Isolation of Shiga Toxin-producing Escherichia coli O157: H7 from Processed Salmon Roe Associated with the Outbreaks in Japan, 1998, and a Molecular Typing of the Isolates by Pulsed-field Gel Electrophoresis

Asai, Yasufumi; Murase, Toshiyuki; Osawa, Ro; Okitsu, Tadayuki; Suzuki, Riéko; Sata, Shin; Yamai, Shiro; Terajima, Jun; Izumiya, Hidemasa; Tamura, Kazumichi; Watanabe, Haruo

doi:10.11150/kansenshogakuzasshi1970.73.20

Cited by 23 publications

(20 citation statements)

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“…Such organisms should not be present on fresh-caught fish (Cha�opadhyay, 2000). The contamination of food of fish origin with pathogenic E. coli probably occurs during handling of fish and during the production process (Ayulo et al, 1994;Asai et al, 1999). …”

Section: Escherichia Colimentioning

confidence: 99%

“…Infection with verocytotoxin-producing strains of E. coli (VTEC) a�er ingestion of fish was recorded in Belgium (Pierard et al, 1999). An outbreak caused by salted salmon roe contaminated, probably during the production process, with enterohaemorrhagic E. coli (EHEC) O157 occurred in Japan in 1998 (Asai et al, 1999). The roe was stored frozen for 9 months but it appears that O157 could survive freezing and a high concentration of NaCl and retained its pathogenicity for humans (Semanchek and Golden, 1998).…”

Section: Escherichia Colimentioning

confidence: 99%

See 1 more Smart Citation

Fish: a potential source of bacterial pathogens for human beings

Novotny¹,

Dvorská²,

Lorencova³

et al. 2004

Vet. Med.

207

187

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ABSTRACT:Human infections caused by pathogens transmi�ed from fish or the aquatic environment are quite common and depend on the season, patients' contact with fish and related environment, dietary habits and the immune system status of the exposed individual. They are o�en bacterial species facultatively pathogenic for both fish and human beings and may be isolated from fish without apparent symptoms of the disease. The infection source may be fish kept for both for food and as a hobby.

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Section: Escherichia Colimentioning

confidence: 99%

Section: Escherichia Colimentioning

confidence: 99%

Fish: a potential source of bacterial pathogens for human beings

Novotny¹,

Dvorská²,

Lorencova³

et al. 2004

Vet. Med.

207

187

View full text Add to dashboard Cite

show abstract

“…It has been reported that at least 10 cells existing in food could cause human illness [6]. But Asai et al [7] found that only 0.75 to 1.5 viable cells of E. coli O157:H7 in salted salmon roe could cause the infection. In order to explain this phenomenon, Makino et al [8] re-estimated the number of E. coli O157:H7 cells in the implicated salted salmon roe from their membrane integrity, cell elongation and pathogenicity for mice, and found that almost all of E. coli O157:H7 cells had entered a viable but nonculturable (VBNC) state, thus the authors suggested that VBNC cells of E. coli O157:H7 in the food should be the source of the outbreak.…”

Section: Introductionmentioning

confidence: 98%

Induction of Viable but Nonculturable Escherichia coli O157:H7 by High Pressure CO2 and Its Characteristics

Zhao

Hao

et al. 2013

PLoS ONE

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The viable but nonculturable (VBNC) state is a survival strategy adopted by many pathogens when exposed to harsh environmental stresses. In this study, we investigated for the first time that whether high pressure CO2 (HPCD), one of the nonthermal pasteurization techniques, can induce Escherichia coli O157:H7 into the VBNC state. By measuring plate counts, viable cell counts and total cell counts, E. coli O157:H7 in 0.85% NaCl solution (pH 7.0) was able to enter the VBNC state by HPCD treatment at 5 MPa and four temperatures (25°C, 31°C, 34°C and 37°C). Meanwhile, with the improvement of treatment temperature, the time required for E. coli O157:H7 to enter VBNC state would shorten. Enzymatic activities in these VBNC cells were lower than those in the exponential-phase cells by using API ZYM kit, which were also reduced with increasing the treatment temperature, but the mechanical resistance of the VBNC cells to sonication was enhanced. These results further confirmed VBNC state was a self-protection mechanism for some bacteria, which minimized cellular energetic requirements and increased the cell resistance. When incubated in tryptic soy broth at 37°C, the VBNC cells induced by HPCD treatment at 25°C, 31°C and 34°C achieved resuscitation, but their resuscitation capabilities decreased with increasing the treatment temperature. Furthermore, electron microscopy revealed changes in the morphology and interior structure of the VBNC cells and the resuscitated cells. These results demonstrated that HPCD could induce E. coli O157:H7 into the VBNC state. Therefore, it is necessary to detect if there exist VBNC microorganisms in HPCD-treated products by molecular-based methods for food safety.

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“…The preservation of foods by high salt concentrations has been viewed historically as an effective means of preventing food-borne infections (11,13). However, an outbreak caused by salted salmon roe which was contaminated with enterohemorrhagic Escherichia coli (EHEC) O157 occurred in four independent places in Japan in 1998, with 62 cases reported (1). Since all the causative foods were manufactured by the same company, the salmon roe was probably contaminated with O157 during the production process.…”

mentioning

confidence: 99%

“…Although the definitive source of O157 could not be identified because the roe was stored frozen for 9 months, it appeared that O157 could survive freezing and a high concentration of NaCl (22) and retain its pathogenicity for humans. In addition, it was proved by the most probable number method that about 0.75 to 1.5 viable cells of O157 could cause infection (1). This number was considered to be very low for infection (23).…”

mentioning

confidence: 99%

Does Enterohemorrhagic Escherichia coli O157:H7 Enter the Viable but Nonculturable State in Salted Salmon Roe?

Makino

Kii

Asakura

et al. 2000

Appl Environ Microbiol

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An outbreak caused by salted salmon roe contaminated with enterohemorrhagic Escherichia coli O157 occurred in Japan in 1998. Since about 0.75 to 1.5 viable cells were estimated to cause infection, we presumed that O157 might enter the viable but nonculturable (VNC) state in salted salmon roe and consequently that viable cell numbers might be underestimated. Although patient-originating O157 cells could not grow on agar plates after 72 h of incubation in 13% NaCl, they were resuscitated in yeast extract broth, and more than 90% of the cells were shown to be viable by fluorescent staining, suggesting that almost all of them could enter the VNC state in NaCl water. Roe-originating O157 was resistant to NaCl because it could grow on agar after 72 h of incubation in NaCl water, but about 20% of cells appeared to enter the VNC state. Therefore, germfree mice were infected with O157 to examine the resuscitation of cells in the VNC state and the retention of pathogenicity. O157 that originated in roe, but not patients, killed mice and was isolated from the intestine. However, these isolates had become sensitive to NaCl. O157 cells of roe origin incubated in normal media also killed mice and were isolated from the intestine, but they also became transiently NaCl sensitive. We therefore propose that bacterial cells might enter the VNC state under conditions of stress, such as those encountered in vivo or in high salt concentrations, and then revive when those conditions have eased. If so, the VNC state in food is potentially dangerous from a public health viewpoint and may have to be considered at the time of food inspection. Finally, the establishment of a simple recovery system for VNC cells should be established.In Japan, salmon roe is soaked in a liquid seasoning, which consists of soy sauce (79.0%), water (14.0%), chemical seasoning (6.5%), synthetic sake (0.3%), and a fermented seasoning (0.2%); its salt content is equal to a 13% NaCl concentration. This salted salmon roe is a popular component of Japanese sushi. The preservation of foods by high salt concentrations has been viewed historically as an effective means of preventing food-borne infections (11, 13). However, an outbreak caused by salted salmon roe which was contaminated with enterohemorrhagic Escherichia coli (EHEC) O157 occurred in four independent places in Japan in 1998, with 62 cases reported (1). Since all the causative foods were manufactured by the same company, the salmon roe was probably contaminated with O157 during the production process. Although the definitive source of O157 could not be identified because the roe was stored frozen for 9 months, it appeared that O157 could survive freezing and a high concentration of NaCl (22) and retain its pathogenicity for humans. In addition, it was proved by the most probable number method that about 0.75 to 1.5 viable cells of O157 could cause infection (1). This number was considered to be very low for infection (23). Recently, it has been reported that Vibrio cholerae, E. coli, Campylobacter jejuni, ...

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Isolation of Shiga Toxin-producing Escherichia coli O157: H7 from Processed Salmon Roe Associated with the Outbreaks in Japan, 1998, and a Molecular Typing of the Isolates by Pulsed-field Gel Electrophoresis

Cited by 23 publications

References 0 publications

Fish: a potential source of bacterial pathogens for human beings

Fish: a potential source of bacterial pathogens for human beings

Induction of Viable but Nonculturable Escherichia coli O157:H7 by High Pressure CO2 and Its Characteristics

Does Enterohemorrhagic Escherichia coli O157:H7 Enter the Viable but Nonculturable State in Salted Salmon Roe?

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