To The Editors:
Enterohemorrhagic Escherichia coli O157 is an important emerging gastrointestinal pathogen that is associated with hemolytic uremic syndrome and encephalopathy. In 1996, 22 food-borne outbreaks of E. coli O157 infection involving 9054 patients occurred in Japan,1 but the source of infection was identified in only a few of the outbreaks. Several reports have suggested a relationship with undercooked ground beef in other countries.2, 3
In August, 1997, we came across sporadic E. coli O157 infection in Tsu city, with a population of 160 000. Six children, 3 boys and 3 girls, were admitted to the National Mie Hospital (Table 1). Cases 2 and 3 were siblings. The onset of hemorrhagic colitis occurred between August 3 and 8. One case (Case 1) was complicated by hemolytic uremic syndrome, and 2 cases (Cases 2 and 3) had transient hematuria which resolved quickly. The results of pulsed-field gel electrophoresis4 suggested that all 6 isolates of E. coli O157 from these patients had identical genomic profiles.
All 6 patients had a history of beef intake, and the dates of intake were limited to a 3-day period (August 1 to 3). Three of the children (Cases 1, 4 and 6) had eaten raw beef. Softened raw beef is a Korean-style food called "yukke." Sliced raw beef is "beef sashimi," named after "raw fish sashimi" which is popular in Japan. Patients 2, 3 (siblings) and 5 had eaten beef that had been bought at the same butcher shop and cooked at home in Japanese barbecue style.
When Japanese people prepare Japanese barbecue, they use chopsticks to handle the meat while it is roasting. They often use the same chopsticks for eating, creating the potential for ingesting bacteria that contaminated the raw beef.
Inadequate washing of hands and cooking tools is a risk factor for E. coli O157 infection contracted from homemade hamburgers in the US.5 Similarly the use of the same chopsticks for cooking and eating can cause this disease.
The habit of eating raw beef in Japan could also spread the infection if the beef is contaminated. Younger children who are very susceptible to this enteropathogenic organism should avoid exposure to these risk factors.
We are grateful to the Mie Prefectural Government and the Tsu Public Health Center for their cooperation in our epidemiologic investigations.
Takashi Nakano, M.D.
Tatsuro Nobutoki, M.D.
Akira Sugiyama, Ph.D.
Toshiaki Ihara, M.D.
Hitoshi Kamiya, M.D.
Department of Pediatrics; National Mie Hospital (TNa, TNo, TI, HK)
Section of Microbiology; Mie Prefectural Institute of Public; Health (AS)
Tsu, Mie, Japan
1. Food Sanitation Division, Environmental Health Bureau, Ministry of Health and Welfare. The epidemiological data of food poisoning in Japan
2. Riley LW, Remis RS, Helgerson SD, et al. Hemorrhagic colitis associated with a rare Escherichia coli
serotype. N Engl J Med 1983;308:681-5.
3. LeSaux N, Spika JS, Friesen B, et al. Ground beef consumption in noncommercial settings is a risk factor for sporadic Escherichia coli
O157: H7 infection in Canada. J Infect Dis 1993;167:500-2.
4. Barrett TJ, Lior H, Green JH, et al. Laboratory investigation of a multistate food-borne outbreak of Escherichia coli
O157: H7 by using pulsed-field gel electrophoresis and phage typing. J Clin Microbiol 1994;32:3013-7.
5. Mead PS, Finelli L, Lambert-Fair MA, et al. Risk factors for sporadic infection with Escherichia coli
O157: H7. Arch Intern Med 1997;157:204-8.