Jpn. J. Infect. Dis., 59, 2006

Laboratory and Epidemiology Communications

Food Poisoning Attributable to Staphylococcus aureus Deficient in
All of the Staphylococcal Enterotoxin Gene So Far Reported
Sanae Kuramoto*, Hiroe Kodama, Keiko Yamada, Itirou Inui, Emiko Kitagawa1, Keiko Kawakami1,Ryouji Satomi1, Akemi Ikawa1, Katsuhiko Omoe2 and Kunihiro Shinagawa2
Ishikawa Prefectural Institute of Public Health and Environmental Science, Ishikawa 920-1154;
1
Ishikawa Prefectural Minamikaga Health Center, Ishikawa 923-8648; and2
Department of Veterinary Medicine, Iwate University, Iwate 020-8550, Japan
Communicated by Haruo Watanabe(Accepted September 6, 2006)
Table 1. Staphylococcal enterotoxin genotypes and coaglase typesof S. aureus

In August 2005, there was an outbreak of food poisoning
in a hotel under the jurisdiction of the Minamikaga HealthCenter, Ishikawa Prefecture, Japan. The health center’s investigation revealed that there were a total of 10 infectedindividuals. Two to 12 h (average 7 h) after the dinner thatwas considered responsible for the food poisoning, thepatients developed diarrhea (100%), abdominal pain (40%)
and nausea or vomiting (30%).
The health center conducted bacteriological investigation
on one specimen of a patient’s vomit, six stool specimens of
the cooks, 11 preserved food specimens, one specimen takenfrom a finger swab of the cooks, and one specimen from arefrigerator handle swab. Staphylococcus aureus was isolated
from the vomit specimen, the three food specimens (sea breamsashimi, frozen boiled crab, pickled radish), the finger swab
and the refrigerator handle swab. The bacterial counts of thethree preserved foods were relatively low, i.e., 50 cfu/g forthe sashimi, 100 cfu/g for the frozen crab, and 50 cfu/g forthe pickled radish. The vomit specimen tested positive forstaphylococcal enterotoxin (SE), but negative for SEA toSED by SET-RPLA (Denka Seiken, Tokyo, Japan). A similar
investigation on the patients’ stool specimens could not bedone as they were all residents of other prefectures.
We conducted coagulase typing and detection of SE gene(s)on 12 isolates, including those from the patient’s vomit andthe sashimi. With the exception of the finger swab isolate,
all other isolates were coagulase type V, and were negativefor SEA to SEE (Table 1). All the examined coagulase V
isolates showed an identical pattern in the pulsed-field gelelectrophoresis (Fig. 1), which suggested that the same bacteria caused the food poisoning.
The isolates were submitted to a multiplex PCR that
detects 17 different SE genes (sea to see, seg to selr) andto search for TSST-1 gene (conducted at Iwate University,Iwate, Japan). All the tests gave negative results. A possibility remains that the bacteria produced an SE(s) other thanSEA to SElR, i.e., a new type of SE, and this possibility iscurrently under investigation.
The possible involvement of S. aureus with an unidentified type SE in food poisoning should be further investigated.
For this purpose, a method for detecting a variety of SEs,No.

SourceEnterotoxin
typeCoaglase
type

1
2
3

Patient’s vomit

non A-E
non A-E
non A-E

VV
V

4

Food (sea bream sashimi)

non A-EV

5
6

Food (frozen boiled crab)

non A-E
non A-E

VV

7

Food (pickled radish)non A-E

V

8
910Finger swab of employee

non A-E
non A-ECVVVII

1112Refrigerator handle swab

non A-E
non A-E

VVFig. 1. PFGE patterns of S. aureus chromosomal DNA digested with SmaI.
1 - 3, patient’s vomit; 4, sliced of raw bream; 5, frozen boiled crab;
6, Japanese radish pickle; 7, finger swab of employee; 8, refrigerator
handle swab; 9, contrast; M, lambda ladder.

including unknown ones, must be developed.
We thank Dr. Hiroshi Yoshikura, Emeritus Researcher of
the National Institute of Infectious Diseases, for advice on
preparing the manuscript.
This article appeared in the Infectious Agents Surveillance
Report (IASR), vol. 27, p. 73-74, 2006 in Japanese.

*Corresponding author: Mailing address: Ishikawa Prefectural
Institute of Public Health and Environmental Science, Taiyougaoka 1-11, Kanazawa, Ishikawa 920-1154, Japan. E-mail:sanakura@pref.ishikawa.jp347