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Applied and Environmental Microbiology, October 2009, p. 6268-6274, Vol. 75, No. 19
0099-2240/09/$08.00+0 doi:10.1128/AEM.00266-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Serogroup, Virulence, and Genetic Traits of Vibrio parahaemolyticus in the Estuarine Ecosystem of Bangladesh
Munirul Alam,1
Wasimul B. Chowdhury,1
N. A. Bhuiyan,1
Atiqul Islam,1
Nur A. Hasan,1
G. Balakrish Nair,1,2
H. Watanabe,3
A. K. Siddique,1
Anwar Huq,4
R. Bradley Sack,5
M. Z. Akhter,6
Christopher J. Grim,4,8
K.-M. Kam,7
C. K. Y. Luey,7
Hubert P. Endtz,1
Alejandro Cravioto,1 and
Rita R. Colwell4,5,8*
International Center for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Mohakhali, Dhaka 1212, Bangladesh,1 National Institute of Cholera and Enteric Diseases, Kolkata, India,2 Department of Bacteriology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan,3 Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland,4 Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland,5 Department of Microbiology, University of Dhaka, Dhaka 1000, Bangladesh,6 Public Health Laboratory Center, Hong Kong,7 Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland8
Received 3 February 2009/ Accepted 17 July 2009
Forty-two strains of Vibrio parahaemolyticus were isolated from Bay of Bengal estuaries and, with two clinical strains, analyzed for virulence, phenotypic, and molecular traits. Serological analysis indicated O8, O3, O1, and K21 to be the major O and K serogroups, respectively, and O8:K21, O1:KUT, and O3:KUT to be predominant. The K antigen(s) was untypeable, and pandemic serogroup O3:K6 was not detected. The presence of genes toxR and tlh were confirmed by PCR in all but two strains, which also lacked toxR. A total of 18 (41%) strains possessed the virulence gene encoding thermostable direct hemolysin (TDH), and one had the TDH-related hemolysin (trh) gene, but not tdh. Ten (23%) strains exhibited Kanagawa phenomenon that surrogates virulence, of which six, including the two clinical strains, possessed tdh. Of the 18 tdh-positive strains, 17 (94%), including the two clinical strains, had the seromarker O8:K21, one was O9:KUT, and the single trh-positive strain was O1:KUT. None had the group-specific or ORF8 pandemic marker gene. DNA fingerprinting employing pulsed-field gel electrophoresis (PFGE) of SfiI-digested DNA and cluster analysis showed divergence among the strains. Dendrograms constructed using PFGE (SfiI) images from a soft database, including those of pandemic and nonpandemic strains of diverse geographic origin, however, showed that local strains formed a cluster, i.e., "clonal cluster," as did pandemic strains of diverse origin. The demonstrated prevalence of tdh-positive and diarrheagenic serogroup O8:K21 strains in coastal villages of Bangladesh indicates a significant human health risk for inhabitants.
* Corresponding author. Mailing address: Center of Bioinformatics and Computational Biology, 3103 Biomolecular Sciences Building #296, University of Maryland at College Park, College Park, MD 20742. Phone: (301) 405-9550. Fax: (301) 314-6654. E-mail: rcolwell{at}umiacs.umd.edu
Published ahead of print on 14 August 2009.
Applied and Environmental Microbiology, October 2009, p. 6268-6274, Vol. 75, No. 19
0099-2240/09/$08.00+0 doi:10.1128/AEM.00266-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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