An outbreak due to enterohaemorrhagic Escherichia coli O157:H7 in a children day care centre characterized by person-to-person transmission and environmental contamination.

An outbreak of gastrointestinal disease and haemolytic uraemic syndrome caused by Escherichia coli O157:H7 was investigated. The outbreak occurred in a day care centre located in northern Germany in August 1992 and involved 39 children and two adults. Furthermore, four asymptomatic infections were detected among the staff. Initial and secondary cases were reported over a 30-day interval, with cases occurring in three waves. Person-to-person contact and environmental contamination were assumed to be the main mode of transmission. The source of the outbreak has remained unknown but it is likely that primary or secondary contamination of the day care centre's kitchen, too, played a role in the spread of infections. The organisms were isolated from two open packs of deep-frozen stuffed cabbage rolls and turkey scallops in batter, and furthermore from swabs from two kitchen utensils. Of the 39 cases with diarrhoea, three developed a haemolytic uraemic syndrome; one of the latter patients died. In 8 of the cases as well as in four healthy adult employees, E. coli O157:H7 was isolated from stool samples, and in two stool culture-negative cases the presence of IgM antibody to O157 LPS indicated recent infection. The E. coli O157:H7 isolates from the cases and the kitchen were of identical phage type and yielded identical biochemical reactions. All E. coli O157:H7 isolates harboured stable slt-II genes. However, slt-I genes could only be demonstrated in the primary cultures and were lost during subcultivation. This is the largest outbreak caused by enterohaemorrhagic E. coli O157:H7 that has been documented in Germany so far. The high infectivity of the organism which was demonstrated by person-to-person transmission and propagation within certain groups of children stresses the need for strict hygienic measures and early case reporting when such infections occur in susceptible settings like day care centres, nursing homes, or hospitals.