Two hundreds and sixty-five strains of Shigella isolated in Korea from 1983 to 1992 were epidemiologically analyzed for plasmid profile, antibiogram, and biotype of isolates, and incompatibilty group(Inc), and restriction endonuclease fragment
pattern
type of conjugative R plasmids.
1. One hundred and seventeen strains(58%) of 203 S. flexneri and 52(95%) of 55 S. sonnei were resistant to trimethoprim(Tp). The most prevalent resistance patterns of both isolates and their conjugative R plasmids were chloramphenicol(Cm),
tetracycline(Tc), streptomycin, sulfisoxazole(Su), ampicillin, Tp in S. flexneri and CmTcSmSuTp in S. sonnei.
2. Most isolates harbored plasmids, up to maximun eight within one strain, and 23 and 10 plasmid pattern types observed in S. flexneri and S. sonnei respectively by using small plasmids of molecular size less than 10meagdatons(MDa).
3. Tp-resistant R plasmids ranged from 88 to 44Mda and most of them were classified to IncFII plasmid ranging from 76 to 57Mda. IncFI, IncB or untypable R plasmids were detected in strains showing various resistance patterns.
4. The restriction endonuclease analysis of conjugative R plasmids belonged to IncFII showed various fragment pattern types, but many common fragments were found among them. By hybridization analysis, all R plasmids encoding resistance to Cm, Tc,
Sm Su,
and Tp regardless of serotype responded specifically on 4.4kilobase fragments to typeⅡdihydrofolate reductase probe.
These findings suggest that plasmid profile analysis are usuful as an epidemiological tool of for Shigella isolates, and flexneri and S. sonnei isolated in Korea were derived from multiple clone but IncFII R plasmids found in most strains of both
serotypes were probably originated from similar sources.
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