Whole-genome sequencing of Escherichia coli O7:H4

A large-scale food poisoning outbreak involving about 3000 elementary and junior high school students was caused by Escherichia coli O7:H4. The strain was isolated from faecal specimens of the patients, a seaweed salad, and red seaweed (Gigartina tenella). All strains were confirmed to be of the same origin by pulsed-field gel electrophoresis and single nucleotide polymorphism analysis.