[Salmonella enteritidis outbreak in a home for the aged]

An outbreak of gastroenteritis caused by Salmonella Enteritidis (SE), phagotype 1, reported at a senior citizen living facility in Burgos on November 15, 1999 is discussed. The objective of the research of this outbreak was that of ascertaining the source of infection, the mechanism by which it was transmitted and to propose the suitable measures for preventing any recurrence of this problem.

An observational retrospective cohort study has been made by surveying 106 of a total of 119 residents and 9 employees at the center in question. The Relative Risk of being affected by this disorder has been estimated in terms of the intake of different foods. Logic Regression was employed for calculating the odds ratio adjusted by age, sex and by the intake of foods and wine. The concordance of the clinical diagnosis with the coproculture diagnosis was studied using the Cohen's Kappa index of agreement.

A total of 42 individuals reported symptoms (37 residents and 5 employees). The clinical attack rate was 36.5%. Forty-five (45) of the 91 coprocultures performed (82 on residents and 9 on employees) were positive (41 in residents and 4 in employees). The attack rate for cases confirmed by coproculture was 49.5% among those investigated. Fried breaded milk and flour batter sweets was the food product implicated epidemiologically with the onset of the outbreak: RR 3.25 (C.I at 95% 1.10-9.59). The protective effect of the wine (Odds Ratio: 0.68) was not high enough to be statistically significant (p = 0.36). The Kappa index was 0.43 (p < 0.001), which reveals very little agreement between the clinical diagnosis and the coproculture diagnosis.

Epidemiological evidence exists of the intake of fired breaded milk and flour batter sweets having been the mechanism for the transmission of the infection, and the food product in question having been stored at room temperature having been the determining contributing factor in the start of the outbreak. This reveals that the best way of preventing this type of outbreaks are clean habits and practices on the part of all those involved in the food-handling sector.