EPIDEMIOLOGY AND MOLECULAR IDENTIFICATION OF SALMONELLA INFECTIONS IN CHILDREN. 1093

Abstract

Human epidemics of Salmonella are commonly attributed to the ingestion of contaminated foods, but the role of foods in the development of disease in infants and children is not understood. The purpose of this study was to delineate the role of foods and the surrounding environment in the development of infections with Salmonella in infants and children. The families of children < 4 years of age who were infected withSalmonella between July 1993-June 1995 were given an extensive questionnaire about exposures, food preparation and consumption, pets in the home, and day care attendance. Three age-matched controls per patient were also queried. The two commonly isolated serotypes of Salmonella underwent restriction enzyme digestion (SpeI, XbaI) followed by pulsedfield gel electrophoresis in order to establish DNA fingerprint patterns. These patterns were visually inspected for similarities. Ninety cases and 264 controls were evaluable at the completion of the study. Univariate analysis of data demonstrated that controls rather than cases were more likely to have consumed food considered to be high risk (e.g., cole slaw, whole milk, uncooked apples, turkey; p<0.05), receive support from WIC (p<0.02) and Medicaid (p<0.01), and boiled their water prior to mixing formula(p<0.05). S. newport and S. typhimurium were the most common isolates recovered (62%) and the DNA fingerprinting data from these isolates demonstrated 23 unique patterns for S. newport and 21 forS. typhimurium. Identical fingerprint patterns were found in 4 fingerprint clusters involving 10 patients with S. newport and in one cluster involving 2 patients with S. typhimurium. Review of the demographic data demonstrated that 7 of the children had a history of living or traveling to the same town as others with identical isolates. Although the majority of cases of salmonellosis in children encountered were sporadic, molecular fingerprinting demonstrated that at least 14% of our cases were infected with isolates identical to that of another child. The lack of common epidemiologic factors implicating contaminated foods suggests that environmental contamination remains important in the development of salmonellosis in infants and children. Until the role of environmental contamination is understood, prevention of this disease will not occur.