Phylogenetic analysis of Salmonella enterica serovar Enteritidis isolated from food poisoning outbreaks and sporadic infections in 2001-2002 in Hyogo prefecture: existent of predominant genotypes in the epidemic.

*Corresponding author: Tel: +81-78-511-6787, Fax: +81-78-5317080 Since 1989, Salmonella enterica serovar Enteritidis has become the most prevalent among the Salmonella isolates in Japan (1). We previously analyzed, by means of phylogenetic dendrograms of pulsed-field gel electrophoresis (PFGE), genetic variations of the Salmonella isolates from 28 food poisonings in 1997-2000 (2,3) and 55 cases of sporadic infections in 1996-2000 (4). In the present study, we analyzed isolates from 15 food poisonings and 12 sporadically infected cases in 2001-2002 and compared the results with those of the above cases in 1996-2000. We found predominant genotypes throughout the epidemics that took place over the past several years in our prefecture. We analyzed a total of 34 specimens; 22 isolates in 15 food poisoning outbreaks (15 from stool specimens and 7 from suspected foods) and 12 isolates (all from stool specimens) in 12 sporadic infections (Table 1). The identified phage types (PTs) of these isolates were PT1, PT1/1b, PTlc, PT4, PT6, PT14b, PT29, PT36, and PT47 (Table 1). As in previous cases (2-4), there was no correlation between PTs and PFGE patterns (see Table 1 and Figs. 1 and 2). Antibiotic sensitivity test using antibiotic disks (Becton Dickinson Microbiology Systems, Cockeysville, Md., USA) (5) revealed that all the