Browsing by Author "Dalusi, Lucy"

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    Genetic Relationship between Clinical and Environmental Vibrio Cholera Isolates in Tanzania: A Comparison Using Repetitive Extragenic Palindromic (REP) and Enterobacterial Repetitive Intergenic Consensus (ERIC) Fingerprinting Approach
    (2015) Dalusi, Lucy; Saarenheimo, Jatta; Lyimo, Thomas J.; Lugomela, Charles
    The bacterium causing cholera, Vibrio cholerae, is a marine organism and coastal waters are important reservoirs of the organism. There are more than 200 serogroups of V. cholerae, of which serogroups O1 and O139 are known to be the causative agent of the cholera. The main virulent factor in V. cholerae is cholera toxin gene (ctx) that is found from the epidemic O1 and O139 strains, but may also be found in some strains other than O1 and O139 (non-O1 and non-O139). In this study, 48 V. cholerae strains isolated from three estuaries of Tanzania and 20 stool isolates were characterized in terms of their serogroups and possession of ctx gene and then compared using two PCR based fingerprinting methods: Enterobacterial repetitive intergenic consensus (ERIC) sequences and repetitive extragenic palindromic (REP) sequences. All the stool isolates and twelve of the environmental isolates belonged to serogroup O1 while the remaining 36 environmental isolates were defined as non-O1/O139. The entire stool isolates and 21 of the environmental isolates had the cholera toxin gene (ctxA). Both ERIC and REP methods gave almost unique fingerprints for each strain and confirmed high genetic heterogeneity among the different cholera strains. Higher similarity was observed in REP-PCR (70-100%) than in ERIC-PCR (62-100%), indicating different discriminative power of these methods. Environmental isolates clustered together with clinical isolates at ≥90% similarity level suggesting their great potential of producing pathogenic strains that may be the causative agents for the frequent observed cholera outbreaks particularly along the coast
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    Genetic Relationship Between Clinical and Environmental Vibrio Cholera Isolates in Tanzania: A Comparison Using Repetitive Extragenic Palindromic (REP) and Enterobacterial Repetitive Intergenic Consensus (ERIC) Fingerprinting Approach
    (Academic Journals, 2015-02) Dalusi, Lucy; Saarenheimo, Jatta; Lyimo, Thomas J.; Lugomela, Charles
    The bacterium causing cholera, Vibrio cholerae, is a marine organism and coastal waters are important reservoirs of the organism. There are more than 200 serogroups of V. cholerae, of which serogroups O1 and O139 are known to be the causative agent of the cholera. The main virulent factor in V. cholerae is cholera toxin gene (ctx) that is found from the epidemic O1 and O139 strains, but may also be found in some strains other than O1 and O139 (non-O1 and non-O139). In this study, 48 V. cholerae strains isolated from three estuaries of Tanzania and 20 stool isolates were characterized in terms of their serogroups and possession of ctx gene and then compared using two PCR based fingerprinting methods: Enterobacterial repetitive intergenic consensus (ERIC) sequences and repetitive extragenic palindromic (REP) sequences. All the stool isolates and twelve of the environmental isolates belonged to serogroup O1 while the remaining 36 environmental isolates were defined as non-O1/O139. The entire stool isolates and 21 of the environmental isolates had the cholera toxin gene (ctxA). Both ERIC and REP methods gave almost unique fingerprints for each strain and confirmed high genetic heterogeneity among the different cholera strains. Higher similarity was observed in REP-PCR (70- 100%) than in ERIC-PCR (62-100%), indicating different discriminative power of these methods. Environmental isolates clustered together with clinical isolates at ≥90% similarity level suggesting their great potential of producing pathogenic strains that may be the causative agents for the frequent observed cholera outbreaks particularly along the coast.
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    Toxigenic Vibrio Cholerae Identified in Estuaries of Tanzania Using PCR Techniques
    (2015) Dalusi, Lucy; Lyimo, Thomas J.; Lugomela, Charles; Hosea, Ken M.; Sjöling, Sara
    The current study assessed the occurrence of the Vibrio cholerae serogroups O1 and O139 in environmental samples along salinity gradients in three selected estuaries of Tanzania both through culture independent methods and by cultured bacteria. Occurrence of V. cholerae was determined by PCR targeting the V. cholerae outer membrane protein gene ompW. Furthermore, the presence of toxigenic strains and serogroups O1 and O139 was determined using multiplex PCR with specific primers targeting the cholera toxin gene subunit A, ctxA, and serotype specific primers, O1-rfb and O139-rfb, respectively. Results showed that V. cholerae occurred in approximately 10% (n = 185) of both the environmental samples and isolated bacteria. Eight of the bacteria isolates (n = 43) were confirmed as serogroup O1 while one belonged to serogroup O139, the first reported identification of this epidemic strain in East African coastal waters. All samples identified as serogroup O1 or O139 and a number of non-O1/O139 strains were ctxA positive. This study provides in situ evidence of the presence of pathogenic V. cholerae O1 and O139 and a number of V. cholerae non-O1/O139 that carry the cholera toxin gene in estuaries along the coast of Tanzania.
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    Toxigenic Vibrio Cholerae Identified in Estuaries of Tanzania Using PCR Techniques
    (oxford university press, 2015-02) Dalusi, Lucy; Lyimo, Thomas J.; Lugomela, Charles; Hosea, Ken M.; Sjöling, Sara
    The current study assessed the occurrence of the Vibrio cholerae serogroups O1 and O139 in environmental samples along salinity gradients in three selected estuaries of Tanzania both through culture independent methods and by cultured bacteria. Occurrence of V. cholerae was determined by PCR targeting the V. cholerae outer membrane protein gene ompW. Furthermore, the presence of toxigenic strains and serogroups O1 and O139 was determined using multiplex PCR with specific primers targeting the cholera toxin gene subunit A, ctxA, and serotype specific primers, O1-rfb and O139-rfb, respectively. Results showed that V. cholerae occurred in approximately 10% (n = 185) of both the environmental samples and isolated bacteria. Eight of the bacteria isolates (n = 43) were confirmed as serogroup O1 while one belonged to serogroup O139, the first reported identification of this epidemic strain in East African coastal waters. All samples identified as serogroup O1 or O139 and a number of non-O1/O139 strains were ctxA positive. This study provides in situ evidence of the presence of pathogenic V. cholerae O1 and O139 and a number of V. cholerae non-O1/O139 that carry the cholera toxin gene in estuaries along the coast of Tanzania. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.