Jpn. J. Infect. Dis., 58, 2005

Laboratory and Epidemiology Communications

Mass Food Poisoning Caused by Beef Offal Contaminatedby Escherichia coli O157
Midori Maruzumi*, Mika Morita, Yumiko Matsuoka, Atsuko Uekawa1,
Tsutomu Nakamura1 and Kozo Fuji
Kumamoto City Environmental Research Institute, Kumamoto 862-0946 and1
Kumamoto City Public Health Center, Kumamoto 862-0976, Japan
Communicated by Haruo Watanabe(Accepted October 31, 2005)
Table 1. Results of the outbreak

On March 9 - 12, 2005, a mass food poisoning caused bybeef offal contaminated by Escherichia coli O157:H7 (E. coliO157) broke out in Kumamoto City. In this outbreak one yakiniku (broiled meat) restaurant was implicated.
The first reported case was a family with three members
who had dinner at the restaurant on the evening of March 12.
One family member developed diarrhea and fever on themorning of March 14. The patient visited a clinic, and E. coli
O157 was isolated from the stool specimen. The Kumamoto
City Health Center then investigated stool specimens fromthe two asymptomatic persons of the family and isolated E.
coli O157 from both of them.
The second case was a family with four members who haddinner at the same restaurant on the evening of March 9. Twoof them developed abdominal pain on the afternoon of March
14. E. coli O157 was isolated from one of them when apatient visited a clinic, and it was reported to the health center
on March 22. Upon investigation, E. coli O157 was isolated
from the other family member who became ill but not fromthe two asymptomatic family members.
The third case was a group with 13 members of the samework place. They had dinner at the same restaurant on theevening of March 11, and five of them developed abdominal
pain and diarrhea in March 13 - 15. E. coli O157 was isolated
from one of them when a patient visited a clinic. It wasreported to the health center on March 24. Upon investigation,
E. coli O157 was isolated from two among the remaining four
symptomatic patients and two among eight asymptomaticmembers.
Upon the report of the second case, the city health center
investigated the broiled meat restaurant. Two specimens ofseasoning, 11 swabs of the kitchen and two stool specimensof cooks were brought into our institute. Pulsed-field gelelectrophoresis (PFGE) conducted in our laboratory revealed
that five isolates tested in the above three cases had a similarpattern.
Hearing the announcement of the above cases by theKumamoto City health authority, a doctor in a clinic reported
the fourth case. Five family members had used the same
restaurant, and one of them had been admitted to a hospitalwith complaints of abdominal pain and hemorrhagic diarrhea.
Thus, in total, four groups were implicated in the mass

No. of persons exposed
Case 1Case 2
Case 3
Case 434135E. coli O157 postitives
symptomatic asymptomatic
123(1)*

2020*Isolation of E. coli O157 was not attempted.

poisoning and seven patients among 24 exposed people
developed symptoms (Table 1). PFGE analysis conducted by
the National Institute of Infectious Diseases revealed nine(including one isolate from the cook) out of 11 isolates showed
an indistinguishable pattern. The other two isolates weredifferent from them by one or two bands. The antibiotic
sensitivity of all of the isolates was identical.
All those implicated in the mass poisoning had consumed
the beef offal. The restaurant served raw offal dipped inseasoning to the clients, and the clients broiled it by themselves. As the patients were treated only on March 9 - 12,during which time the same offal bought in on March 9
was served, the offal was probably responsible for the foodpoisoning. One of the patients was a child who did not eat theoffal. Probably the infection was caused by the contaminatedchopsticks used by the parent to feed her child. One of thecooks who was positive for E. coli O157 was probably notthe infection source because there were no cases later thanMarch 13.
We thank Dr. Hiroshi Yoshikura, Emeritus Researcher of
the National Institute of Infectious Diseases, for advice onpreparing the manuscript.
The present case communicated in Japanese appeared in
the Infectious Agents Surveillance Report (IASR), vol. 26, p.
149-150, 2005.

*Corresponding author: Mailing address: Kumamoto City Environmental Research Institute, Tokorojima 404-1, Ezumachi,
Kumamoto 862-0946, Japan. Tel: +81-96-379-2511, Fax: +8196-379-7783, E-mail: maruzumi.midori@city.kumamoto.lg.jp397