Background: DNA based identification methods (PCR) have largely replaced bacterial culture for the etiologic diagnosis of infectious gastroenteritis. PCR based methods allow for detection of pathogens hitherto not tested for using routine cultures. Their clinical relevance however is uncertain, as there is a paucity of clinical experience linking PCR detected pathogens to particular clinical presentations. Enteropathogenic Escherichia coli (EPEC) are among the more frequently detected bacteria in stool samples, and while recognized as a cause of acute diarrhea in children, their role as pathogens in adults is less well established. The aim of this study was to investigate whether there are differences in clinical presentations, underlying comorbidity, and seasonality in patients hospitalized with diarrheal disease and diagnosed with EPEC as opposed to campylobacter, salmonella and shigella. Furthermore, to investigate patterns of co-infections, and whether the positive EPEC tests are of the subtype typical, which have been linked to diarrhea, or atypical EPEC. Methods: A retrospective study of all 361 patients over 18 years testing positive for EPEC, campylobacter, salmonella or shigella with a PCR based method in Akershus University Hospital between November 2013 and November 2015. A structured review of medical records was preformed and patients categorized in to two groups; EPEC single infected (n=82) and control group (n=279) for comparison. Results: In EPEC single infected 68 % of the patients presented with acute diarrhea, 14 % with chronic diarrhea and 18 % had no diarrhea. In the control group the results were 86 %, 9 % and 4 % respectively, with a significant difference in acute diarrhea and no diarrhea. 33 % of EPEC was found as part of a co infection, a higher rate than for all the other bacteria and significantly higher than for campylobacter with 17 %. Underlying cancer was found in 27 % of EPEC single infected, compared to 13 % in the control group (P < 0, 05). The rate of immunosuppressed and organ transplanted patients was higher in EPEC single infected, while the rate of intestinal illness and patients with IBD was higher in the control group, but neither differences reached significance. 18 % of EPEC single infected and 37 % of the control group had positive travel history, a significant difference. EPEC single infected showed no seasonality, while the control group had a peak during summer. 93 % were atypical EPEC and 7 % were typical. Conclusion: This study shows that EPEC is associated with acute diarrhea in adults. However, in EPEC positive fecal samples co infections was detected significantly more often than for campylobacter and salmonella, and EPEC single infected patients had a significantly higher rate of “no diarrhea” than the other gastroenteritis pathogens, suggesting that EPEC may also appear as an innocent bystander. More patients with EPEC single infection than the control group had underlying cancer, fewer had a positive travel history and EPEC showed no seasonality. The large majority of the EPEC infections were with the subtype atypical EPEC.