A familial outbreak of verotoxin-producing Escherichia coli O103:H2 infection in which a calf was the suspected infectious source

Abstract

A familial outbreak of Verotoxin-producing Escherichia coli (VTEC) infection occurred in July 1996 in AKITA prefecture. Four VTEC strains harboring VT-1 and eaeA genes were isolated from three patients and a calf, breeding farm for which was located as close as 4 meters from the house where the patients lived in. All of the 4 VTEC isolates were serotyped as O63:H2 using commercially available sera kits. However, a patient isolate, EC-281, was serotyped as 0103:H2 at the International Escherichia and Klebsiella Centre. Titration and absorption tests using rabbit antisera raised against EC-281 confirmed that the serogroup of the remaining 3-VTEC isolates was also O103. Epidemiological characteristics including plasmid profile, antibiotic susceptibility patterns and pulsed-field gel electrophoresis patterns of the 4 VTEC isolates were completely the same, indicating that these isolates originated from a common source. These findings in conjunction with the results of epidemiological survey conducted by the Health Center suggested that a possible infectious source for this outbreak is the calf. Our present results strengthen the significance of calf as an infectious source of VTEC infection.