Multilocus variable-number tandem repeat analysis of Vibrio cholerae O1 El Tor strains harbouring classical toxin B

International Vaccine Institute, Seoul, Republic of Korea.
Journal of Medical Microbiology (Impact Factor: 2.27). 03/2010; 59(Pt 7):763-9. DOI: 10.1099/jmm.0.017939-0
Source: PubMed

ABSTRACT Atypical Vibrio cholerae O1 strains - hybrid strains (strains that cannot be classified either as El Tor or classical biotype) and altered strains (El Tor biotype strains that produce classical cholera toxin) - are currently prevalent in Asia and Africa. A total of 74 hybrid and altered strains that harboured classical cholera toxin were investigated by multilocus variable-number tandem repeat analysis (MLVA). The results showed that the hybrid/altered strains could be categorized into three groups and that they were distant from the El Tor strain responsible for the seventh cholera pandemic. Hybrid/altered strains with a tandem repeat of the classical CTX prophage on the small chromosome were divided into two MLVA groups (group I: Mozambique/Bangladesh group; group III: Vietnam group), and altered strains with the RS1-CTX prophage containing the El Tor type rstR and classical ctxB on the large chromosome were placed in two MLVA groups (group II: India/Bangladesh group; group III: India/Vietnam group).

Download full-text


Available from: Mohammad Ansaruzzaman, Aug 17, 2015
  • Source
    • "Using multi-locus variable number tandem repeat analysis, a recent study demonstrated that altered strains from Vietnam are distant from the El Tor prototype strain responsible for the seventh cholera pandemic (Choi et al., 2010). In spite of the minor divergences observed in the present study, the Vietnamese V. cholerae O1 strains with the RS1–CTX prophage (El Tor type rstR and classical ctxB) array on the large chromosome is likely to be more closely related to V. cholerae O1 El Tor variant strains currently circulating in Bangladesh (Nair et al., 2006), India (Goel et al., 2010) and Thailand (Okada et al., 2010). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Since 2007, there has been a re-emergence of cholera outbreaks in northern Vietnam. To understand the molecular epidemiological relatedness and determine the antibiotic susceptibility profiles of responsible V. cholerae O1 outbreak strains, a representative collection of 100 V. cholerae O1 strains was characterized. V. cholerae O1 strains isolated from diarrhoeal patients in northern Vietnam between 2007 and 2010 were investigated for antibiotic susceptibility and characterized by using phenotypic and genotypic tests, including PFGE analysis. Ten clinical V. cholerae O1 isolates from Bangladesh and Zimbabwe were included for comparison. The results revealed that all isolates were resistant to co-trimoxazole and nalidixic acid, 29 % were resistant to tetracycline and 1 % were resistant to azithromycin. All strains were susceptible to ampicillin-sulbactam, doxycycline, chloramphenicol and ciprofloxacin and 95 % were susceptible to azithromycin. MIC values did show reduced susceptibility to fluoroquinolones and 63 % of the strains were intermediately resistant to tetracycline. The isolates expressed phenotypic traits of both serogroup O1 Ogawa and El Tor and harboured an rstR El Tor and ctxB classical biotype. Among the outbreak isolates, only a single PFGE pattern was observed throughout the study period. This study shows that multi-drug resistant V. cholerae altered El Tor producing classical CT strains are now predominant in northern Vietnam.
    Journal of Medical Microbiology 03/2012; 61(Pt 3):431-7. DOI:10.1099/jmm.0.034744-0 · 2.27 Impact Factor
  • Source
    • "Atypical El Tor strains have been classified into two different groups on the basis of genetic structures of the CTX prophage and RS1 element on each chromosome (Lee et al., 2009; Nguyen et al., 2009). Group 1 strains harbor a tandem repeat of the classical CTX prophage on the small chromosome and Group II strains contain the RS1 and CTX prophage with El Tor type rstR and classical ctxB on the large chromosome (Lee et al., 2009; Choi et al., 2010). All the strains used in this study belonged to Group II strains. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Thirty-four Vibrio cholerae isolates collected from a cholera outbreak in Hyderabad, South India were found to belong to serogroup Ol biotype El Tor serotype Ogawa. The genotype of all the isolates was confirmed by PCR assays. All the isolates were found PCR positive for ctxAB, ompW, rflOl, rtxC, and tcpA genes. All the isolates but one harboured rstR ( El Tor ) allele. However, one isolate carried both rstR ( EL Tor ) as well as rstR ( Classical ) alleles. Cholera toxin (ctxB) genotyping of the isolates confirmed the presence of altered cholera toxin B of classical biotype in all the isolates. All the isolates except VCH35 harboured an RS1-CTX prophage array on the large chromosome. The isolate VCH35 contained a tandem repeat of classical CTX prophage on the small chromosome. The clonal relationship among the V. cholerae isolates as carried out by enterobacterial repetitive intergenic consensus sequences PCR, BOX PCR and randomly amplified polymorphic DNA, uniformly showed a genetic relationship among the outbreak isolates. The results of this study suggest that altered El Tor biotype V. cholerae with the classical cholera toxin gene are involved in cholera outbreaks in India.
    The Journal of Microbiology 04/2011; 49(2):280-4. DOI:10.1007/s12275-011-0317-9 · 1.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The genetic relatedness of Vibrio cholerae O1/O139 isolates obtained from 100 patients and 146 of their household contacts in Dhaka, Bangladesh, between 2002 and 2005 was assessed by multilocus variable-number tandem-repeat analysis. Isolate genotypes were analyzed at five loci containing tandem repeats. Across the population, as well as within households, isolates with identical genotypes were clustered in time. Isolates from individuals within the same household were more likely to have similar or identical genotypes than were isolates from different households, but even within a household, isolates from different individuals often had different genotypes. When household contacts were sampled regularly for 3 weeks after the illness of the household index patient, isolates with genotypes related to the index patient appeared in contacts, on average, approximately 3 days after the index patient, while isolates with unrelated genotypes appeared in contacts approximately 6 days after. Limited data revealed that multiple isolates from the same individual collected within days of each other or even from a single stool sample may have identical, similar, or unrelated genotypes as well. Our results demonstrate that genetically related V. cholerae strains cluster in local outbreaks but also suggest that multiple distinct strains of V. cholerae O1 may circulate simultaneously within a household.
    Journal of bacteriology 09/2010; 192(17):4367-76. DOI:10.1128/JB.00698-10 · 2.69 Impact Factor
Show more