Epidemiology and molecular identification of Salmonella infections in children.

OBJECTIVE To explore the role of foods and the environment in the development of infections with Salmonella in infants and children. DESIGN Case-controlled survey and the use of pulsed-field gel electrophoresis to establish DNA fingerprint patterns. SETTING Ambulatory and hospitalized patients at a children's hospital. PATIENTS OR OTHER PARTICIPANTS A consecutive sample of children younger than 4 years old who were infected with Salmonella and 3 age-matched controls per patient were to be surveyed. Of the 103 eligible cases of salmonellosis, 90 cases and 264 controls were included in the study. DATA ANALYSIS Univariate analysis was done using the Mantel-Haenszel chi2 test or the Fisher exact test. The Bonferroni correction was used for multiple comparisons. DNA fingerprints were inspected for identical banding. RESULTS Results demonstrated similar diets between cases and controls with the exception of more potato or macaroni salad or coleslaw consumption in the control group (P<.001). DNA fingerprints of Salmonella newport and Salmonella typhimurium demonstrated that all cases were due to unique isolates except in 5 instances involving 12 patients. Seven of these patients could be connected geographically. CONCLUSIONS Most of the cases of salmonellosis in children younger than 4 years are of a sporadic nature and the major source of infection remains unidentified. For patients infected with identical isolates of Salmonella, a common food source could not be incriminated with the methods used. Environmental contamination or other sources of Salmonella are suggested by these epidemiological data.