High quality reference genomes for toxigenic and non-toxigenic Vibrio cholerae serogroup O139.

Toxigenic Vibrio cholerae of the O139 serogroup have been responsible for several large cholera epidemics in South Asia, and continue to be of clinical and historical significance today. This serogroup was initially feared to represent a new, emerging V. cholerae clone that would lead to an eighth cholera pandemic. However, these concerns were ultimately unfounded. The majority of clinically relevant V. cholerae O139 isolates are closely related to serogroup O1, biotype El Tor V. cholerae, and comprise a single sublineage of the seventh pandemic El Tor lineage. Although related, these V. cholerae serogroups differ in several fundamental ways, in terms of their O-antigen, capsulation phenotype, and the genomic islands found on their chromosomes. Here, we present four complete, high-quality genomes for V. cholerae O139, obtained using long-read sequencing. Three of these sequences are from toxigenic V. cholerae, and one is from a bacterium which, although classified serologically as V. cholerae O139, lacks the CTXφ bacteriophage and the ability to produce cholera toxin. We highlight fundamental genomic differences between these isolates, the V. cholerae O1 reference strain N16961, and the prototypical O139 strain MO10. These sequences are an important resource for the scientific community, and will improve greatly our ability to perform genomic analyses of non-O1 V. cholerae in the future. These genomes also offer new insights into the biology of a V. cholerae serogroup that, from a genomic perspective, is poorly understood.

[TYPING OF VIBRIO CHOLERAE NON O1/NON O139 STRAINS, ISOLATED IN ROSTOV REGION IN 2014].

AIM: Comparative study of antibiotics resistance and VNTR-typing of Vibrio cholerae non O1/ non O139 strains, isolated on the territory of Rostov region in 2014. MATERIALS AND METHODS: Antibioticogramms of strains were determined by serial dilution method in dense nutrient medium according to MG 4.2.2495-09 (2009). Pheno-, sero- and VNTR-typing was carried out by conventional-methods. RESULTS: The studied strains belonged to V. cholerae species, did not agglutinate with O1 and O139 sera, were atoxigenic hemolysis-positive, did not contain genes of cholera toxin and toxin-coregulating pili of adhesion, contained genes of hemagglutinin/protease, protease PrtV, collagenase, cytotonic factor Cef, outer membrane protein-OmpW, tol- and -vps-clusters, regulatory genes toxR and hapR. Antibioticogramms of the strains have shown the presence of cultures, resistant to ampicillin, ceftazidime-furazolidone, trimethoprim/sulfamethoxazole with intermediate resistance to streptomycin, kanamycin, gentamycin, amikacin, netilmicin, Approximately 20% of isolates had multiple drug resistance. Data of VNTR- and genotyping confirmed a possibility of water transmission route of the infection. CONCLUSION: Execution of monitoring of cultures from environmental samples is necessary for timely detection of genetic characteristics, antibiotics resistance.

Characterization of environmental Vibrio cholerae serogroups O1 and O139 in the Pearl River Estuary, China.

Toxigenic isolates of Vibrio cholerae serogroups O1 and O139 from aquatic reservoirs are a key source for recurrent epidemics of cholera in human populations. However, we do not have an optimal understanding of the microbiology of the strains within these reservoirs, particularly outside of the time periods when there are active cholera cases in the surrounding community. The main objective of the present study was to identify and characterize V. cholerae O1 and O139 in the Pearl River Estuary at a time when active disease was not being identified, despite prior occurrence of epidemic cholera in the region. Water samples were collected at 24 sites in the research area at monthly intervals between 2007 and 2010, and screened for the presence of V. cholerae O1 and O139. All isolates were screened for the presence of ctxAB, ompW, toxR, and tcpA genes. Multilocus variable number tandem repeat analysis (MLVA) was used to assess possible relationships among strains. The results show that Vibrio cholerae O1 or O139 was isolated, on average, from 6.7% of the sites screened at each time point. All V. cholerae O1 and O139 isolates were ctxAB negative, and 37% were positive for tcpA. Isolation was most common in the oldest, most urbanized district compared with other districts, and was associated with lower pH. Despite year-to-year variability in isolation rates, there was no evidence of seasonality. MLVA of 27 selected isolates showed evidence of high genetic diversity, with no evidence of clustering by year or geographic location. In this region where cholera has been epidemic in the past, there is evidence of environmental persistence of V. cholerae O1 and O139 strains. However, environmental strains were consistently nontoxigenic, with a high level of genetic diversity; their role as current or future agents of human disease remains uncertain.

Phylodynamic analysis of clinical and environmental Vibrio cholerae isolates from Haiti reveals diversification driven by positive selection.

UNLABELLED: Phylodynamic analysis of genome-wide single-nucleotide polymorphism (SNP) data is a powerful tool to investigate underlying evolutionary processes of bacterial epidemics. The method was applied to investigate a collection of 65 clinical and environmental isolates of Vibrio cholerae from Haiti collected between 2010 and 2012. Characterization of isolates recovered from environmental samples identified a total of four toxigenic V. cholerae O1 isolates, four non-O1/O139 isolates, and a novel nontoxigenic V. cholerae O1 isolate with the classical tcpA gene. Phylogenies of strains were inferred from genome-wide SNPs using coalescent-based demographic models within a Bayesian framework. A close phylogenetic relationship between clinical and environmental toxigenic V. cholerae O1 strains was observed. As cholera spread throughout Haiti between October 2010 and August 2012, the population size initially increased and then fluctuated over time. Selection analysis along internal branches of the phylogeny showed a steady accumulation of synonymous substitutions and a progressive increase of nonsynonymous substitutions over time, suggesting diversification likely was driven by positive selection. Short-term accumulation of nonsynonymous substitutions driven by selection may have significant implications for virulence, transmission dynamics, and even vaccine efficacy. IMPORTANCE: Cholera, a dehydrating diarrheal disease caused by toxigenic strains of the bacterium Vibrio cholerae, emerged in 2010 in Haiti, a country where there were no available records on cholera over the past 100 years. While devastating in terms of morbidity and mortality, the outbreak provided a unique opportunity to study the evolutionary dynamics of V. cholerae and its environmental presence. The present study expands on previous work and provides an in-depth phylodynamic analysis inferred from genome-wide single nucleotide polymorphisms of clinical and environmental strains from dispersed geographic settings in Haiti over a 2-year period. Our results indicate that even during such a short time scale, V. cholerae in Haiti has undergone evolution and diversification driven by positive selection, which may have implications for understanding the global clinical and epidemiological patterns of the disease. Furthermore, the continued presence of the epidemic strain in Haitian aquatic environments has implications for transmission.

High prevalence and diversity of pre-CTXΦ alleles in the environmental Vibrio cholerae†O1 and O139 strains in the Zhujiang River estuary.

Toxigenic conversion of environmental Vibrio cholerae strains through lysogenic infection by the phage CTXΦ is an important step in the emergence of new pathogenic clones. The precursor form of the CTXΦ phage, pre-CTXΦ, does not carry the cholera toxin gene. During our investigation, we frequently found pre-CTXΦ prophages in non-toxigenic isolates in the serogroups of O1 and O139 strains in the Zhujiang estuary. We observed high amounts of sequence variation of rstR and gIII(CTX) in the pre-CTXΦ alleles as well as in the tcpA sequences within the strains. In addition, a new pre-CTXΦ allele, with a novel rstR sequence type and hybrid RS2, was identified. Our findings show that active, complicated gene recombination and horizontal transfer of pre-CTXΦs occurs within V. cholerae environmental strains, which creates a complex intermediate pool for the generation of toxigenic clones in the estuarine environment.

Distribution of virulence-associated genes and genetic relationships in non-O1/O139 Vibrio cholerae aquatic isolates from China.

Non-O1/O139 Vibrio cholerae is naturally present in aquatic ecosystems and has been linked with cholera-like diarrhea and local outbreaks. The distribution of virulence-associated genes and genetic relationships among aquatic isolates from China are largely unknown. In this study, 295 aquatic isolates of V. cholerae non-O1/O139 serogroups from different regions in China were investigated. Only one isolate was positive for ctxB and harbored a rare genotype; 10 (3.4%) isolates carried several types of rstR sequences, eight of which carried rare types of toxin-coregulated pili (tcpA). Furthermore, 16 (5.4%) isolates carried incomplete (with partial open reading frames [ORFs]) vibrio seventh pandemic island I (VSP-I) or VSP-II clusters, which were further classified as 11 novel types. PCR-based analyses revealed remarkable variations in the distribution of putative virulence genes, including mshA (95.6%), hlyA (95.3%), rtxC (89.8%), rtxA (82.7%), IS1004 (52.9%), chxA (30.2%), SXT (15.3%), type III secretion system (18.0%), and NAG-ST (3.7%) genes. There was no correlation between the prevalence of putative virulence genes and that of CTX prophage or TCP genes, whereas there were correlations among the putative virulence genes. Further multilocus sequence typing (MLST) placed selected isolates (n = 70) into 69 unique sequence types (STs), which were different from those of the toxigenic O1 and O139 counterparts, and each isolate occupied a different position in the MLST tree. The V. cholerae non-O1/O139 aquatic isolates predominant in China have high genotypic diversity; these strains constitute a reservoir of potential virulence genes, which may contribute to evolution of pathogenic isolates.

A molecular surveillance reveals the prevalence of Vibrio cholerae O139 isolates in China from 1993 to 2012.

Vibrio cholerae serogroup O139 was first identified in 1992 in India and Bangladesh, in association with major epidemics of cholera in both countries; cases were noted shortly thereafter in China. We characterized 211 V. cholerae O139 isolates that were isolated at multiple sites in China between 1993 and 2012 from patients (n = 92) and the environment (n = 119). Among clinical isolates, 88 (95.7%) of 92 were toxigenic, compared with 47 (39.5%) of 119 environmental isolates. Toxigenic isolates carried the El Tor CTX prophage and toxin-coregulated pilus A gene (tcpA), as well as the Vibrio seventh pandemic island I (VSP-I) and VSP-II. Among a subset of 42 toxigenic isolates screened by multilocus sequence typing (MLST), all were in the same sequence type as a clinical isolate (MO45) from the original Indian outbreak. Nontoxigenic isolates, in contrast, generally lacked VSP-I and -II, and fell within 13 additional sequence types in two clonal complexes distinct from the toxigenic isolates. In further pulsed-field gel electrophoresis (PFGE) (with NotI digestion) studies, toxigenic isolates formed 60 pulsotypes clustered in one group, while the nontoxigenic isolates formed 43 pulsotypes which clustered into 3 different groups. Our data suggest that toxigenic O139 isolates from widely divergent geographic locations, while showing some diversity, have maintained a relatively tight clonal structure across a 20-year time span. Nontoxigenic isolates, in contrast, exhibited greater diversity, with multiple clonal lineages, than did their toxigenic counterparts.

A three-loci variable number of tandem repeats analysis for molecular subtyping of Vibrio cholerae O1 and O139.

Rapid and easy-to-use molecular subtyping methods are being explored and used for the surveillance of bacterial diseases, including multiple-loci variable number of tandem repeats (VNTR) analysis (MLVA). In this study, we assessed different VNTR combinations for the subtyping of Vibrio cholerae serogroups O1 and O139 with strain panels selected from a long-term nationwide cholera survey. By only using three highly variable loci (VC0147, VCA0171, and VCA0283), we acquired a high discriminatory power, which equals that found after using a combination of all nine loci and that of a pulsed-field gel electrophoresis analysis. Evaluation using the outbreak strains showed a good clustering of the three-loci MLVA (VC0147, VCA0171, and VCA0283). In addition, a six-loci MLVA (VC0147, VC0437, VC1457, VC1650, VCA0171, and VCA0283) protocol allowed for the clustering of O1/O139 V. cholerae strains, which have different serogroups/biotypes and toxigenic/nontoxigenic characteristics. Here, we propose that the three-loci MLVA can be utilized as a molecular subtyping protocol in cholera epidemiological investigations, and the six-loci MLVA can be used in phylogenetic and population structure analyses of V. cholerae O1/O139.

Prevalence and molecular characterization of Vibrio cholerae O1, non-O1 and non-O139 in tropical seafood in Cochin, India.

The objective of this study was to determine the prevalence of O1, O139, and non-O1 and non-O139 Vibrio cholerae, which were associated with fresh and raw seafood samples harvested from Cochin, India waters during 2009-2011. Results from V. cholerae-specific biochemical, molecular, and serological assays identified five El Tor V. cholerae O1 Ogawa strains and 377 non-O1, non-O139 V. cholerae strains from 265 seafood samples. V. cholerae O139 strains were not isolated. Polymerase chain reaction assays confirmed the presence of V. cholerae O1 El Tor biotype in seafood. Antibiotic susceptibility analysis revealed that the V. cholerae O1 strains were pansusceptible to 20 test antibiotics, whereas 26%, 40%, 62%, and 84% of the non-O1, non-O139 V. cholerae strains were resistant to cefpodoxime, ticarcillin, augmentin, and colistin, respectively. Detection of virulence and regulatory genes in V. cholerae associated with seafood revealed the presence of virulence and regulatory genes (i.e., ctx, zot, ace, toxR genes) in V. cholerae O1 strains, nevertheless, presence of ace and toxR genes were detected in non-O1, non-O139 in 9.8 and 91% strains, respectively. In conclusion, the presence of pathogenic V. cholerae in seafood harvested from local Cochin waters warrants the introduction of a postharvest seafood monitoring program, which will lead to a greater understanding of the distribution, abundance, and virulence of diverse pathogenic Vibrio populations that inhabit these different coastal regions so that a risk management program can be established.

[Characteristics of Vibrio cholerae nonO1/nonO139 serogroup strains that caused diseases in population of Rostov region].

AIM: Genotype characteristic and determination of serological properties of Vibrio cholerae nonO1/nonO139 strains that caused diseases in population of Rostov region from 2000 to 2009. MATERIALS AND METHODS: 15 clinical strains of V. cholerae nonO1/nonO139 were studied. Serotyping was performed by using a kit of monospecific typing sera against serogroup 02-084 cholera vibrios obtained from Rostov Research Institute for Plague Control, PCR and VNTR-genotyping--by using specific primers described in scientific publications and constructed by us. RESULTS: Serologic features of strains are very diverse and strains contain various combination of pathogenicity factor genes that seem to be interchangeable. Similar pattern was observed for VNTR-genotyping. Distribution of the examined strains by VNTR-genotyping did not correlate with either PCR-genotyping data or serotyping, or place and time of isolation. CONCLUSION: The data obtained indicates a lack of general source of human infection even in the same location and time period. On the other hand, serological and genotypic features of V. cholerae nonO1/nonO139 may undergo changes in the process of staying in the macro organism or environment due to high plasticity of their genome.

Phage types of Vibrio cholerae O1 and O139 in the past decade in India.

Cholera has been a prevalent disease worldwide since the early 19th century. Vibrio cholerae O1 and O139 are the two serogroups that have been mainly implicated in causing cholera. This study reports the results of biotyping, serotyping and phage typing of V. cholerae O1 and O139 (1998-2007) strains received from different parts of India for the identification of the trends in the occurrence and spread of cholera in the country. However, there has been a notable steep decline in the occurrence of V. cholerae O139 strains over the past few years resulting in no strain of V. cholerae O139 being received from any part of India in 2007 and 2008. Of the total strains received, 79.1% were serotyped as Ogawa and the remaining 20.9% were found to be Inaba, which indicates that Ogawa was the predominant serotype. Almost 100% typeability was observed with the new scheme of V. cholerae O1, with type 27 being the dominant phage type and V. cholerae O139 strains were clustered into the predominant phage type T-1. From the phage typing and serotyping results, it can be concluded that V. cholerae O1 (T-27) and O139 (T-1) strains circulate throughout the country at any given time.

Characterization of Vibrio cholerae O139 belonging to multiple ribotypes and isolated from diarrhoeal patients in Kerala, southern India.

Twenty-four Vibrio cholerae O139 strains isolated from Kerala, southern India were characterized by PCR, CTX typing and ribotyping; all of which, except three strains, carried the core of the CTX genetic element, colonization-toxin co-regulated pilus, the adherence outer membrane protein, haemolysin, central regulatory protein encoded toxR, SXT genetic element, and produced cholera toxin and biofilm. Results of RFLP analysis revealed twenty-one of the O139 strains possess two copies of CTXΦ and pre-CTXФ always preceded by tandemly arranged RS1 element; one had two copies of pre-CTXΦ and two a single copy of pre-CTXΦ. Nucleotide sequencing detected classical ctxB in CTX(ET)Φ and CTX(Calc)Ф with additional change at 28th amino acid position of CTX(Calc)Ф. Ribotype analysis revealed the presence of multiple ribotypes, including B-I and B-II, and new ribotypes designated B-VIIIa, B-VIIIb and B-IX, not reported earlier among V. cholerae O139 strains. These observations thus indicate that genetic recombination or mutations had occurred in conserved rrn operon and variations in CTXΦ may have implications on the evolution of the organism.

[In vitro induction of transmissive resistance to tetracycline, chloramphenicol and ampicillin chloramphenicol in Vibrio cholera non-O1/non-O139 serogroups isolated within 1990-2005].

Inducible character of resistance to tetracycline, chloramphenicol and ampicillin was investigated in 20 strains of Vibrio cholera non-O1/non-O139 serogroups isolated from inhabitants of Uzbekistan in 1990 (10 strains, ctx+) and in 2001 (5 strains, ctx-) and from inhabitants of Kalmykiya within 2003-2005 (5 strains, ctx-). Eight of the 20 isolates showed not only capacity for induction of the antibiotic resistance, but also its possible self transfer to Escherichia coli and reverse crosses in El Tor V. cholerae P-5879. It was shown that the effect of the antibacterial on the isolates phenotypic susceptibility could increase the resistance markers expression, when the genomes contained sites responsible for their expression, that required constant bacteriological control of the treatment efficacy and the use of the isolates antibioticograms for early replace of the inefficient drug by the efficient one. The prevalence of V. cholerae O1 and non-O1/non-O13 serogroups with multiple resistance to the antibacterial and the genetic potency for the antibiotic resistance development in the pathogen made difficult the choice of efficient drugs for prophylaxis and treatment of diseases caused by V. cholerae.

Phenotypic and genotypic characterization Vibrio cholerae O139 of clinical and aquatic isolates in China.

To enhance the understanding of epidemiological impact of environmental Vibrio cholerae O139 strains, we characterized 10 clinical and 20 environmental isolates collected from human clinical samples and Pear River estuary during 2006 to 2008. Isolates were tested by PCR for eight virulence genes: cholera toxin (ctxA), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), hemolysin (hlyA), NAG-specific heat-stable toxin (st), toxin-coregulated pilus (tcpA), outer membrane protein (ompU), and regulatory protein genes (tcpI). Genetic relatedness was assessed by pulsed-field gel electrophoresis (PFGE), and antibiotic susceptibility was determined using disk diffusion. Seven of eight virulence markers were detected in six clinical isolates and one environmental isolate. One clinical and one environmental isolate were positive for six virulence markers. 60% clinical isolates showed multi-drug resistance to tetracycline (TET), Nalidixic acid (NAL), chloramphenicol (CHL), and ampicillin (AMP), 70% were resistant to Trimethoprim + Sulfamethoxazole (SXT), while only 35% environmental strains were resistant to SXT. PFGE analysis revealed that the isolates in this study were formed three clusters. Cluster III was more related to strains from diarrheal patients than the strains in other clusters. Different from the clinical strains, most environmental strains lacked CTX and TCP gene clusters. Most environmental strains possess a single resistance profile, while most clinical isolates show multidrug resistant. PFGE analysis indicated the cluster III has more possibility to become a potential pathogenic clonal cluster.

Comparison of amplified fragment length polymorphism and pulsed-field gel electrophoresis for subtyping of Vibrio cholerae serogroups O1 and O139.

Molecular typing of Vibrio cholerae strains is a powerful tool for the surveillance of cholera. Amplified fragment length polymorphism (AFLP) is considered to be a powerful subtyping technique to distinguish bacterial strains at the genetic level. Optimization and standardization of AFLP protocol is required to allow data comparisons across different laboratories in a surveillance network. Here, we performed AFLP using different restriction enzymes and primer pairs for subtyping of V. cholerae serogroups O1 and O139 and compared the optimized AFLP protocol with pulsed-field gel electrophoresis (PFGE) to evaluate the applicability of AFLP for conducting epidemiological surveillance of cholera. The discriminatory index (D-value) of PFGE for serogroup O1 strains was similar when digested with NotI and SfiI, whereas that for O139 strains was higher for NotI digestion than for SfiI. EcoRI-G/MseI-T was the restriction enzyme and primer combination with highest discriminatory index used in the AFLP analysis. Capillary electrophoresis-based AFLP showed higher discriminatory power than that of polyacrylamide gel electrophoresis-based AFLP. When the two methods were compared using 72 epidemiologically unrelated serogroup O1 El Tor isolates, AFLP had a lower D-value than PFGE with NotI and SfiI digestions, respectively. For 54 epidemiologically unrelated serogroup O139 isolates, NotI PFGE had the highest discriminatory power, and SfiI PFGE and AFLP yielded almost the same but lower discriminatory power. We conclude that NotI and SfiI are both suitable for the PFGE of V. cholerae serogroup O1, whereas NotI should be defined as the primary enzyme for serogroup O139. The applicability of AFLP in V. cholerae subtyping and outbreak investigations is limited.

Effect of storage and sodium chloride on excision of CTXPhi or pre-CTXPhi and CTXPhi from Vibrio cholerae O139 strains.

We examined the effect of storage and sodium chloride on excision of CTXPhi or pre-CTXPhi and CTXPhi from Vibrio cholerae O139 strains. We found that one strain of V. cholerae O139 VO146P showed loss of the complete phage array, and other strain VO170P showed partial loss of the phage array giving rise to altered strains designated as VO146N and VO170N. Results of PCR and RFLP analysis revealed that both strains (VO146P and VO170P) possessed a single copy of pre-CTX(ET)Phi and two copies of CTXPhi comprising CTX(Class)Phi and CTX(Calc)Phi arranged in tandem, and integrated in the large chromosome. The presence of classical ctxB was detected in CTX(Calc)Phi of both V. cholerae O139 strains. Nucleotide sequencing of three housekeeping genes showed no difference between parent and altered strains of V. cholerae O139.

Relatedness of Vibrio cholerae O1/O139 isolates from patients and their household contacts, determined by multilocus variable-number tandem-repeat analysis.

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.

[Serotyping and genotypic characteristic of Vibrio cholerae non-O1/non-O139 serogroups isolated from water of surface basins and sewages of Rostov-on-Don city in 2003 - 2008].

AIM: Determination of serogroup and PCR-genotyping of Vibrio cholerae non-O1/non-O139 strains isolated from surface basins and sewages of Rostov-on-Don city in 2003 - 2008. MATERIALS AND METHODS: Seven hundred strains of V. cholerae non-O1/non-O139 serogroups were studied in reaction of slide-agglutination with array of 80 diagnostic sera for non-O1/non-O139 serogroups. Selective screening of strains representing dominating serogroups was performed for extended number of genetic determinants of pathogenicity factors. RESULTS: It was established that V. cholerae belonging to serogroups O53, O67, O75, and O76 are dominating in water ecosystems of Rostov-on-Don city at this time. All studied strains were characterized by lack of cholera toxin genes and toxin-coregulated pili but had different combinations of genes of additional virulence factors. There was no correlation between genotypic characteristics and serogroup. CONCLUSION: The study showed that change of serologic landscape of V. cholerae non-O1/non-O139 occurred in water objects in studied area during last decades. Necessity of dynamic surveillance for circulation of V. cholerae non-O1/non-O139 in aquatic environment with widening of studied spectrum of their biological features was demonstrated.

Epidemiological study of Vibrio cholerae using variable number of tandem repeats.

By conventional genetic methods, including pulse-field gel electrophoresis and multilocus sequence typing, most pathogenic, cholera toxin-positive O1 and O139 isolates of Vibrio cholerae cannot be distinguished. We evaluated relationships among 173 V. cholerae isolates collected between 1992 and 2007 from different geographic areas in India by analyzing five variable number of tandem repeat (VNTR) loci. Each VNTR locus was highly variable, with between 5 and 19 alleles. eburst analysis revealed four large groups of genetically related isolates. Two groups contained genotypes of isolates with the O139 serogroup (which emerged for the first time in epidemic form in 1992), with the other two groups containing O1 strains. In subsequent analysis, it was possible to track the spread of specific genotypes across time and space. Our data highlight the utility of the methodology as an epidemiologic tool for assessing spread of isolates in both epidemic and endemic settings.