Gastrointestinal pathogens detected by multiplex nucleic acid amplification testing in stools of pediatric patients and patients returning from the tropics

Background: Gastrointestinal infections are caused by a broad spectrum of pathogens. Conventional diagnostic procedures are resource and time consuming due to single pathogen testing, often in different laboratories. Method: We analyzed 312 consecutive stool samples from pediatric patients (n=127) with gastroenteritis or from adult travelers returning from the tropics with suspected parasite infestation (n=185) using commercial multiplex nucleic acid amplification testing (NAT) (xTAG gastrointestinal pathogen panel, Luminex) covering 15 diarrhea-causing pathogens. The results of the positive samples and a representative number of negative samples were compared to standard methods, including NAT, direct antigen detection (DAD), bacterial culture and microscopy. Results: Of the 185 samples from adult travelers, 21 (11%) were multiplexNAT-positive, with enterotoxigenic Escherichia coli (4%) being the predominant pathogen. Microscopic examination revealed Blastocystis hominis in 23% not covered by the panel. MultiplexNAT scored positive in 66 pediatric samples (52%), with rotavirus (27%) being the most prevalent. All adenovirus-, rotavirus-, Clostridium difficile- and Cryptosporidium-positive samples were confirmed in external laboratories, but only 40% of norovirus- and 29% of Giardia-positive samples. Analysis of frozen specimens by bacterial culture showed the highest discrepancies with the multiplexNAT. Conclusion: Our study demonstrates broad detection of relevant gastroenteritis pathogens by multiplexNAT with a short turnaround time. This is important for diagnosis, infection control and empiric management of gastroenteritis patients, but may be selectively complemented by bacterial culture and resistance testing.