Background: The incidence of reported nontyphoidal Salmonellosis has increased during last decade in Korea. Salmonella typhimurium and Salmonella enteritidis are two major serotypes in nontyphoidal Salmonella. To determine the nature of potential outbreak S. typhimurium infection in a community, we retrospectively evaluated clinical and epidemiologic features of S. typhimurium infections and performed pulsed-field gel electrophoresis (PFGE) to investigate a genetic relatedness of S. typhimurium isolated in Guro Hospital.

Methods: From May 1998 to April 1999, a total of 20 S. typhimurium strains were isolated from 18 patients. PFGE patterns were analyzed for 20 S. typhimurium strains. Clinical and epidemiological features were evaluated from their medical records.

Results: Seventy two percent (13/18) were acute gastroenteritis, and 11% (2/18) were enteric fever and 16% (3/18) were intussusception. Seventy eight percent (14 of 18) of patients were six years old or less than. There were two major type (A, B) on PFGE analysis. Eight of 20 strains showed identical PFGE type (A1). Eleven strains were subtypes of A1. One strain showed different type (B). Similarity coefficients between A1 and its subtypes were all over 0.765 and they showed close genetic distance on dendrogram. Antibiogram of A1 eight strains were various.

Conclusions: High genetic relationship among 20 S. typhimurium strains for a year in Guro area indicates that they were possibly originated from one clone and that there might be a common source of infection. More efforts should be directed toward the epidemiological investigation of the cases to detect outbreaks and prevent further spread of the infection. (Korean J Clin Microbiol 1999;2:199-206)