Molecular typing of enterohemorrhagic Escherichia coli O157:H7 isolates in Japan by using pulsed-field gel electrophoresis

Abstract

Pulsed-field gel electrophoresis (PFGE) was applied for molecular typing of 825 enterohemorrhagic Escherichia coli (EHEC) O157:H7 isolates, most of which were from 19 outbreaks and 608 sporadic cases in Japan, mainly in May to August 1996. By PFGE, the EHEC O157:H7 isolates were classified into six types (type I to V and ND [nondescript]) and UT untypeable isolates. Fifty isolates from seven outbreaks in May to June and 60 isolates from patients with sporadic cases of infection showed almost identical PFGE patterns which differed in only 1 of 22 DNA fragments. They were classified into type I. Ninety-nine isolates from 10 other outbreaks and 156 isolates from patients in the Kinki area with sporadic cases of infection obtained in the early summer of 1996 showed identical PFGE patterns, suggesting that they were derived from one huge outbreak. They were classified into type II. Type IV EHEC isolates, which had only the stx2 gene, caused another outbreak in a primary school in June. EHEC isolates of two other types, types III and V, were not related to the outbreak but were isolated in several parts of Japan. ND EHEC isolates included a variety of patterns which could not be classified into either of the types mentioned above. Twenty-five isolates could not be analyzed due to degradation of their genomic DNAs and were represented as UT. These results indicate that EHEC O157:H7 strains with various PFGE types have already spread to Japan and caused the multiple outbreaks and sporadic infections in Japan in the summer of 1996. Enterohemorrhagic Escherichia coli (EHEC) (or Shiga toxin-producing Escherichia coli) O157:H7 is an important foodborne pathogen causing abdominal cramps, diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome (HUS) (6). Recently, EHEC O157:H7 infection has frequently been reported and has been epidemiologically linked to undercooked ground beef (5), water (11), and other foods (1, 2, 4). In Japan, an EHEC O157:H7 outbreak occurred in a kindergarten in Urawa City, Saitama Prefecture, in 1990, and 2 of 268 patients died of HUS. This outbreak was attributed to well water contaminated with EHEC O157:H7. In May 1996, an outbreak of EHEC O157:H7 occurred in primary schools in Oku City, Okayama Prefecture, and involved 138 symptomatic patients, 2 of whom died of HUS.

Molecular typing by pulsed‐field gel electrophoresis of Flavobacterium psychrophilum isolates derived from Japanese fish

“…However, the molecular typing data obtained by these methods do not directly correlate with the results of this study. Generally, PFGE allows detailed analysis of the molecular typing of various bacteria, for example, E. coli O157 (Izumiya et al 1997), and thus in this study PFGE was used to type F. psychrophilum.…”

“…However, molecular epidemiology that uses the whole genome of F. psychrophilum is not well understood. Restriction fragment length polymorphism analysis of the whole genome of bacteria by pulsed-field gel electrophoresis (PFGE) is a useful tool for detailed genotyping analysis of various pathogenic bacteria such as Escherichia coli, Staphylococcus and Salmonella (Izumiya, Terajima, Wada, Inagaki, Itoh, Tamura & Watanabe 1997;Vanderlinde, Fegan, Mills & Desmarchelier 1999;Shibata, Shirakata, Kawasaki, Sato, Kuwahara, Ohnishi, Arakaki & Higuti 2003;Kubota, Barrett, Ackers, Brachman & Mintz 2005). In order to understand the molecular epidemiology of CWD in various fish, we investigated F. psychrophilum isolates derived from several CWD outbreaks in Japan using both PCR-RFLP and PFGE.…”

Comparison of PCR-RFLP and PFGE for determining the clonality of enterohemorrhagicEscherichia colistrains

“…Pulsed-field gel electrophoresis (PFGE) is a commonly used molecular typing method for identifying strains responsible for disease outbreaks and has been used for a variety of pathogens, including EHEC, because of its high resolution and reproducibility (Terajima et al, 1999Izumiya et al, 1997;Johnson et al, 1995;Terajima et al, 2000;Barrett et al, 1994;Grif et al, 1998;Karch et al, 1995). However, there are several disadvantages associated with PFGE.…”

Isolation and characterization of Escherichia coli O157 from retail beef and bovine feces in Thailand

“…Isolation of E. coli O157:H7/H 3 has been reported very often from developed countries [1,2]. A big outbreak and many sporadic cases due to E. coli O157:H7 occurred in 1996 in Japan [3]. However, isolation of E. coli belonging to serogroup O157 has rarely been reported in Asian countries except Japan ; isolation of E. coli O157 from clinical sources in India, China, Korea, and Hong Kong has been brie£y reported [1,4^6].…”