A food-borne outbreak of gastroenteritis caused by different Salmonella serotypes in 2 universities in Xiamen, Fujian, China, in 2012

Abstract

We investigated a diarrhea outbreak in 2 universities to identify the etiological agent responsible, the source of infection, the mode of transmission, and the risk factors. A case-controlled study was conducted using case students and asymptomatic control students who were selected randomly and frequency-matched according to class and age, and the source of food or water intake was investigated. Of the total 22,404 students at the universities, 0.25z developed Salmonella Infections. A total of 96z(54/56) of the case students and 30z(35/117) of the control students consumed bread products provided by the same vendor (odds ratio [OR] ＝ 63.3; 95z confidence interval [CI], 14.9–550.7). Among the students who consumed bread, 96z (52/54) of the case students and 9z (3/35) of the control students ate egg sandwiches (OR ＝ 277.3; 95zCI, 43.9–1,750.8). Seven strains of Salmonella enteritidis and 6 strains of S. chester were isolated from the case students or food samples. Pulsed-field gel electrophoresis typing showed the same patterns. The outbreak of gastroenteritis was caused mainly by egg sandwiches contaminated with different serotypes of Salmonella.