title: Lack of polymorphism in a Vibrio cholerae O139-specific DNA region encoding the somatic antigen in strains isolated during 1993-1998.
abstract: Vibrio cholerae O139 Bengal emerged as a second aetiologic agent of cholera in South Asia in late 1992. This new serogroup arose from a Vibrio cholerae O1 strain by deletion of the chromosomal region encoding O1 specificity and acquisition of a novel 35-kb region encoding the O139 specificity. Previous studies indicated significant phenotypic and genotypic changes in O139 isolates over the years since its first appearance. This prompted us to study possible polymorphism in the 35-kb novel region encoding the O139 specificity. A total of 17 V. cholerae O139 isolates originating from different countries and years in South Asia and China, and a single unrelated V. cholerae O139 isolate from Argentina were studied. The 35-kb chromosomal region was amplified as two fragments of 12 and 23 kb in an extended PCR from all isolates. These amplicons were then treated separately with seven different restriction enzymes and separated by agarose gel electrophoresis. The South Asian and Chinese isolates gave identical patterns for the same enzymes, but different patterns for different enzymes, thus exhibiting no polymorphism in the 35-kb region. However, the Argentine isolate gave distinct patterns for most of the enzymes confirming its different origin. This data indicated that the portion of the chromosome encoding the O139 antigen specificity is highly conserved. As found in previous studies, the early O139 isolates were resistant to trimethoprim-sulfamethoxazole (TMP-SMX) and vibriostatic compound, O/129, and CAMP- haemolysin positive. The isolates of later years diverged exhibiting different patterns by pulsed-field gel electrophoresis (PFGE), and becoming susceptible to TMP-SMX and O/129, and CAMP-haemolysin negative.
authors.affiliation: Karolinska Institute, Department of Microbiology, Pathology and Immunology, Division of Clinical Bacteriology, Huddinge University Hospital, Stockholm, Sweden.
authors.forename: Susanna
authors.initials: S
authors.lastname: Falklind-Jerkérus
authors.forename: M John
authors.initials: MJ
authors.lastname: Albert
authors.forename: Andrej
authors.initials: A
authors.lastname: Weintraub
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001118:Argentina; D001208:Asia; D002681:China; D002771:Cholera / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D006461:Hemolysis; D006801:Humans; D019081:O Antigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D011621:Pteridines / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D041242:Vibrio cholerae O139 / Q000145:classification / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D019081:O Antigens; D011621:Pteridines; C021594:O 129; D015662:Trimethoprim, Sulfamethoxazole Drug Combination