A foodborne outbreak of Vero cytotoxin-producing Escherichia coli O157 : H-phage type 8 in hospital

This paper describes the epidemiological and microbiological aspects of the largest outbreak of Vero cytotoxin-producing Escherichia coli O157 (VTEC O 157) infection in a hospital setting in which the route of transmission was foodborne. The outbreak, which was caused by a relatively uncommon phage t ype of VTEC O157, occurred in four geriatric continuing care wards in May 1 997. The total number of people found to be excreting the organism was 37, of whom 16 were inpatients and 11 were staff. Twelve people displayed enter ic symptoms. In addition, all but two of 10 cases identified in the local c ommunity were thought to be associated with the outbreak. An epidemiologica l investigation amongst the hospital patients revealed a statistically sign ificant association between VTEC O157 infection and attendance at a concert party on the continuing care wards on 17 May 1997 (relative risk = 3.22; P = 0.006). There was an even stronger relationship between consumption of h ome-baked cream-filled cakes brought to that party and evidence of infectio n (relative risk 19.35; P = 0.00002). Further investigations in the local c ommunity, coupled with microbiological evidence, supported the epidemiologi cal finding that homemade cream cakes brought into the hospital were the ve hicle of infection for the outbreak. There was no secondary spread within t he hospital. The outbreak serves as a reminder of the hazard posed by foods tuffs brought into a hospital from outside. (C) 2001 The Hospital Infection Society.