Biochemical, Serological and Virulence-associated Characteristics of Yersinia enterocolitica Isolated in Korea

Park, Joo Youn; Park, Yong Ha; Yoo, Han Sang

Abstract

BACKGROUND
Yersinia enterocolitica is an inhabitant in lower intestinal tract of many domestic and wild animals as well as in nature. Of the several forms of diseases by Y. enterocolitica, acute enteritis, especially in young children, is most common. Infection of the bacteria is usually occurred through fecal-oral route by contaminated foods or water, especially mountainspring water. Therefore, we isolated Y. enterocolitica from feces of pigs and mountainspring water and investigated the biochemical, serological, genetical and virulence-associated characteristics of the bacteria for the epidemiological analysis.
METHODS
Fifty-one strains of Y. enterocolitica were isolated from the samples and identified by biochemical tests and VITEK system. We performed antimicrobial susceptibility test, in vitro virulence-associated characteristics, biotyping, serotyping, and PCR-ribotyping and compared the methods, such as biotype, serotype and PCR-ribotyping, to differentiate the isolates.
RESULTS
Biochemical properties of the isolates were very similar to those of reference strains. They were susceptible to chloramphenicol, tetracycline, norfloxacin, but resistant to bacitracin, ampicillin in antimicrobial susceptibility test. In vitro virulence-associated tests, the positive strains were 27 isolates (52.9%) in CRMOX+, 10 isolates (19.6%) in CV+, 30 isolates (58.8%) in CD+, 20 isolates (39.2%) in esculin+ and 20 isolates in salicin+ (39.2%). Thirty-one strains of 51 isolates (61%) harbored about 70 kb plasmid presumably associated with virulence factor. Biotypes and serotypes of the strains were 3B, 3A, 4 and O:3, O:13, O:16 in order, respectively. Type I having 700 and 800 bps products was the most common type of PCR-ribotypes.
CONCLUSION
Biochemical properties, biotypes and serotypes of the isolates were similar with previously reports in Korea. PCR-ribotyping, a genetical method, could be a more effective tool for differentiating isolates of Yersinia enterocolitica than conventional methods such as serotype, biotype.