[Analysis of thermostable direct hemolysin-producing Vibrio parahaemolyticus by pulsed-field gel electrophoresis].
OBJECTIVE
We investigated the source of thermostable direct hemolysin-producing Vibrio parahaemolticus infection (positive strains) that causes Vibrio parahaemolticus food poisoning.


METHODS
We investigated the coincidence rate of serotypes isolated from samples of sea water used to store clams in 1998 in Shizuoka Prefecture, and those isolated from patients who developed symptoms of food poisoning in the same year. Furthermore, using isolated types 03:K6 and 04:K68, We treated the chromosomal DNA with a restriction endonuclease Sfi I and compared the digestion patterns by pulsed-field gel electrophoresis (PFGE).


RESULTS
(1) Of 225 samples of sea water used to store clams, the thermostable direct hemolysin gene was detected in 23 samples by the PCR method. Among these 23 samples, 10 positive strains were detected in five samples. The serotypes of these productive strains were 03:K6 (four isolates), 03:K37 (two isolates), 04:K8 (one isolate), 04:K9 (two isolates) and 04:K68 (one isolate). (2) The five serotypes isolated from the sea water samples were consistent with those of 17 of 17 cases (100%) of which serotypes could be confirmed by this institute and 94 of 100 strains (94%) isolated in a large scale outbreak of food poisoning that occurred in the same year. (3) Using types 03:K6 and 04:K68 isolated from sea water samples and patients, chromosomal DNA were compared among the isolates by PFGE. As a result, of 28 isolates examined, 26 isolates showed a similar electrophoretic migration pattern between the sources and serotypes.


CONCLUSIONS
The etiologic strains for Vibrio parahaemolyticus food poisoning appear to have been derived from the environment. Regarding the findings that types 03:K6 and 04:K68 showed a similar electrophoretic migration pattern, these types can be considered to belong to the same PFGE type.
Kubota
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Shizuoka Prefectural Institute of Public Health and Enviromental Science.
D016521:Electrophoresis, Gel, Pulsed-Field; D005517:Foodborne Diseases / Q000382:microbiology*; D006460:Hemolysin Proteins / Q000096:biosynthesis* / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D016133:Polymerase Chain Reaction; D012623:Seawater; D012703:Serotyping; D014735:Vibrio Infections / Q000382:microbiology*; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000302:isolation & purification*
D006460:Hemolysin Proteins