Jpn. J. Infect. Dis., 52 (6), 246-247, 1999

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Laboratory and Epidemiology Communications

Emergence and Prevalence of a Novel Vibrio parahaemolyticus O3:K6 Clone in Japan

Eiji Arakawa, Toshiyuki Murase‚P, Toshio Shimada, Tadayuki Okitsu‚P, Shiro Yamai‚P and Haruo Watanabe*

Department of Bacteriology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo 162-8640 and 1Department of Bacteriology and Pathology, Kanagawa Prefectural Public Health Laboratory, Asahi, Yokohama, Kanagawa 241-0815

Communicated by Hiroshi Yoshikura

(Accepted January 5, 2000)


Vibrio parahaemolyticus was at the top of the list of pathogens isolated from patients with food-born diseases in 1998 in Japan. One of the dominant serotypes among the isolates was O3:K6. This serotype has been increasing since 1996 (1). Here we examined clonality of the 03:K6 isolates by using pulsed-field gel electrophoresis (PFGE) as previously described (2). We used a total of 86 V. parahaemolyticus O3:K6 isolates discovered between 1962 and 1999 (Table). These consisted of one isolate obtained in 1962; 5 isolates obtained from patients in 1998 in the USA (kindly provided from CDC, USA); 2 isolates from patients in 1998 in Tokyo; 8 isolates from patients, food or the environment in 1997-1998 in Aomori Prefecture; 61 isolates from patients, food or the environment in 1981-1998 in Kanagawa Prefecture; 6 isolates from patients in 1997-1998 at Narita Airport Quarantine Station; and 3 isolates from patients in 1999 in Thailand (kindly provided from the National Institute of Health in Thailand). Fifteen isolates with other serotypes, including O3:K48, O3:K56, O4:K8, O4:K12, and O4:K68, were included in the analysis. In addition to PFGE analysis, PCR detection of tdh (thermostable direct hemolysin) and trh (tdh-related hemolysin) genes and urease test were performed.

PFGE patterns of NotI- or SfiI-digests of DNAs derived from the O3:K6 isolates could be classified into 10 distinct groups, designated as A to J (Fig. and Table). All of the tdh+, trh-, and urease negative isolates obtained later than 1996 (65 strains including isolates from Thailand and the USA) constituted group A, while strains with the same phenotype obtained in 1981 constituted group B (Table). Though differences were found between the PFGE pattern of each group in 03:K6 and other serotypes, recent isolates of the O4:K68 serotype were very similar to recent isolates of the O3:K6 serotype (compare the lane of O4:K68 and that of group A of O3:K6 in Fig.).

We showed here that recent V. parahaemolyticus O3:K6 isolates in Japan had a PFGE pattern distinct from that prevalent in previous isolates. In addition, we identified a PFGE pattern indistinguishable from those of recent Japanese isolates in the Thai and US isolates. The same PFGE pattern was reported in India, Southeast Asia, and the USA (3-6). Taken together, these data may suggest the emergence of a new V. parahaemolyticus O3:K6 clone that is spreading worldwide and already affecting Japan.

We thank the Aomori Prefectural Institute of Public Health and Environment, the Tokyo Metropolitan Research Laboratory and Public Health and the Narita Airport Quarantine Station for providing strains.
This study was supported by a grant from the Ministry of Health and Welfare of Japan.

REFERENCES

  1. National Institute of Infectious Diseases and Infectious Diseases Division, Ministry of Health and Welfare (1999): Vibrio parahaemolyticus, Japan, 1996-1998. Infect. Agents Surveillance Rep., 20, 159'-160'.
  2. Arakawa, E., Murase, T., Matsushita, S., Shimada, T., Yamai, S., Ito, T. and Watanabe, H. (2000): Pulsed-field gel electrophoresis-based molecular comparison of Vibrio cholerae O1 isolates between domestic and imported cases in Japan in 1997. J.Clin. Microbiol., 38, 424-426.
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  5. Centers for Disease Control and Prevention (1998): Outbreak of Vibrio parahaemolyticus infections associated with eating oysters - Pacific Northwest, 1997. Morbid. Mortal. Wkly. Rep., 47, 457-62.
  6. Centers for Disease Control and Prevention (1999): Outbreak of Vibrio parahaemolyticus infections associated with eating raw oysters and clams harvested from Long Island Sound - Connecticut, New Jersey, and New York, 1998. Morbid. Mortal. Wkly. Rep., 48, 48-51.

*Corresponding author: E-mail: haruwata@nih.go.jp

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