Draft Genome Sequence of Environmental Bacterium Vibrio vulnificus CladeA-yb158

We report the genome sequence of the environmental Vibrio vulnificus biotype 1_cladeA. This draft genome of the CladeA-yb158 strain, isolated in Israel, represents this newly emerged clonal group that contains both clinical and environmental strains

Epidemiologic Study of Vibrio vulnificus Infections by Using Variable Number Tandem Repeats

A 3-year environmental and clinical Vibrio vulnificus survey using simple-sequence repeats typing shows that V. vulnificus biotype 3 constitutes ≈21% of the bacterium population in tested aquaculture ponds as opposed to ≈86% of clinical cases. Simple-sequence repeats proved to be a useful epidemiologic tool, providing information on the environmental source of the pathogen

Genome-Wide SNP-genotyping array to study the evolution of the human pathogen Vibrio vulnificus Biotype 3

Vibrio vulnificus is an aquatic bacterium and an important human pathogen. Strains Of V. vulnificus are classified into three different biotypes. The newly emerged biotype 3 has been found to be clonal and restricted to Israel. In the family Vibrionaceae , horizontal gene transfer is the main mechanism responsible for the emergence of new pathogen groups. To better understand the evolution of the bacterium, and in particular to trace the evolution of biotype 3, we performed genome-wide SNP genotyping of 254 clinical and environmental V. vulnificus isolates with worldwide distribution recovered over a 30-year period, representing all phylogeny groups. A custom single-nucleotide polymorphism (SNP) array implemented on the Illumina GoldenGate platform was developed based on 570 SNPs randomly distributed throughout the genome. In general, the genotyping results divided the V. vulnificus species into three main phylogenetic lineages and an additional subgroup, clade B, consisting of environmental and clinical isolates from Israel. Data analysis suggested that 69% of biotype 3 SNPs are similar to SNPs from clade B, indicating that biotype 3 and clade B have a common ancestor. The rest of the biotype 3 SNPs were scattered along the biotype 3 genome, probably representing multiple chromosomal segments that may have been horizontally inserted into the clade B recipient core genome from other phylogroups or bacterial species sharing the same ecological niche. Results emphasize the continuous evolution of V. vulnificus and support the emergence of new pathogenic groups within this species as a recurrent phenomenon. Our findings contribute to a broader understanding of the evolution of this human pathogen

Vibrio vulnificus Typing Based on Simple Sequence Repeats: Insights into the Biotype 3 Group▿ †

Vibrio vulnificus is an opportunistic, highly invasive human pathogen with worldwide distribution. V. vulnificus strains are commonly divided into three biochemical groups (biotypes), most members of which are pathogenic. Simple sequence repeats (SSR) provide a source of high-level genomic polymorphism used in bacterial typing. Here, we describe the use of variations in mutable SSR loci for accurate and rapid genotyping of V. vulnificus. An in silico screen of the genomes of two V. vulnificus strains revealed thousands of SSR tracts. Twelve SSR with core motifs longer than 5 bp in a panel of 32 characterized and 56 other V. vulnificus isolates, including both clinical and environmental isolates from all three biotypes, were tested for polymorphism. All tested SSR were polymorphic, and diversity indices ranged from 0.17 to 0.90, allowing a high degree of discrimination among isolates (27 of 32 characterized isolates). Genetic analysis of the SSR data resulted in the clear distinction of isolates that belong to the highly virulent biotype 3 group. Despite the clonal nature of this new group, SSR analysis demonstrated high-level discriminatory power within the biotype 3 group, as opposed to other molecular methods that failed to differentiate these isolates. Thus, SSR are suitable for rapid typing and classification of V. vulnificus strains by high-throughput capillary electrophoresis methods. SSR (≥5 bp) by their nature enable the identification of variations occurring on a small scale and, therefore, may provide new insights into the newly emerged biotype 3 group of V. vulnificus and may be used as an efficient tool in epidemiological studies

Amplified Intergenic Locus Polymorphism as a Basis for Bacterial Typing of Listeria spp. and Escherichia coli

DNA-based methods are increasingly important for bacterial typing. The high number of polymorphic sites present among closely related bacterial genomes is the basis for the presented method. The method identifies multilocus genomic polymorphisms in intergenic regions termed AILP (amplified intergenic locus polymorphism). For each locus, a pair of unique PCR primers was designed to amplify an intergenic sequence from one open reading frame (ORF) to the adjacent ORF. Presence, absence, and size variation of the amplification products were identified and used as genetic markers for rapidly differentiating among strains. Polymorphism was evaluated using 18 AILP sites among 28 strains of Listeria monocytogenes and 6 strains of Listeria spp. and 30 AILP markers among 27 strains of Escherichia coli. Up to four alleles per locus were identified among Listeria strains, and up to six were identified among E. coli strains. In both species, more than half of the AILP sites revealed intraspecies polymorphism. The AILP data were applied to phylogenetic analysis among Listeria and E. coli strains. A clear distinction between L. monocytogenes and Listeria spp. was demonstrated. In addition, the method separated L. monocytogenes into the three known lineages and discriminated the most common virulent serotypic group, 4b. In E. coli, AILP analysis separated the known groups as well as the virulent O157:H7 isolates. These findings for both Listeria and E. coli are in agreement with other phylogenetic studies using molecular markers. The AILP method was found to be rapid, simple, reproducible, and a low-cost method for initial bacterial typing that could serve as a basis for epidemiological investigation

<i>Vibrio cholerae</i> Autoinducer CAI-1 Interferes with <i>Pseudomonas aeruginosa</i> Quorum Sensing and Inhibits its Growth

The human pathogen <i>Vibrio cholerae</i> uses several small molecules to coordinate gene expression in a process termed quorum sensing (QS), and its main autoinducer is CAI-1. We have examined the activity of this signaling molecule in three other species of bacteria. Interestingly, while showing an inhibitory effect on QS in the opportunistic pathogen <i>P. aeruginosa</i> at low micromolar concentrations, it caused also growth inhibition at higher concentrations. In contrast, the two other bacteria were unaffected, and we suggest a possible mechanism for these effects, based on membrane perturbation studies

Environmental monitoring of Vibrio cholerae using chironomids in India

Environmental Vibrio cholerae strains belonging to the non-O1/non-O139 serogroups are natural inhabitants of freshwater including estuarine environments. Recent findings indicated that chironomids (Diptera: Chironomidae), the most widely distributed insects in freshwater, serve as a natural reservoir of these bacteria. Here we study the role of chironomids, particularly exuviae as carriers and as a monitoring tool for the distribution of V. cholerae in the environment. During a survey conducted in India (June 2006), 326 V. cholerae non-O1/non-O139 isolates were isolated from chironomid egg masses, larvae and exuviae. In addition, a heat-stable enterotoxin (nag-st) positive strain was isolated from exuviae during the local cholera outbreak. We identified 62 different strains in a subset of 102 isolates by analysis of variable number of tandem repeats (VNTR), demonstrating a high variation of V. cholerae on hosting chironomids. Our results show that chironomids can both maintain and distribute this overwhelming diversity of environmental V. cholerae strains, including toxigenic ones. Exuviae proved to be an efficient tool for the monitoring of environmental V. cholerae, offering simple, direct and practical access for on-shore collection. Finally, finding toxigenic V. cholerae on chironomids in endemic areas, together with molecular typing, may potentially improve monitoring of cholera in the future

ICEV<i>ch</i>Ind5 is prevalent in epidemic <i>Vibrio cholerae</i> O1 El Tor strains isolated in India

Integrative conjugative elements (ICEs) of the SXT/R391 family are self-transmissible mobile elements mainly involved in antibiotic resistance spread among &#x3b3;-Proteobacteria, including Vibrio cholerae. We demonstrated that the recently described ICEVchInd5 is prevailing in V. cholerae O1 clinical strains isolated in Wardha province (Maharashtra, India) from 1994 to 2005. Genetic characterization by ribotyping and multiple-locus SSR analysis proved the same clonal origin for V. cholerae O1 isolates in Wardha province over an 11-year period and was used to assess the correlation between strain and ICE content among ours and different Indian reference strains. In silico analysis showed the existence of at least 3 sibling ICEs of ICEVchInd5 in V. cholerae O1 El Tor reference strains, isolated in the Indian subcontinent after 1992