An outbreak of Salmonella enterica serovar Othmarschen at a funeral service in Guri-si, South Korea.

*Corresponding author: Mailing address: Division of Enteric Bacterial Infections, Center for Infectious Diseases, National Institute of Health, #5 Nokbun-dong, Eunpyung-gu, Seoul, 122-701, Republic of Korea. Tel: +82-2-380-1462, Fax: +82-2-352-4767, E-mail: [email protected] Salmonella is one of the major contagious enteric pathogens regularly implicated in cases of food-borne disease in Korea. The most frequent serovars isolated from human beings in Korea were Salmonella enterica serovar Enteritidis, Salmonella enterica serovar Typhimurium, and Salmonella enterica serovar Typhi. These serovars were responsible for over 63% of food-borne illnesses recorded during 2004 2005 (1). However, Salmonella enterica serovar Othmarschen is a relatively rare serovar which has been isolated from humans as well as animals in Korea. S. Othmarschen was isolated from humans and calves, and a nosocomial outbreak of S. Othmarschen harboring a plasmid encoding for extendedspectrum beta-lactamase TEM-27 was described in previous studies (2-4). In this report, we describe a significant outbreak of S. Othmarschen, which resulted in severe salmonellosis, among persons attending a funeral service in Guri-si. On March 20, 2007, a doctor notified a regional health center that 12 persons, including the chief mourner and condolers, had been admitted to hospitals due to complaints of severe diarrhea and abdominal pains. After this notice, a team of epidemiological investigators conducted interviews, obtained specimens, and evaluated the specimens for pathogens. Their investigations revealed that 300 persons had attended the funeral service and had possibly consumed a common suspicious dish. Among these persons, 72 became ill and had been hospitalized at 22 different hospitals. There were no mortality. The food eaten by the mourners had been provided by a food supplier specialized in the catering of funeral services. According to the results of the interviews, the patients had primarily dined on pan-fried foods containing eggs, squash, and seafood. The principal symptoms reported were diarrhea (98.3%), abdominal pain (96.6%), fever (89.7%), rigor (86.2%), headache (74.1%), nausea (70.7%), and vomiting (37.9%). With regard to the most general symptoms, patients suffered from yellow or white watery diarrhea for a period of 1 to 5 days, with a maximum of 50 incidents. One patient required kidney dialysis due to acute renal failure resulting from dehydration consequent to consecutive diarrheal episodes. We collected a variety of specimens, including rectal swabs from patients and food handlers, the remaining food, the ingredients of the foods, and tools and utensils, including the chopping board, knives, and dish towels utilized by the caterers. Microbiological examinations were then conducted on the specimens. S. Othmarschen (antigenic formula: 6, 7:g, m:-) was isolated from 3 samples of the remaining food, all of which were pan-fried foods that contained eggs, squash, and seafood, as well as from a food handler and 35 patients. We conducted antibiotic susceptibility tests and pulsed-field gel electrophoresis (PFGE) with the XbaI or BlnI restriction enzymes, using the PulseNet standard method for Salmonella serovars (5). All 39 of the isolates were found to be susceptible to 16 antibiotics employed in our laboratory, and the isolates uniformly evidenced an indistinguishable pattern from both XbaI PFGE and BlnI PFGE (Fig. 1). These results strongly indicated that an infected food handler or the contaminated foods themselves represented the origin of the outbreak. For the purpose of comparison of the PFGE pattern with those of overseas S. Othmarschen isolates, we uploaded the PFGE results and requested comparison data from PulseNet Asia Pacific Forum homepage (https:// pulsenetap.esr.cri.nz/). Through the homepage system, PulseNet USA verified that the XbaI PFGE pattern of S. Othmarschen from the outbreak was indistinguishable from their most frequently detected S. Othmarschen PFGE pattern,