Food-borne outbreak caused by Salmonella enterica serovar Enteritidis in Bari, Italy.

This paper presents data from an epidemiologic investigation of an outbreak of gastroenteritis that occurred in Bari, Southern Italy, in June 2005. The source of the outbreak was traced to consumption of rice "arancini" (a typical Italian food prepared with rice, mozzarella cheese, eggs and bread crumbs), prepared in a traditional bakery in town. Salmonella enteritidis strains were isolated from affected patients, bakery personnel and food items. Isolates were analysed by using traditional microbiological methods to determine their serotype, by testing resistance to antimicrobial agents, and by pulsed-field gel electrophoresis (PFGE) profiling. Epidemiologic investigation showed a strong association between the consumption of rice "arancini" and illness (RR: 7.0; 95% CI: 1.14 - 40.97; p < 0.001). All outbreak isolates of Salmonella enteriditis had identical PFGE patterns and this result confirmed the source of infection. The data obtained in this study confirms the value of molecular typing by PFGE, in epidemiologic investigations of outbreaks caused by S. enteritidis. With proper standardization, molecular typing of S. enteritidis strains, in conjunction with established typing methods, could eventually form the basis of an effective epidemiologic surveillance system that would be invaluable in developing rational strategies for control and better understanding of its pathogenicity for man.