We describe the isolation of one strain of Shiga toxin-producing Escherichia coli O91:H21 from a child with diarrhea in the city of Porto Alegre, RS, Brazil. Considering the pathogenic potential of STEC, these organisms should be looked for more carefully among our population.
enterohemorrhagic E. coli; STEC; enteroaggregative E. coli; enteropathogenic E. coli; diarrhea