Abundance in Sewage of Bacteriophages Infecting Escherichia coli O157:H7

Bacterial virulence factors such as toxins are often encoded by bacteriophages. Among other examples, factors encoded by phages have been described in some of the emerging or re-emerging pathogens, including the pyrogenic exotoxin A production in group A streptococci (1 ), the cholera toxin in Vibrio cholerae (2 ), or enterotoxin production in enterohemorrhagic (EHEC) strains of E. coli (3 ).