Virulence Factors and Genotyping of Shigella sonnei Isolated from Patients / 대한진단검사의학회지

ABSTRACT

BACKGROUND: Nineteen strains of Shigella sonnei isolated from the patients were examined regarding their biochemical characterization, serotype, and antibiotics resistance, and then analyzed for plasmid DNA profile. METHODS: Strains were tested for possession of set1A, set1B, sen, ipaH, ial, stx and invE genes using the polymerase chain reaction (PCR) method and were analyzed using the pulsed-field gel electrophoresis (PFGE) pattern against 7 outbreak isolates (10 strains). RESULTS: These strains had the typical biochemical characterization of S. sonnei with positive ornithine decarboxylase and -galactosidase activity, but were negative in mannitol fermentation. Serotype were identified as the I phase in 13 strains (68.0%) and the II phase in 6 strains (32.0%). All strains were resistant to erythromycin, vancomycin, tetracycline, and penicillin. The antibiogram type showed 4 groups from I to IV. The strains showed 8 types of plasmid profiles and were designated as P1 to P8. By the PCR, the ipaH gene and the set1B gene were detected from all of the 16 strains. The invE was detected from 9 strains (56.3%), and the sen gene was detected from 5 strains. All strains were negative for the Stx and the set1A gene. High-molecular-weight genomic DNA was prepared from 7 outbreak isolates (10 strains) and digested with the restriction endonuclease XbaI. Restriction fragment patterns of chromosomal DNA were demonstrated by PFGE. XbaI produced about 23 fragments in all strains with the their size ranged from 40 to 680 kb. Ten strains could be differentiated to 3 patterns by chromosomal DNA fingerprint. CONCLUSIONS: All of the Shigella sonnei strains that were isolated from Busan Province showed similar chromosomal DNA fragment patterns, while the Japanese differed in chromosomal DNA fingerprint pattern. PFGE is useful for the epidemiological study of Shigella sonnei associated endemic diarrhea.