title: Major tdh(+)Vibrio parahaemolyticus serotype changes temporally in the Bay of Bengal estuary of Bangladesh.
abstract: Vibrio parahaemolyticus is responsible for seafood-related gastroenteritis worldwide. In Bangladesh, diarrhea is endemic and diarrheagenic V. parahaemolyticus serotypes occur naturally in the coastal and estuarine aquatic environment. V. parahaemolyticus strains, isolated from estuarine surface water of the Bay of Bengal villages of Bangladesh during 2006-2008, were tested for the presence of virulence and pandemic-marker genes, serodiversity, and phylogenetic relatedness. PCR analysis of V. parahaemolyticus (n=175) showed 53 (30.3%) strains to possess tdh, the major virulence gene encoding thermostable direct hemolysin. Serotyping results revealed the tdh(+)V. parahaemolyticus strains to belong to 10 different serotypes, of which the O8:K21 (30.2%) and O3:K6 (24.5%) were predominantly non-pandemic and pandemic serotypes, respectively; while O5:K30 and O9:KUT were new. The pandemic markers, orf8 and toxRS(variant), were present only in the pandemic serotype O3:K6 (n=13) and its serovariant O4:K68 (n=2). Temporal distribution of the tdh(+) serotypes revealed the O8:K21 to be predominant in 2006 and 2007, while O3:K6 was the predominant tdh(+) serotype in 2008. Pulsed-field gel electrophoresis (PFGE) of SfiI-digested genomic DNA revealed high genetic diversity among the V. parahaemolyticus strains, while dendrogram constructed with the PFGE patterns formed two major clusters separating the tdh(+) O3:K6 and its pandemic serovariants from the tdh(+) non-pandemic (O8:K21) strains, suggesting different lineages for them. The potential health risk related to the prevalent tdh(+) strains, including the observed temporal change of the predominant tdh(+) serotype, from O8:K21 to the pandemic serotype O3:K6 in estuarine surface waters serving as the major source of drinking water suggests the need for routine environmental monitoring to prevent V. parahaemolyticus infection in Bangladesh.
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Farhana
authors.initials: F
authors.lastname: Akther
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Sucharit Basu
authors.initials: SB
authors.lastname: Neogi
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Wasimul B
authors.initials: WB
authors.lastname: Chowdhury
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Abdus
authors.initials: A
authors.lastname: Sadique
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Atiqul
authors.initials: A
authors.lastname: Islam
authors.affiliation: Department of Microbiology, University of Dhaka, Dhaka 1000, Bangladesh.
authors.forename: Marufa Zerin
authors.initials: MZ
authors.lastname: Akhter
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh.
authors.forename: Fatema-Tuz
authors.initials: FT
authors.lastname: Johura
authors.affiliation: National Institute of Infectious Diseases (NIID), Shinjuku-ku, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohnishi
authors.affiliation: National Institute of Infectious Diseases (NIID), Shinjuku-ku, Tokyo, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Canada.
authors.forename: Yan
authors.initials: Y
authors.lastname: Boucher
authors.affiliation: Infectious Diseases Division, International Center for Diarrheal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh;. Electronic address: munirul@icddrb.org.
authors.forename: Munirul
authors.initials: M
authors.lastname: Alam
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics / Q000302:isolation & purification; D001459:Bangladesh / Q000453:epidemiology; D061006:Bays / Q000382:microbiology*; D003967:Diarrhea / Q000453:epidemiology* / Q000382:microbiology; D016521:Electrophoresis, Gel, Pulsed-Field; D063366:Estuaries; D005759:Gastroenteritis / Q000453:epidemiology* / Q000382:microbiology; D014644:Genetic Variation; D006460:Hemolysin Proteins / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D010802:Phylogeny; D012424:Rural Population; D012703:Serotyping; D014735:Vibrio Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics / Q000302:isolation & purification
chemical_list: D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D037521:Virulence Factors; C068489:thermostable direct hemolysin
keywords: O3:K6; O8:K21; Pandemic; Serotype; V. parahaemolyticus; tdh