls (17/30, 57%, p = 0.07). The most common enteric pathogens were enteroaggregative E. coli (36/91, 40%), followed by enterotoxigenic E. coli (31/91, 34%) and enteropathogenic E. coli (EPEC, 29/91, 32%). The only pathogens significantly associated with TD were EPEC (p = 0.01) and ETEC (p = 0.047). Protozoan parasites were not detected. Conclusion: Our results challenge the widespread use of multiplex-approaches covering numerous enteric pathogens in the diagnostic workup of TD because only few (i.e. diarrheagenic E. coli) were related to symptoms of TD.