Evolution of Seventh Cholera Pandemic and Origin of 1991 Epidemic, Latin America

Thirty single-nucleotide polymorphisms were used to track the spread of the seventh pandemic caused by Vibrio cholerae. Isolates from the 1991 epidemic in Latin America shared a profile with 1970s isolates from Africa, suggesting a possible origin in Africa. Data also showed that the observed genotypes spread easily and widely

Microbes Isolated from Landfill Soil Utilize Polyethylene Terephthalate (PET) as Their Sole Source of Carbon: An Unexplored Possibility of Bioremediation in Bangladesh

Plastic products are so extensively used that they continue to strain the already overburdened waste management system and, inevitably, the global climate. Biodegradation is a sustainable remedy. Here, we report a few microorganisms isolated from landfill soil near Dhaka that thrive especially on polyethylene terephthalate (PET) polymers. Soil samples were subjected to three enrichment cycles that contained no carbon except PET. Pure isolates were recovered and incubated on minimal agar containing PET as the sole carbon. A morphological examination was carried out. Potential PET-degrading enzyme sequences from the isolates and other microalgae were analyzed for homology using BLASTP and TBLASTN, and multiple sequence alignment (MSA) was performed to assess conserved domains. Six isolates were obtained. Two isolates grew around the PET film but did not grow sufficiently in other areas of the minimal agar. Two other isolates with greenish pigmentation flourished around the PET film as well as on other areas of the agar. One of the green cells resembled Aphanocapsa, with irregular shapes and occasionally brown dense bodies, while the others looked round like Microcystis. Homology analysis revealed the hypothetical PETases in green cells contained the highly conserved catalytic triad (Ser-His-Asp) at the active site, as always found in alpha-beta hydrolase fold containing enzymes. Microbes isolated from two landfill sites in the vicinity of Dhaka have been adapted to utilize PET as a carbon source. In the future, sequencing and further characterization would be necessary to validate the findings. Microalgal systems demand increased focus, given their potential to offer valuable resources for bioremediation

Isolation of Vibrio cholerae O1 strains similar to pre-seventh pandemic EI Tor strains during an outbreak of gastrointestinal disease in an island resort of Fiji

Five strains of Vibrio cholerae O1, one each from an Australian and a New Zealand tourist with gastrointestinal illness returning from an island resort in Fiji and the remaining three from water sources located in the same resort, were extensively characterized. Conventional phenotypic traits that are used for biotyping of O1 V. cholerae categorized all five strains as belonging to the El Tor biotype. Genetic screening of 11 regions that are associated with virulence in V. cholerae showed variable results. The absence of genes comprising Vibrio seventh pandemic island-I (VSP-I) and VSP-II in all the strains indicated that these strains were very similar to the pre-seventh pandemic V. cholerae O1 El Tor strains. The ctxAB genes were absent in all strains whereas orfU and zot were present in four strains, indicating that the strains were non-toxigenic. Four strains carried a truncated CTX prophage. Although epidemiological and molecular studies suggested that these strains did not cause cholera amongst tourists at the resort, their similarity to pre-seventh pandemic strains, their prior association with gastrointestinal illness and their presence in the island resort setting warrant more attention

Genetic characteristics of matlab variants of vibrio cholerae O1 that are hybrids between classical and El Tor biotypes

The Matlab variants of Vibrio cholerae O1, defined as hybrids between the classical and El Tor biotypes, were first isolated from hospitalized patients with acute secretory diarrhoea in Matlab, a rural area of Bangladesh. These variants could not be categorized as classical or El Tor biotypes by phenotypic and genotypic tests, and had representative traits of both the biotypes. A number of virulence-associated genes and/or gene clusters were screened by PCR and DNA sequencing. El Tor-specific gene clusters, Vibrio seventh-pandemic islands (VSP)-I and -II and repeat toxin (RTX) were present in the genome of these variants, indicating their El Tor lineage, whereas the nucleotide-sequence-derived CtxB amino acid sequence of these strains grouped them under the classical biotype. Matlab variants possessed all the necessary genes to initiate pandemics. The genetic relatedness of Matlab variants to the V. cholerae strains recently isolated in Mozambique is another important observation of this study, which underscores the epidemiological significance of Matlab variants

Changing genotypes of cholera toxin (CT) of vibrio cholerae O139 in Bangladesh and description of three new CT genotypes

We determined the genotype of cholera toxin by amplifying and sequencing the B-subunit in a sequential collection of 90 strains of Vibrio cholerae O139 isolated over the past 13 years since its first description in 1992. Representative strains isolated during 1993-1997 harboured ctxB of El Tor type (genotype 3). Twenty-six strains isolated during 1999, 2001, 2005 and three strains isolated in 1998, 2000 and 2002 were identified to belong to new ctxB genotypes 4 and 5, respectively. Genotype 5 was similar to genotype 1 except at position 28 (D→A). The genotype 6 was similar to genotype 4 except at position 34 (H→P). The implication of switch in terms of function of the toxin and its impact on human disease is unclear. How this change has influenced their prevalence relative to that of V. cholerae O1 in human infection is also not clear. The other common virulence gene clusters including the Vibrio pathogenicity island-1, Vibrio seventh pandemic island (VSP)-I and VSP-II of V. cholerae O139 did not show any remarkable difference from that of the O1 El Tor strains. Overall, the majority of the O139 strains tested in this study were similar to the El Tor strains but had altered ctxB genotype. This change and the impact that it causes to the epidemiology of cholera caused by O139 should be closely monitored

Isolation of vibrio cholerae O1 strains similar to pre-seventh pandemic El Tor strains during an outbreak of gastrointestinal disease in an island resort in Fiji

Five strains of Vibrio cholerae O1, one each from an Australian and a New Zealand tourist with gastrointestinal illness returning from an island resort in Fiji and the remaining three from water sources located in the same resort, were extensively characterized. Conventional phenotypic traits that are used for biotyping of O1 V. cholerae categorized all five strains as belonging to the El Tor biotype. Genetic screening of 11 regions that are associated with virulence in V. cholerae showed variable results. The absence of genes comprising Vibrio seventh pandemic island-I (VSP-I) and VSP-II in all the strains indicated that these strains were very similar to the pre-seventh pandemic V. cholerae O1 El Tor strains. The ctxAB genes were absent in all strains whereas orfU and zot were present in four strains, indicating that the strains were non-toxigenic. Four strains carried a truncated CTX prophage. Although epidemiological and molecular studies suggested that these strains did not cause cholera amongst tourists at the resort, their similarity to pre-seventh pandemic strains, their prior association with gastrointestinal illness and their presence in the island resort setting warrant more attention