title: Characterization of Shigella sonnei isolates from travel-associated cases in Japan.
abstract: Shigella sonnei infection in industrialized countries is often associated with foreign travel. A total of 195 S. sonnei isolates in Japan, isolated from cases associated with foreign travel, were analysed by biotyping and molecular typing using PFGE and multilocus variable-number tandem-repeat analysis (MLVA); their antimicrobial susceptibilities were also evaluated. The isolates were from 26 countries, most of which were Asian. Molecular typing revealed a correlation among the genotypes, biotypes and their geographical areas of origin. The isolates were classified into two biotypes, a and g. Biotype g isolates (n=178) were further divided into distinct clusters mainly on the basis of their geographical areas of origin by both PFGE and MLVA. Isolates from South Asian countries constituted one of the distinct clusters. Biotype g isolates from countries other than South Asia constituted other distinct clusters. Most of the isolates from other countries and continents, excluding the South Asian countries, were included in one major cluster by PFGE analysis. However, by MLVA, they were further divided into minor subclusters mainly on the basis of their countries of origin. MLVA was also demonstrated to be useful in molecular epidemiological analysis, even when only seven loci were applied, resulting in a high resolution with Simpson's index of diversity (D) of 0.993. A core drug-resistance pattern of streptomycin, sulfisoxazole, tetracycline and trimethoprim-sulfamethoxazole was observed in 108 isolates, irrespective of their geographical areas of origin, but the frequency of resistance to nalidixic acid was high among the South Asian and East Asian isolates. Two isolates from China and India were resistant to cefotaxime and harboured the bla(CTX-M-14) and bla(CTX-M-15) genes, respectively; these isolates were also resistant to nalidixic acid, which is a matter of concern in terms of shigellosis treatment. Use of a combination of methods was found to be effective for epidemiological investigation in the case of S. sonnei infection.
authors: Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Hidemasa
authors: H
authors: Izumiya
authors: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Yuki
authors: Y
authors: Tada
authors: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Kenichiro
authors: K
authors: Ito
authors: Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Tomoko
authors: T
authors: Morita-Ishihara
authors: Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Makoto
authors: M
authors: Ohnishi
authors: Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Jun
authors: J
authors: Terajima
authors: Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Haruo
authors: H
authors: Watanabe
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D024881:Drug Resistance, Bacterial; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D018598:Minisatellite Repeats / Q000235:genetics; D017720:Molecular Epidemiology; D017422:Sequence Analysis, DNA; D012764:Shigella sonnei / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D014195:Travel
chemical_list: D000900:Anti-Bacterial Agents