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Molecular characterisation of Vibrio choleraeO1 strains carrying an SXT/R391-like element from cholera outbreaks in Kenya: 1994-2007

Authors
  • Kiiru, John N1, 2, 3
  • Saidi, Suleiman M1
  • Goddeeris, Bruno M2, 4
  • Wamae, Njeri C1
  • Butaye, Patrick3, 5
  • Kariuki, Samuel M1
  • 1 Kenya Medical Research Institute, Centre for Microbiology Research, Nairobi, Kenya , Nairobi
  • 2 Katholieke Universiteit Leuven, Department of Biosystems, Faculty of Bio-Science Engineering, Kasteelpark Arenberg 30, Heverlee, B-3001, Belgium , Heverlee
  • 3 Veterinary and Agrochemical Research Centre, Groeselenberg 99, Ukkel, B-1180, Belgium , Ukkel
  • 4 University of Ghent, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Salisburylaan 133, Merelbeke, 9820, Belgium , Merelbeke
  • 5 Faculty of Veterinary Medicine University of Ghent Salisburylaan 133, Department of Pathology, Bacteriology and Poultry Diseases, Merelbeke, 9820, Belgium , Merelbeke
Type
Published Article
Journal
BMC Microbiology
Publisher
Springer (Biomed Central Ltd.)
Publication Date
Dec 29, 2009
Volume
9
Issue
1
Identifiers
DOI: 10.1186/1471-2180-9-275
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundOver the last decade, cholera outbreaks in parts of Kenya have become common. Although a number of recent studies describe the epidemiology of cholera in Kenya, there is paucity of information concerning the diversity and occurrence of mobile genetic elements in Vibrio cholerae strains implicated in these outbreaks. A total of 65 Vibrio cholerae O1 El Tor serotype Inaba isolated between 1994 and 2007 from various outbreaks in Kenya were investigated for mobile genetic elements including integrons, transposons, the integrating conjugative elements (ICEs), conjugative plasmids and for their genotypic relatedness.ResultsAll the strains were haemolytic on 5% sheep blood and positive for the Vibrio cholerae El Tor-specific haemolysin toxin gene (hylA) by PCR. They all contained strB, sulII, floR and the dfrA1 genes encoding resistance to streptomycin, sulfamethoxazole, chloramphenicol and trimethoprim respectively. These genes, together with an ICE belonging to the SXT/R391 family were transferable to the rifampicin-resistant E. coli C600 en bloc. All the strains were negative for integron class 1, 2 and 3 and for transposase gene of transposon Tn7 but were positive for integron class 4 and the trpM gene of transposon Tn21. No plasmids were isolated from any of the 65 strains. All the strains were also positive for all V. cholera El Tor pathogenic genes except the NAG- specific heat-stable toxin (st) gene. None of the strains were positive for virulence genes associated with the V. cholerae classical biotype. All the strains were positive for El Tor-specific CTXphi bacteriophage rstrR repressor gene (CTXETΦ) but negative for the Classical, Calcutta, and the Environmental repressor types. Pulse Field Gel Electrophoresis (PFGE) showed that regardless of the year of isolation, all the strains bearing the SXT element were clonally related.ConclusionsThis study demonstrates that the V. cholerae O1 strains carrying an SXT/R391-like element implicated in recent cholera outbreaks in Kenya has not changed significantly between 1994 and 2007 and are clonally related.

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