Last data update: Nov 11, 2024. (Total: 48109 publications since 2009)
Records 1-30 (of 30 Records) |
Query Trace: Tarr CL[original query] |
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Emergence and global spread of Listeria monocytogenes main clinical clonal complex (preprint)
Moura A , Lefrancq N , Leclercq A , Wirth T , Borges V , Gilpin B , Dallman TJ , Frey J , Franz E , Nielsen EM , Thomas J , Pightling A , Howden BP , Tarr CL , Gerner-Smidt P , Cauchemez S , Salje H , Brisse S , Lecuit M . bioRxiv 2020 2020.12.18.423387 Retracing microbial emergence and spread is essential to understanding the evolution and dynamics of pathogens. The bacterial foodborne pathogen Listeria monocytogenes clonal complex 1 (Lm-CC1) is the most prevalent clonal group associated with listeriosis, and is strongly associated with cattle and dairy products. Here we analysed 2,021 Lm-CC1 isolates collected from 40 countries, since the first Lm isolation to the present day, to define its evolutionary history and population dynamics. Our results suggest that Lm-CC1 spread worldwide from North America following the Industrial Revolution through two waves of expansion, coinciding with the transatlantic livestock trade in the second half of the 19th century and the rapid growth of cattle farming in the 20th century. Lm-CC1 then firmly established at a local level, with limited inter-country spread. This study provides an unprecedented insight into Lm-CC1 phylogeography and dynamics and can contribute to effective disease surveillance to reduce the burden of listeriosis.Competing Interest StatementThe authors have declared no competing interest. |
Population analysis of Vibrio cholerae in aquatic reservoirs reveals a novel sister species (Vibrio paracholerae sp. nov.) with a history of association with human infections (preprint)
Islam MT , Nasreen T , Kirchberger P , Liang KYH , Orata FD , Johura FT , Im MS , Tarr CL , Alam M , Boucher YF . bioRxiv 2021 2021.05.05.442690 Most efforts to understand the biology of Vibrio cholerae have focused on a single group, the pandemic-generating lineage harbouring the strains responsible for all known cholera pandemics. Consequently, little is known about the diversity of this species in its native aquatic environment. To understand the differences in the V. cholerae populations inhabiting in regions with varying history of cholera cases and how that might influence the abundance of pandemic strains, a comparative analysis of population composition was performed. Little overlap was found in lineage compositions between those in Dhaka (cholera endemic) located in the Ganges delta, and of Falmouth (no known history of cholera), a small coastal town on the US East Coast. The most striking difference was the presence of a group of related lineages at high abundance in Dhaka which was completely absent from Falmouth. Phylogenomic analysis revealed that these lineages form a cluster at the base of the phylogeny of V. cholerae species, sufficiently differentiated genetically and phenotypically to form a novel species. Strains from this species have been anecdotally isolated from around the world and were isolated as early as 1916 from a British soldier in Egypt suffering from choleraic diarrhoea. In 1935 Gardner and Venkatraman unofficially referred to a member of this group as Vibrio paracholerae. In recognition of this earlier designation, we propose the name Vibrio paracholerae, sp. nov. for this bacterium. Genomic analysis suggests a link with human populations for this novel species and substantial interaction with its better-known sister species.Importance Cholera continues to remain a major public health threat around the globe. Understanding the ecology, evolution and environmental adaptation of the causative agent Vibrio cholerae and tracking the emergence of novel lineages with pathogenic potential are essential to combat the problem. In this study, we investigated the population dynamics of Vibrio cholerae in an inland locality which is known as endemic for cholera and compared with that of a cholera free coastal location. We found the consistent presence of the pandemic generating V. cholerae in cholera-endemic Dhaka and an exclusive presence of a lineage phylogenetically distinct from other V. cholerae. Our study suggests that this lineage represents a novel species having pathogenic potential and a human link to its environmental abundance. The possible association with human population, co-existence and interaction with toxigenic V. cholerae in the natural environment make this potential human pathogen an important subject for future studies.Competing Interest StatementThe authors have declared no competing interest. |
A Vibrio cholerae Core Genome Multilocus Sequence Typing Scheme to Facilitate the Epidemiological Study of Cholera (preprint)
Liang KYH , Orata FD , Islam MT , Nasreen T , Alam M , Tarr CL , Boucher YF . bioRxiv 2020 2020.01.27.919118 Core genome multilocus sequence typing (cgMLST) has gained popularity in recent years in epidemiological research and subspecies level classification. cgMLST retains the intuitive nature of traditional MLST but offers much greater resolution by utilizing significantly larger portions of the genome. Here, we introduce a cgMLST scheme for Vibrio cholerae, a bacterium abundant in marine and freshwater environments and the etiologic agent of cholera. A set of 2,443 core genes ubiquitous in V. cholerae were used to analyze a comprehensive dataset of 1,262 clinical and environmental strains collected from 52 countries, including 65 newly sequenced genomes in this study. We established a sublineage threshold based on 133 allelic differences that creates clusters nearly identical to traditional MLST types, providing backwards compatibility to new cgMLST classifications. We also defined an outbreak threshold based on seven allelic differences that is capable of identifying strains from the same outbreak and closely related isolates which could give clues on outbreak origin. Using cgMLST, we confirmed the South Asian origin of modern epidemics and identified clustering affinity among sublineages of environmental isolates from the same geographic origin. Advantages of this method are highlighted by direct comparison with existing classification methods, such as MLST and single nucleotide polymorphism-based methods. cgMLST outperforms all existing methods in terms of resolution, standardization, and ease-of-use. We anticipate this scheme will serve as a basis for a universally applicable and standardized classification system for V. cholerae research and epidemiological surveillance in the future. This cgMLST scheme is publicly available on PubMLST (https://pubmlst.org/vcholerae/).IMPORTANCE Toxigenic Vibrio cholerae of the O1 and O139 serogroups are the causative agent of cholera, an acute diarrheal disease that plagued the world for centuries, if not millennia. Here, we introduce a core genome multilocus sequence typing (cgMLST) scheme for V. cholerae. Using cgMLST, we established an outbreak threshold that can efficiently identify outbreak related strains and potential sources of introduction. We also defined a sublineage threshold that is similar to traditional MLST sequence type which will provide context to this new typing method by relating it to previous MLST results. cgMLST outperforms all existing methods in terms of resolution, standardization, and ease-of-use, making this scheme the most suitable method for V. cholerae typing and surveillance worldwide. |
Characterization of a nonagglutinating toxigenic vibrio cholerae isolate
Gladney LM , Griswold T , Turnsek M , Im MS , Parsons MMB , Katz LS , Tarr CL , Lee CC . Microbiol Spectr 2023 11 (3) e0018223 Toxigenic Vibrio cholerae serogroup O1 is the etiologic agent of the disease cholera, and strains of this serogroup are responsible for pandemics. A few other serogroups have been found to carry cholera toxin genes-most notably, O139, O75, and O141-and public health surveillance in the United States is focused on these four serogroups. A toxigenic isolate was recovered from a case of vibriosis from Texas in 2008. This isolate did not agglutinate with any of the four different serogroups' antisera (O1, O139, O75, or O141) routinely used in phenotypic testing and did not display a rough phenotype. We investigated several hypotheses that might explain the recovery of this potential nonagglutinating (NAG) strain using whole-genome sequencing analysis and phylogenetic methods. The NAG strain formed a monophyletic cluster with O141 strains in a whole-genome phylogeny. Furthermore, a phylogeny of ctxAB and tcpA sequences revealed that the sequences from the NAG strain also formed a monophyletic cluster with toxigenic U.S. Gulf Coast (USGC) strains (O1, O75, and O141) that were recovered from vibriosis cases associated with exposures to Gulf Coast waters. A comparison of the NAG whole-genome sequence showed that the O-antigen-determining region of the NAG strain was closely related to those of O141 strains, and specific mutations were likely responsible for the inability to agglutinate. This work shows the utility of whole-genome sequence analysis tools for characterization of an atypical clinical isolate of V. cholerae originating from a USGC state. IMPORTANCE Clinical cases of vibriosis are on the rise due to climate events and ocean warming (1, 2), and increased surveillance of toxigenic Vibrio cholerae strains is now more crucial than ever. While traditional phenotyping using antisera against O1 and O139 is useful for monitoring currently circulating strains with pandemic or epidemic potential, reagents are limited for non-O1/non-O139 strains. With the increased use of next-generation sequencing technologies, analysis of less well-characterized strains and O-antigen regions is possible. The framework for advanced molecular analysis of O-antigen-determining regions presented herein will be useful in the absence of reagents for serotyping. Furthermore, molecular analyses based on whole-genome sequence data and using phylogenetic methods will help characterize both historical and novel strains of clinical importance. Closely monitoring emerging mutations and trends will improve our understanding of the epidemic potential of Vibrio cholerae to anticipate and rapidly respond to future public health emergencies. |
Emergence and global spread of Listeria monocytogenes main clinical clonal complex.
Moura A , Lefrancq N , Wirth T , Leclercq A , Borges V , Gilpin B , Dallman TJ , Frey J , Franz E , Nielsen EM , Thomas J , Pightling A , Howden BP , Tarr CL , Gerner-Smidt P , Cauchemez S , Salje H , Brisse S , Lecuit M . Sci Adv 2021 7 (49) eabj9805 Retracing microbial emergence and spread is essential to understanding the evolution and 40 dynamics of pathogens. The bacterial foodborne pathogen Listeria monocytogenes clonal 41 complex 1 (Lm-CC1) is the most prevalent clonal group associated with listeriosis, and is 42 strongly associated with cattle and dairy products. Here we analysed 2,021 Lm-CC1 43 isolates collected from 40 countries, since the first Lm isolation to the present day, to 44 define its evolutionary history and population dynamics. Our results suggest that Lm-CC1 45 spread worldwide from North America following the Industrial Revolution through two 46 waves of expansion, coinciding with the transatlantic livestock trade in the second half of 47 the 19th century and the rapid growth of cattle farming in the 20th century. Lm-CC1 then 48 firmly established at a local level, with limited inter-country spread. This study provides 49 an unprecedented insight into Lm-CC1 phylogeography and dynamics and can contribute 50 to effective disease surveillance to reduce the burden of listeriosis. |
Population analysis of Vibrio cholerae in aquatic reservoirs reveals a novel sister species (Vibrio paracholerae sp. nov.) with a history of association with humans.
Islam MT , Nasreen T , Kirchberger P , Liang KYH , Orata FD , Johura FT , Hussain NAS , Im MS , Tarr CL , Alam M , Boucher YF . Appl Environ Microbiol 2021 87 (17) Aem0042221 Most efforts to understand the biology of Vibrio cholerae have focused on a single group, the pandemic-generating lineage harbouring the strains responsible for all known cholera pandemics. Consequently, little is known about the diversity of this species in its native aquatic environment. To understand the differences in the V. cholerae populations inhabiting regions with a history of cholera cases and those lacking such a history, a comparative analysis of population composition was performed. Little overlap was found in lineage compositions between those in Dhaka (cholera endemic) located in the Ganges delta, and of Falmouth (no known history of cholera), a small coastal town on the United States east coast. The most striking difference was the presence of a group of related lineages at high abundance in Dhaka which was completely absent from Falmouth. Phylogenomic analysis revealed that these lineages form a cluster at the base of the phylogeny for the V. cholerae species, sufficiently differentiated genetically and phenotypically to form a novel species. A retrospective search revealed that strains from this species have been anecdotally found from around the world and were isolated as early as 1916 from a British soldier in Egypt suffering from choleraic diarrhoea. In 1935 Gardner and Venkatraman unofficially referred to a member of this group as Vibrio paracholerae. In recognition of this earlier designation, we propose the name Vibrio paracholerae sp. nov. for this bacterium. Genomic analysis suggests a link with human populations for this novel species and substantial interaction with its better-known sister species. Importance Cholera continues to remain a major public health threat around the globe. Understanding the ecology, evolution, and environmental adaptation of the causative agent Vibrio cholerae and tracking the emergence of novel lineages with pathogenic potential are essential to combat the problem. In this study, we investigated the population dynamics of Vibrio cholerae in an inland locality which is known as endemic for cholera and compared with that of a cholera free coastal location. We found the consistent presence of the pandemic generating V. cholerae in cholera-endemic Dhaka and an exclusive presence of a lineage phylogenetically distinct from other V. cholerae. Our study suggests that this lineage represents a novel species having pathogenic potential and a human link to its environmental abundance. The possible association with human population, co-existence and interaction with toxigenic V. cholerae in the natural environment make this potential human pathogen an important subject for future studies. |
A Vibrio cholerae Core Genome Multilocus Sequence Typing Scheme to Facilitate the Epidemiological Study of Cholera.
Liang KYH , Orata FD , Islam MT , Nasreen T , Alam M , Tarr CL , Boucher YF . J Bacteriol 2020 202 (24) Core genome multilocus sequence typing (cgMLST) has gained popularity in recent years in epidemiological research and subspecies level classification. cgMLST retains the intuitive nature of traditional MLST but offers much greater resolution by utilizing significantly larger portions of the genome. Here, we introduce a cgMLST scheme for Vibrio cholerae, a bacterium abundant in marine and freshwater environments and the etiologic agent of cholera. A set of 2,443 core genes ubiquitous in V. cholerae were used to analyze a comprehensive dataset of 1,262 clinical and environmental strains collected from 52 countries, including 65 newly sequenced genomes in this study. We established a sublineage threshold based on 133 allelic differences that creates clusters nearly identical to traditional MLST types, providing backwards compatibility to new cgMLST classifications. We also defined an outbreak threshold based on seven allelic differences that is capable of identifying strains from the same outbreak and closely related isolates which could give clues on outbreak origin. Using cgMLST, we confirmed the South Asian origin of modern epidemics and identified clustering affinity among sublineages of environmental isolates from the same geographic origin. Advantages of this method are highlighted by direct comparison with existing classification methods, such as MLST and single nucleotide polymorphism-based methods. cgMLST outperforms all existing methods in terms of resolution, standardization, and ease-of-use. We anticipate this scheme will serve as a basis for a universally applicable and standardized classification system for V. cholerae research and epidemiological surveillance in the future. This cgMLST scheme is publicly available on PubMLST (https://pubmlst.org/vcholerae/).IMPORTANCEToxigenic Vibrio cholerae of the O1 and O139 serogroups are the causative agents of cholera, an acute diarrheal disease that plagued the world for centuries, if not millennia. Here, we introduce a core genome multilocus sequence typing scheme for V. cholerae Using this scheme, we have standardized the definition for subspecies-level classification, facilitating global collaboration in the surveillance of V. cholerae In addition, this typing scheme allows for quick identification of outbreak-related isolates that can guide subsequent analyses, serving as an important first step in epidemiological research. This scheme is also easily scalable to analyze thousands of isolates at various levels of resolution making it an invaluable tool for large-scale ecological and evolutionary analyses. |
Clonal spread of Yersinia enterocolitica 1B/O:8 in multiple zoo species
Hicks CL , Napier JE , Armstrong DL , Gladney LM , Tarr CL , Freeman MM , Iwen PC . J Zoo Wildl Med 2020 51 (1) 170-176 Yersinia enterocolitica (YE) bioserotype 1B/O:8 (YE 1B/O:8) was identified in routine culture of a variety of zoo species housed at Omaha's Henry Doorly Zoo and Aquarium (OHDZA) from April to July 2011. Animal cases representing 12 species had YE detected from 34 cases during routine fecal monitoring and/or during postmortem examination: Coquerel's sifakas (Propithecus coquereli, two cases), black & white (BW) ruffed lemurs (Varecia variegata variegata, six cases), red ruffed lemurs (Varecia rubra, seven cases), white handed gibbon (Hylobates lar albimana, one case), black lemurs (Eulemur macaco, three cases), mongoose lemurs (Eulemur mongoz, two cases), African hunting dogs (Lycaon pictus, five cases), agile gibbons (Hylobates agilis, three cases), siamangs (Hylobates syndactylus, two cases), colobus monkey (Colobus angolensis palliates, one case), argus pheasant (Argusianus argus, one case), and orangutan (Pongo pygmaeus, one case). Most species were not symptomatic; however, three symptomatic cases in Coquerel's sifakas (two) and a white handed gibbon (one) showed clinical signs of diarrhea and lethargy that resulted in death for the Coquerel's sifakas. One unexpected death also occurred in a BW ruffed lemur. To the authors' knowledge, this is the first report of YE 1B/O:8 in such a large variety of zoo species. The source of the YE could not be identified, prompting the initiation of a diseases surveillance program to prevent further cases for the species that are sensitive to YE. To date, no additional cases have been identified, thus suggesting a single introduction of the YE 1B/O:8 strain into the zoo environment. |
Culture-independent tracking of Vibrio cholerae lineages reveals complex spatiotemporal dynamics in a natural population
Kirchberger PC , Orata FD , Nasreen T , Kauffman KM , Tarr CL , Case RJ , Polz MF , Boucher YF . Environ Microbiol 2020 22 (10) 4244-4256 Populations of the bacterium Vibrio cholerae consist of dozens of distinct lineages, with primarily (but not exclusively) members of the pandemic generating (PG) lineage capable of causing the diarrheal disease cholera. Assessing composition and temporal dynamics of such populations requires extensive isolation efforts and thus only rarely covers large geographic areas or timeframes exhaustively. We developed a culture-independent amplicon sequencing strategy based on the protein-coding gene viuB (vibriobactin utilization) to study the structure of a V. cholerae population over the course of a summer. We show that the 26 co-occurring V. cholerae lineages continuously compete for limited space on nutrient-rich particles where only few of them can grow to large numbers. Differential abundance of lineages between locations and size-fractions associated with a particle-attached or free-swimming lifestyle could reflect adaptation to various environmental niches. In particular, a major V. cholerae lineage occasionally grow to large numbers on particles but remain undetectable using isolation-based methods, indicating selective culturability for some members of the species. We thus demonstrate that isolation-based studies may not accurately reflect the structure and complex dynamics of V. cholerae populations and provide a scalable high-throughput method for both epidemiological and ecological approaches to studying this species. This article is protected by copyright. All rights reserved. |
Draft Genome Sequences of Eight Vibrio sp. Clinical Isolates from across the United States That Form a Basal Sister Clade to Vibrio cholerae.
Liang K , Islam MT , Hussain N , Winkjer NS , Im MS , Rowe LA , Tarr CL , Boucher Y . Microbiol Resour Announc 2019 8 (3) We sequenced the genomes of eight isolates from various regions of the United States. These isolates form a monophyletic cluster clearly related to but distinct from Vibrio cholerae. Phylogenetic and genomic analyses suggest that they represent a basal lineage highly divergent from Vibrio cholerae or a novel species. |
Draft Genome Sequences of Nine Vibrio sp. Isolates from across the United States Closely Related to Vibrio cholerae.
Islam MT , Liang K , Im MS , Winkjer J , Busby S , Tarr CL , Boucher Y . Microbiol Resour Announc 2018 7 (21) We are reporting whole-genome sequences of nine Vibrio sp. isolates closely related to the waterborne human pathogen Vibrio cholerae. These isolates were recovered from sources, including human samples, from different regions of the United States. Genome analysis suggests that this group of isolates represents a highly divergent basal V. cholerae lineage or a closely related novel species. |
Integrated view of Vibrio cholerae in the Americas.
Domman D , Quilici ML , Dorman MJ , Njamkepo E , Mutreja A , Mather AE , Delgado G , Morales-Espinosa R , Grimont PAD , Lizarraga-Partida ML , Bouchier C , Aanensen DM , Kuri-Morales P , Tarr CL , Dougan G , Parkhill J , Campos J , Cravioto A , Weill FX , Thomson NR . Science 2017 358 (6364) 789-793 Latin America has experienced two of the largest cholera epidemics in modern history; one in 1991 and the other in 2010. However, confusion still surrounds the relationships between globally circulating pandemic Vibrio cholerae clones and local bacterial populations. We used whole-genome sequencing to characterize cholera across the Americas over a 40-year time span. We found that both epidemics were the result of intercontinental introductions of seventh pandemic El Tor V. cholerae and that at least seven lineages local to the Americas are associated with disease that differs epidemiologically from epidemic cholera. Our results consolidate historical accounts of pandemic cholera with data to show the importance of local lineages, presenting an integrated view of cholera that is important to the design of future disease control strategies. |
Complete Genome Sequence of Vibrio sp. Strain 2521-89, a Close Relative of Vibrio cholerae Isolated from Lake Water in New Mexico, USA.
Liang K , Orata FD , Winkjer NS , Rowe LA , Tarr CL , Boucher Y . Genome Announc 2017 5 (35) Vibrio sp. strain 2521-89 is an environmental isolate from lake water in New Mexico, USA. Average nucleotide identity, in silico DNA-DNA hybridization, and core genome single-nucleotide polymorphism (SNP)-based phylogenetic analysis suggest that this may be a potentially novel species that is closely related to Vibrio cholerae. |
Notes from the Field: Cronobacter sakazakii infection associated with feeding extrinsically contaminated expressed human milk to a premature infant - Pennsylvania, 2016
Bowen A , Wiesenfeld HC , Kloesz JL , Pasculle AW , Nowalk AJ , Brink L , Elliot E , Martin H , Tarr CL . MMWR Morb Mortal Wkly Rep 2017 66 (28) 761-762 In April 2016, a female infant was born via Cesarean delivery at 29 estimated gestational weeks and had a birthweight of 3 pounds (1,405 grams). Her clinical course in the neonatal intensive care unit was unremarkable until she developed signs of sepsis at age 21 days. Cultures of blood and cerebrospinal fluid yielded Cronobacter sakazakii, a gram-negative pathogenic bacillus. Despite treatment with ampicillin and cefepime, she developed seizures; brain imaging revealed liquefaction necrosis of the entire left cerebral hemisphere and right frontal lobe. The infant developed spastic cerebral palsy and global developmental delay and required a ventriculoperitoneal shunt and a gastrostomy feeding tube. | The infant had been fed pasteurized donor human milk and expressed maternal milk (EMM) during the first week after birth; thereafter, she received EMM mixed with a commercial liquid human milk fortifier. Maternal milk was expressed using a dedicated bedside hospital breast pump and the mother’s personal breast pump throughout the infant’s hospitalization. The infant did not receive powdered infant formula products. |
Whole genome and core genome multilocus sequence typing and single nucleotide polymorphism analyses of Listeria monocytogenes associated with an outbreak linked to cheese, United States, 2013.
Chen Y , Luo Y , Carleton H , Timme R , Melka D , Muruvanda T , Wang C , Kastanis G , Katz LS , Turner L , Fritzinger A , Moore T , Stones R , Blankenship J , Salter M , Parish M , Hammack TS , Evans PS , Tarr CL , Allard MW , Strain EA , Brown EW . Appl Environ Microbiol 2017 83 (15) Epidemiological findings of a listeriosis outbreak in 2013 implicated Hispanic-style cheese produced by Company A, and pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) were performed on clinical isolates and representative isolates collected from Company A cheese and environmental samples during the investigation. The results strengthened the evidence for cheese as the vehicle. Surveillance sampling and WGS three months later revealed that the equipment purchased by Company B from Company A yielded an environmental isolate highly similar to all outbreak isolates. The whole genome and core genome multilocus sequence typing and single nucleotide polymorphism (SNP) analyses were compared to demonstrate the maximum discriminatory power obtained by using multiple analyses, which were needed to differentiate outbreak-associated isolates from a PFGE-indistinguishable isolate collected in a non-implicated food source in 2012. This unrelated isolate differed from the outbreak isolates by only 7 to 14 SNPs, and as a result, minimum spanning tree by the whole genome analyses and certain variant calling approach and phylogenetic algorithm for core genome-based analyses could not provide the differentiation between unrelated isolates. Our data also suggest that SNP/allele counts should always be combined with WGS clustering generated by phylogenetically meaningful algorithms on sufficient number of isolates, and SNP/allele threshold alone is not sufficient evidence to delineate an outbreak. The putative prophages were conserved across all the outbreak isolates. All outbreak isolates belonged to clonal complex 5 and serotype 1/2b, had an identical inlA sequence, which did not have premature stop codons.IMPORTANCE In this outbreak, multiple analytical approaches were used for maximum discriminatory power. A PFGE-matched, epidemiologically unrelated isolate had high genetic similarity to the outbreak-associated isolates, with as few as only 7 SNP differences. Therefore, the SNP/allele threshold should not be used as the only evidence to define the scope of an outbreak. It is critical that the SNP/allele counts be complemented by WGS clustering generated by phylogenetically meaningful algorithms to distinguish outbreak-associated isolates from epidemiologically unrelated isolates. Careful selection of a variant calling approach and phylogenetic algorithm is critical for core genome-based analyses. The whole genome-based analyses were able to construct the highly resolved phylogeny needed to support the findings of the outbreak investigation. Ultimately, epidemiologic evidence and multiple WGS analyses should be combined to increase the confidence in outbreak investigations. |
Characterization of clinical and environmental isolates of Vibrio cidicii sp. nov., a close relative of Vibrio navarrensis.
Orata FD , Xu Y , Gladney LM , Rishishwar L , Case RJ , Boucher Y , Jordan IK , Tarr CL . Int J Syst Evol Microbiol 2016 66 (10) 4148-4155 Four Vibrio spp. isolates from the historical culture collection at the Centers for Disease Control and Prevention, obtained from human blood specimens (n = 3) and river water (n = 1), show characteristics distinct from those of isolates of the most closely related species, Vibrio navarrensis and Vibrio vulnificus, based on phenotypic and genotypic tests. They are specifically adapted to survival in both freshwater and seawater, being able to grow in rich media without added salts as well as salinities above that of seawater. Phenotypically, these isolates resemble V. navarrensis, their closest known relative with a validly published name, but the group of isolates is distinguished from V. navarrensis by the ability to utilize L-rhamnose. Average nucleotide identity and percent DNA-DNA hybridization values obtained from the pairwise comparisons of whole genome sequences of these isolates to V. navarrensis range from 95.4-95.8% and 61.9-64.3%, respectively, suggesting that the group represents a different species. Phylogenetic analysis of the core genome, including four protein-coding housekeeping genes (pyrH, recA, rpoA, and rpoB), places these four isolates into their own monophyletic clade, distinct from V. navarrensis and V. vulnificus. Based on these differences, we propose these isolates belong to a novel Vibrio species. The name Vibrio cidicii sp. nov. is proposed for these isolates; strain LMG 29267T (= CIP 111013T = 2756-81T), isolated from river water, is the type strain. |
Diversity of clinical and environmental isolates of Vibrio cholerae in natural transformation and contact-dependent bacterial killing indicative of type VI secretion system activity
Bernardy EE , Turnsek MA , Wilson SK , Tarr CL , Hammer BK . Appl Environ Microbiol 2016 82 (9) 2833-2842 The bacterial pathogen Vibrio cholerae can occupy both the human gut and aquatic reservoirs, where it may colonize chitinous surfaces that induce expression of factors for three phenotypes: chitin utilization, DNA uptake by natural transformation, and constitutive contact-dependent bacterial killing indicative of the Type VI secretion system (T6SS). In this study, we surveyed a diverse set of 53 isolates from different geographic locales collected over the past century from human clinical and environmental specimens for each phenotype outlined above. The set included pandemic isolates of serogroup O1, as well as several serogroup O139 and non-O1/non-O139 strains. We found that while chitin utilization was common, only 22.6% of all isolates tested were proficient at chitin-induced natural transformation, suggesting that transformation is expendable. Constitutive contact-dependent killing of Escherichia coli prey, which is indicative of a functional T6SS, was rare among clinical isolates (only 4 of 29) but common among environmental isolates (22 of 24). These results bolster the pathoadaptive model that tight regulation of T6SS-mediated bacterial killing is beneficial in a human host, whereas, constitutive killing by environmental isolates may give a competitive advantage in natural settings. Future sequence analysis of this set of diverse isolates may identify previously unknown regulators and structural components for both natural transformation and T6SS. |
Evolutionary Relationships of Outbreak-associated Listeria monocytogenes Strains of Serotypes 1/2a and 1/2b Determined by Whole Genome Sequencing.
Bergholz TM , den Bakker HC , Katz LS , Silk BJ , Jackson KA , Kucerova Z , Joseph LA , Turnsek M , Gladney LM , Halpin JL , Xavier K , Gossack J , Ward TJ , Frace M , Tarr CL . Appl Environ Microbiol 2015 82 (3) 928-38 We used whole genome sequencing to determine evolutionary relationships among 20 outbreak-associated clinical isolates of Listeria monocytogenes serotypes 1/2a and 1/2b. Isolates from six of eleven outbreaks fell outside of the clonal groups or 'epidemic clones' that have been previously associated with outbreaks, suggesting that epidemic potential may be widespread in L. monocytogenes and is not limited to the recognized epidemic clones. Pairwise comparisons between epidemiologically-related isolates within clonal complexes showed that genome-level variation differed by two orders of magnitude between different comparisons, and the distribution of point mutations (core versus accessory genome) also varied. In addition, genetic divergence between one closely related pair of isolates from a single outbreak was driven primarily by changes in phage regions. The evolutionary analysis showed the changes could be attributed to horizontal gene transfer; members of the diverse bacterial community found in the production facility could have served as the source of novel genetic material at some point in the production chain. The results raise the question of how to best utilize information contained within the accessory genome in outbreak investigations. The full magnitude and complexity of genetic changes revealed by genome sequencing could not be discerned from traditional subtyping methods and the results demonstrate the challenges of interpreting genetic variation among isolates recovered from a single outbreak. Epidemiological information remains critical for proper interpretation of nucleotide and structural diversity among isolates recovered during outbreaks, and will remain so until we understand more about how various population histories influence genetic variation. |
The Dynamics of Genetic Interactions Between Vibrio metoecus and Vibrio cholerae, Two Close Relatives Co-Occurring in the Environment.
Orata FD , Kirchberger PC , Meheust R , Barlow EJ , Tarr CL , Boucher Y . Genome Biol Evol 2015 7 (10) 2941-2954 Vibrio metoecus is the closest relative of Vibrio cholerae, the causative agent of the potent diarrheal disease cholera. Although the pathogenic potential of this new species is yet to be studied in depth, it has been co-isolated with V. cholerae in coastal waters and found in clinical specimens in the USA. We used these two organisms to investigate the genetic interaction between closely related species in their natural environment. The genomes of twenty V. cholerae and four V. metoecus strains isolated from a brackish coastal pond on the US east coast, as well as four clinical V. metoecus strains were sequenced and compared to reference strains. Whole genome comparison shows 86-87% average nucleotide identity (ANI) in their core genes between the two species. On the other hand, the chromosomal integron, which occupies approximately 3% of their genomes, shows higher conservation in ANI between species than any other region of their genomes. The ANI of 93-94% observed in this region is not significantly greater within than between species, meaning that it does not follow species boundaries. V. metoecus does not encode toxigenic V. cholerae major virulence factors, the cholera toxin and toxin co-regulated pilus. However, some of the pathogenicity islands found in pandemic V. cholerae were either present in the common ancestor it shares with V. metoecus, or acquired by clinical and environmental V. metoecus in partial fragments. The virulence factors of V. cholerae are therefore both more ancient and more widespread than previously believed. There is high interspecies recombination in the core genome, which has been detected in 24% of the single-copy core genes, including genes involved in pathogenicity. V. metoecus was six times more often the recipient of DNA from V. cholerae as it was the donor, indicating a strong bias in the direction of gene transfer in the environment. |
Phylodynamic analysis of clinical and environmental Vibrio cholerae isolates from Haiti reveals diversification driven by positive selection.
Azarian T , Ali A , Johnson JA , Mohr D , Prosperi M , Veras NM , Jubair M , Strickland SL , Rashid MH , Alam MT , Weppelmann TA , Katz LS , Tarr CL , Colwell RR , Morris JG Jr , Salemi M . mBio 2014 5 (6) 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. |
Genome Sequences of Vibrio navarrensis, a Potential Human Pathogen.
Gladney LM , Katz LS , Knipe KM , Rowe LA , Conley AB , Rishishwar L , Marino-Ramirez L , Jordan IK , Tarr CL . Genome Announc 2014 2 (6) Vibrio navarrensis is an aquatic bacterium recently shown to be associated with human illness. We report the first genome sequences of three V. navarrensis strains obtained from clinical and environmental sources. Preliminary analyses of the sequences reveal that V. navarrensis contains genes commonly associated with virulence in other human pathogens. |
Environmental surveillance for toxigenic Vibrio cholerae in surface waters of Haiti.
Kahler AM , Haley BJ , Chen A , Mull BJ , Tarr CL , Turnsek M , Katz LS , Humphrys MS , Derado G , Freeman N , Boncy J , Colwell RR , Huq A , Hill VR . Am J Trop Med Hyg 2014 92 (1) 118-25 Epidemic cholera was reported in Haiti in 2010, with no information available on the occurrence or geographic distribution of toxigenic Vibrio cholerae in Haitian waters. In a series of field visits conducted in Haiti between 2011 and 2013, water and plankton samples were collected at 19 sites. Vibrio cholerae was detected using culture, polymerase chain reaction, and direct viable count methods (DFA-DVC). Cholera toxin genes were detected by polymerase chain reaction in broth enrichments of samples collected in all visits except March 2012. Toxigenic V. cholerae was isolated from river water in 2011 and 2013. Whole genome sequencing revealed that these isolates were a match to the outbreak strain. The DFA-DVC tests were positive for V. cholerae O1 in plankton samples collected from multiple sites. Results of this survey show that toxigenic V. cholerae could be recovered from surface waters in Haiti more than 2 years after the onset of the epidemic. |
Molecular and phenotypic characterization of Vibrio navarrensis isolates associated with human illness.
Gladney LM , Tarr CL . J Clin Microbiol 2014 52 (11) 4070-4 We characterized 18 Vibrio isolates, including 15 recovered from human clinical specimens and found that they clustered with two previously characterized V. navarrensis isolates in a phylogenetic analysis. Four of the 18 strains may represent a new Vibrio species, distinct from V. navarrensis. The potential role of V. navarrensis in human disease needs further investigation. |
Draft Genome Sequence of Environmental Vibrio cholerae 2012EL-1759 with Similarities to the V. cholerae O1 Classical Biotype.
Katz LS , Turnsek M , Kahler A , Hill VR , Boyd EF , Tarr CL . Genome Announc 2014 2 (4) Vibrio cholerae 2012EL-1759 is an environmental isolate from Haiti that was recovered in 2012 during a cholera outbreak. The genomic backbone is similar to that of the prototypical V. cholerae O1 classical biotype strain O395, and it carries the Vibrio pathogenicity islands (VPI-1 and VPI-2) and a cholera toxin (CTX) prephage. |
Vibrio metoecus sp.nov., a close relative of Vibrio cholerae isolated from coastal brackish ponds and clinical specimens
Kirchberger PC , Turnsek M , Hunt DE , Haley BJ , Colwell RR , Polz MF , Tarr CL , Boucher Y . Int J Syst Evol Microbiol 2014 64 3208-3214 A Gram staining negative, curved rod shaped bacterium with close resemblance to Vibrio cholerae, the etiological agent of cholera, was isolated over the course of several years from coastal brackish water (17 strains) and from clinical cases (two strains) in the United States. 16S rRNA gene identity with V. cholerae exceeds 98% yet an average nucleotide identity of around 86% and multi locus sequence analysis of six housekeeping genes (mdh, adk, gyrB, recA, pgi, rpoB) clearly delineates these isolates as a distinct genotypic cluster within the V. cholerae-V. mimicus clade. Most standard identification techniques do not differentiate this cluster of isolates from V. cholerae. Only amplification of the ompW gene using V. cholerae-specific primers and a negative Voges-Proskauer test shows a difference between the two clusters. Additionally, all isolated strains differ phenotypically from V. cholerae in their ability to utilize N-Acetyl-d-galactosamine and d-glucuronic acid as sole carbon sources. Furthermore, they are generally unable to infect the slime mold Dictyostelium discoideum, a widespread ability in V. cholerae. Based on these clear phenotypic differences that are not necessarily apparent in standard tests and, average nucleotide identity and phylogeny of protein-coding genes, we propose the existence of a new species, Vibrio metoecus sp. nov. with the type strain OP3H (LMG 27764, CIP 110643T). Due to its close resemblance to V. cholerae and the increasing number of strains isolated over the past several years, we suggest that V. metoecus sp. nov. is a relatively common Vibrio species that has been identified as atypical isolates of V. cholerae in the past. Its isolation from clinical samples also suggests strains of this species, like V. cholerae, are opportunistic pathogens. |
Population structure of Listeria monocytogenes serotype 4b isolates from sporadic human listeriosis cases in the United States from 2003 to 2008.
Lee S , Ward TJ , Graves LM , Tarr CL , Siletzky RM , Kathariou S . Appl Environ Microbiol 2014 80 (12) 3632-44 Listeria monocytogenes can cause severe foodborne disease (listeriosis). Numerous outbreaks have involved three serotype 4b epidemic clones (ECs): ECI, ECII and ECIa. However, little is known about the population structure of L. monocytogenes serotype 4b from sporadic listeriosis in the United States, even though most cases of human listeriosis are in fact sporadic. Here we analyzed 136 serotype 4b isolates from sporadic cases in the United States, 2003-2008, utilizing multiple tools including multilocus genotyping, pulsed-field gel electrophoresis and sequence analysis of the inlAB locus. ECI, ECII and ECIa were frequently encountered (32, 17 and 7%, respectively). However, annually 30-68% of isolates were outside of these ECs and several novel clonal groups were identified. An estimated 33 and 17% of the isolates, mostly among the ECs, were resistant to cadmium and arsenic, respectively, but resistance to benzalkonium chloride was uncommon (3%) among the sporadic isolates. Frequency of clonal groups fluctuated within the six-year study period, without consistent trends. However, on several occasions, temporal clusters of isolates with indistinguishable genotypes were detected, suggesting the possibility of hidden multistate outbreaks. Our analysis suggests a complex population structure of serotype 4b L. monocytogenes from sporadic disease, with important contributions by ECs and several novel clonal groups. Continuous monitoring will be needed to assess long term trends in clonality patterns and population structure of L. monocytogenes from sporadic listeriosis. |
Evolutionary dynamics of Vibrio cholerae O1 following a single-source introduction to Haiti
Katz LS , Petkau A , Beaulaurier J , Tyler S , Antonova ES , Turnsek MA , Guo Y , Wang S , Paxinos EE , Orata F , Gladney LM , Stroika S , Folster JP , Rowe L , Freeman MM , Knox N , Frace M , Boncy J , Graham M , Hammer BK , Boucher Y , Bashir A , Hanage WP , Van Domselaar G , Tarr CL . mBio 2013 4 (4) Prior to the epidemic that emerged in Haiti in October of 2010, cholera had not been documented in this country. After its introduction, a strain of Vibrio cholerae O1 spread rapidly throughout Haiti, where it caused over 600,000 cases of disease and >7,500 deaths in the first two years of the epidemic. We applied whole-genome sequencing to a temporal series of V. cholerae isolates from Haiti to gain insight into the mode and tempo of evolution in this isolated population of V. cholerae O1. Phylogenetic and Bayesian analyses supported the hypothesis that all isolates in the sample set diverged from a common ancestor within a time frame that is consistent with epidemiological observations. A pangenome analysis showed nearly homogeneous genomic content, with no evidence of gene acquisition among Haiti isolates. Nine nearly closed genomes assembled from continuous-long-read data showed evidence of genome rearrangements and supported the observation of no gene acquisition among isolates. Thus, intrinsic mutational processes can account for virtually all of the observed genetic polymorphism, with no demonstrable contribution from horizontal gene transfer (HGT). Consistent with this, the 12 Haiti isolates tested by laboratory HGT assays were severely impaired for transformation, although unlike previously characterized noncompetent V. cholerae isolates, each expressed hapR and possessed a functional quorum-sensing system. Continued monitoring of V. cholerae in Haiti will illuminate the processes influencing the origin and fate of genome variants, which will facilitate interpretation of genetic variation in future epidemics. IMPORTANCE Vibrio cholerae is the cause of substantial morbidity and mortality worldwide, with over three million cases of disease each year. An understanding of the mode and rate of evolutionary change is critical for proper interpretation of genome sequence data and attribution of outbreak sources. The Haiti epidemic provides an unprecedented opportunity to study an isolated, single-source outbreak of Vibrio cholerae O1 over an established time frame. By using multiple approaches to assay genetic variation, we found no evidence that the Haiti strain has acquired any genes by horizontal gene transfer, an observation that led us to discover that it is also poorly transformable. We have found no evidence that environmental strains have played a role in the evolution of the outbreak strain. |
Genomic characterization of Listeria monocytogenes strains involved in a multistate listeriosis outbreak associated with cantaloupe in US.
Laksanalamai P , Joseph LA , Silk BJ , Burall LS , Tarr CL , Gerner-Smidt P , Datta AR . PLoS One 2012 7 (7) e42448 A multistate listeriosis outbreak associated with cantaloupe consumption was reported in the United States in September, 2011. The outbreak investigation recorded a total of 146 invasive illnesses, 30 deaths and one miscarriage. Subtyping of the outbreak associated clinical, food and environmental isolates revealed two serotypes (1/2a and 1/2b) and four pulsed-field gel electrophoresis two-enzyme pattern combinations I, II, III, and IV, including one rarely seen before this outbreak. A DNA-microarray, Listeria GeneChip(R), developed by FDA from 24 Listeria monocytogenes genome sequences, was used to further characterize a representative sample of the outbreak isolates. The microarray data (in the form of present or absent calls of specific DNA sequences) separated the isolates into two distinct groups as per their serotypes. The gene content of the outbreak-associated isolates was distinct from that of the previously-reported outbreak strains belonging to the same serotypes. Although the 1/2b outbreak associated isolates are closely related to each other, the 1/2a isolates could be further divided into two distinct genomic groups, one represented by pattern combination I strains and the other represented by highly similar pattern combinations III and IV strains. Gene content analysis of these groups revealed unique genomic sequences associated with these two 1/2a genovars. This work underscores the utility of multiple approaches, such as serotyping, PFGE and DNA microarray analysis to characterize the composition of complex polyclonal listeriosis outbreaks. |
A hybrid approach for the automated finishing of bacterial genomes.
Bashir A , Klammer AA , Robins WP , Chin CS , Webster D , Paxinos E , Hsu D , Ashby M , Wang S , Peluso P , Sebra R , Sorenson J , Bullard J , Yen J , Valdovino M , Mollova E , Luong K , Lin S , Lamay B , Joshi A , Rowe L , Frace M , Tarr CL , Turnsek M , Davis BM , Kasarskis A , Mekalanos JJ , Waldor MK , Schadt EE . Nat Biotechnol 2012 30 (7) 701-707 Advances in DNA sequencing technology have improved our ability to characterize most genomic diversity. However, accurate resolution of large structural events is challenging because of the short read lengths of second-generation technologies. Third-generation sequencing technologies, which can yield longer multikilobase reads, have the potential to address limitations associated with genome assembly. Here we combine sequencing data from second- and third-generation DNA sequencing technologies to assemble the two-chromosome genome of a recent Haitian cholera outbreak strain into two nearly finished contigs at >99.9% accuracy. Complex regions with clinically relevant structure were completely resolved. In separate control assemblies on experimental and simulated data for the canonical N16961 cholera reference strain, we obtained 14 scaffolds of greater than 1 kb for the experimental data and 8 scaffolds of greater than 1 kb for the simulated data, which allowed us to correct several errors in contigs assembled from the short-read data alone. This work provides a blueprint for the next generation of rapid microbial identification and full-genome assembly. |
Toxigenic Vibrio cholerae O1 in water and seafood, Haiti
Hill VR , Cohen N , Kahler AM , Jones JL , Bopp CA , Marano N , Tarr CL , Garrett NM , Boncy J , Henry A , Gomez GA , Wellman M , Curtis M , Freeman MM , Turnsek M , Benner RA Jr , Dahourou G , Espey D , DePaola A , Tappero JW , Handzel T , Tauxe RV . Emerg Infect Dis 2011 17 (11) 2147-2150 During the 2010 cholera outbreak in Haiti, water and seafood samples were collected to detect Vibrio cholerae. The outbreak strain of toxigenic V. cholerae O1 serotype Ogawa was isolated from freshwater and seafood samples. The cholera toxin gene was detected in harbor water samples. |
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