Enterotoxigenic Escherichia coli and diffusely adherent E coli as likely causes of a proportion of pathogen-negative travelers' diarrhea-a PCR-based study. - Meraz IM; Jiang Z; Ericsson CD; Bourgeois AL; Steffen R; Taylor DN; Hernandez N; DuPont HL (Journal of Travel Medicine, 2008)