Diversity Of Spirochetes Research Articles

"Candidatus Borrelia ibitipoquensis," a Borrelia valaisiana-Related Genospecies Characterized from Ixodes paranaensis in Brazil.

Borrelia burgdorferi sensu lato (Bbsl) spirochetes include the agents of Lyme borreliosis in temperate regions of the Northern Hemisphere, and merge their transmission cycles mainly with ticks of the Ixodes ricinus complex. Twenty genospecies compose Bbsl currently, and with the exception of Borrelia chilensis, and Borrelia garinii, all have been described only for North America, Europe, North Africa, and Asia. Here, we collected specimens of Ixodes paranaensis, a tick associated with swifts in a Brazilian natural park from the state of Minas Gerais, and performed a molecular characterization of 11 borrelial genes. Based on comparisons of inter and intraspecific genetic divergences, and Bayesian phylogenetic trees inferred for 16S rRNA, flaB, p66, and concatenated clpA, clpX, pepX, pyrG, recG, nifS rlpB, and uvrA genes, we demonstrate the occurrence of a new genospecies of Bbsl. "Candidatus Borrelia ibitipoquensis" Ip37 is closely related to Borrelia sp. Am501, and Borrelia valaisiana, a spirochete transmitted by ticks of the I. ricinus complex in Eurasia that uses birds as reservoirs. In a similar ecological scenario involving ticks and avian hosts, the migratory swift Streptoprocne biscutata is the sole-documented bird associated with I. paranaensis, and, although not assessed in this study, could correspond to the vertebrate reservoir of this newly described genospecies in Brazil. Pathogenic roles of "Ca. B. ibitipoquensis" are still unknown. However, its possible vector I. paranaensis is not an anthropophilic tick, so human infections would be unlikely to occur. Our finding enhances the knowledge on Bbsl in South America, highlights the occurrence of ecologically and genetically related genospecies with vastly separated geographical distributions, and calls for the attention to explore a barely known diversity of spirochetes of this group in the region.

Circulation of Tick-Borne Spirochetes in Tick and Small Mammal Communities in Santa Barbara County, California, USA.

A diversity of Borrelia burgdorferi sensu lato (Johnson, Schmid, Hyde, Steigerwalt & Brenner) (Spirochaetales: Spirochaetaceae) genomospecies, including the Lyme disease agent, Borrelia burgdorferi sensu stricto (s.s.), have been identified in the western United States. However, enzootic transmission of B. burgdorferi s.l. in small mammals and ticks is poorly characterized throughout much of the region. Here we report prevalence of B. burgdorferi s.l. in small mammal and tick communities in the understudied region of southern California. We found B. burgdorferi s.l. in 1.5% of Ixodes species ticks and 3.6% of small mammals. Infection was uncommon (~0.3%) in Ixodes pacificus Cooley and Kohls (Acari: Ixodidae), the primary vector of the Lyme disease agent to humans in western North America, but a diversity of spirochetes-including Borrelia bissettiae, Borrelia californiensis, Borrelia americana, and B. burgdorferi s.s.-were identified circulating in Ixodes species ticks and their small mammal hosts. Infection with B. burgdorferi s.l. is more common in coastal habitats, where a greater diversity of Ixodes species ticks are found feeding on small mammal hosts (four species when compared with only I. pacificus in other sampled habitats). This provides some preliminary evidence that in southern California, wetter coastal areas might be more favorable for enzootic transmission than hotter and drier climates. Infection patterns confirm that human transmission risk of B. burgdorferi s.s. is low in this region. However, given evidence for local maintenance of B. burgdorferi s.l., more studies of enzootic transmission may be warranted, particularly in understudied regions where the tick vector of B. burgdorferi s.s. occurs.

Infection history of the blood-meal host dictates pathogenic potential of the Lyme disease spirochete within the feeding tick vector.

Lyme disease in humans is caused by several genospecies of the Borrelia burgdorferi sensu lato (s.l.) complex of spirochetal bacteria, including B. burgdorferi, B. afzelii and B. garinii. These bacteria exist in nature as obligate parasites in an enzootic cycle between small vertebrate hosts and Ixodid tick vectors, with humans representing incidental hosts. During the natural enzootic cycle, infected ticks in endemic areas feed not only upon naïve hosts, but also upon seropositive infected hosts. In the current study, we considered this environmental parameter and assessed the impact of the immune status of the blood-meal host on the phenotype of the Lyme disease spirochete within the tick vector. We found that blood from a seropositive host profoundly attenuates the infectivity (>104 fold) of homologous spirochetes within the tick vector without killing them. This dramatic neutralization of vector-borne spirochetes was not observed, however, when ticks and blood-meal hosts carried heterologous B. burgdorferi s.l. strains, or when mice lacking humoral immunity replaced wild-type mice as blood-meal hosts in similar experiments. Mechanistically, serum-mediated neutralization does not block induction of host-adapted OspC+ spirochetes during tick feeding, nor require tick midgut components. Significantly, this study demonstrates that strain-specific antibodies elicited by B. burgdorferi s.l. infection neutralize homologous bacteria within feeding ticks, before the Lyme disease spirochetes enter a host. The blood meal ingested from an infected host thereby prevents super-infection by homologous spirochetes, while facilitating transmission of heterologous B. burgdorferi s.l. strains. This finding suggests that Lyme disease spirochete diversity is stably maintained within endemic populations in local geographic regions through frequency-dependent selection of rare alleles of dominant polymorphic surface antigens.

Lyme Borreliosis in Europe and North America: Epidemiology and Clinical Practice

The title of this book surprises with the term “Lyme borreliosis,” which is rarely used in publications from the United States. Nevertheless, the specific term Lyme borreliosis is justified because it names a disease caused by particular infectious organisms, Borrelia burgdorferi sensu lato, whereas the term “Lyme disease” described a disease without a known cause and is now applied to a broad spectrum of symptoms where the infectious agent is not demonstrable (ie, chronic Lyme disease). Subsequently, Lyme disease and Lyme borreliosis have gained a high degree of prominence. Therefore, a book that deals with all aspects of the disease on evidence-based grounds written by authors who are well established in the field of clinical Lyme borreliosis is very welcome. Lyme Borreliosis in Europe and North America consists of 12 chapters. All chapters are substantiated by a series of references. Chapter 1 introduces historical details and epidemiology. The discovery of the Lyme spirochetes also made a great impact in Europe where clinical manifestations such as erythema chronicum migrans, benign lymphadenosis cutis, acrodermatitis chronic atrophicans (ACA), and Garin-Bujadoux-Bannwarth syndrome had been described previously and are now known to form a nosological entity of borrelial origin. Chapter 2 deals with the diversity of spirochetes, tick ecology, tick maintenance hosts, and spirochete reservoir hosts. It describes how the complex ecology underpinning the circulation of the spirochetes in nature depends on factors that maintain both tick populations and the vertebrate reservoirs of B. burgdorferi sensu lato. In chapter 3, “Early Lyme Borreliosis,” the authors refreshingly reject the stages of Lyme borreliosis that do not correlate with clinical experience. The more flexible descriptive terminology is recommended— namely, early localized, early disseminated, and late disease. Erythema migrans, the most frequent manifestation of Lyme borreliosis, is described in its various appearances. These are illustrated by many photographs, also given in an insert for color representation. The primarily clinical diagnosis of erythema migrans consequently requires a broad understanding of the various clinical presentations and of the differential diagnoses. In chapter 4, “Lyme Carditis,” the problems with the specific diagnosis of cardiac manifestations are described. The authors recommend caution particularly in fatal outcomes because of the difficulty of excluding the role of comorbidity. Chapter 5, “Nervous System Lyme Borreliosis,” clearly describes an approach to diagnosis, lists the relevant findings in the cerebrospinal fluid, and presents the clinical spectrum of Lyme neuroborreliosis. Prognosis and outcome after treatment with adequate antibiotics are evaluated extremely well. In chapter 6, “Lyme Arthritis,” the possible pathophysiological processes that may lead to antibiotic-resistant Lyme arthritis are described. Because clinical presentation of Lyme arthritis is not different from other inflammatory arthritides, it should be considered within the differential diagnosis of any arthritic condition. Dosages and duration for treatment of Lyme arthritis are supported only by a small number of clinical trials. Borrelial lymphocytoma and ACA, discussed in chapter 7, are considered to be more or less restricted to Europe, and are extremely rare manifestations in North America. Coinfection with Anaplasma phagocytophilum or Babesia species (chapter 8) may occur and may result in a severe course of disease. Although such interactions are rarely observed, they should be taken into consideration if patients present with fever, chills, and severe headache. Chapters 9 and 10 deal with the direct and indirect detection of B. burgdorferi sensu lato in human disease. Success of cultivation is best from skin specimens of erythema migrans and ACA and from plasma blood samples of US patients with erythema migrans. Sensitivity of polymerase chain reaction is similar in these manifestations. Serodiagnosis offers a simpler way to collect samples, perform testing, and achieve results in a short period of time to detect specific antibodies. Two-tiered serology and performance characteristics of tests are described, and the implications for serodiagnosis of the heterogeneity of B. burgdorferi sensu lato in Europe, newer assays, and future directions are discussed. The reader will learn about the role and usage of laboratory results for diagnosing Lyme borreliosis, including the avoidance of misinterpretation. Chapter 11 on prognosis deals with shortand long-term outcomes. Observational studies suggest that the prognosis is excellent. The editor himself is the single author of the last chapter, “Prevention of Lyme Borreliosis.” It deals with all available aspects including prevention of exposure, control Clinical Infectious Diseases 2013;56(9):1360–1 © The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/cid/cit077

Spirochetes in gastropods from Lake Baikal and North American freshwaters: new multi-family, multi-habitat host records

We describe the first records of spirochetes in the gut of fourteen species of continental gastropods from a range of habitats and representing six families (Amnicolidae, Baicaliidae, Bithyniidae, Pyrgulidae, Lithoglyphidae and Benedictiidae). The bacteria were mainly found in the crystalline style sac, as has been reported in marine bivalves. The surveyed habitats include water bodies in North America and Eurasia, including deep water hydrothermal vent and gas hydrate zones in Lake Baikal. Spirochetes were present both in mature and young snails, but were not detected in embryos before hatching, indicating lateral transfer. The surveyed gastropods range in trophic strategy, including phyto-, detrito- and bacteriophagous grazers and filter feeders. Our results indicate that spirochetes are commensal in the surveyed gastropods with potential limited benefit and no detriment to the host animal. We suggest that the specialized internal habitat of the crystalline style sac in molluscs is likely to reveal unrecognized spirochete diversity that will shed new light on gastropod trophic ecology and spirochete diversity.

Spirochetes in Crystalline Styles of Marine Bivalves: Group-Specific PCR Detection and 16S rRNA Sequence Analysis

Although spirochetes were first detected in crystalline styles of bivalves more than 100 years ago, little is known about the characteristics of these consortia (commensalism or parasitism). The presence of spirochetes in bivalves can so far not be generalized. The purpose of this study was the detection and phylogenetic identification of spirochetes associated with crystalline styles of different marine bivalve species collected in temperate regions and Antarctica. Polymerase chain reaction amplification of spirochete 16S ribosomal gene sequences was performed. 16S ribosomal gene clones were identified by phylogenetic analysis, and the variability within each bivalve species was determined. The spirochetes were mainly related to yet uncultured or potentially pathogenic spirochetes from the marine environment. All identified spirochete clones fell into 2 families: the Spirochaetaceae with 2 genera, Cristispira and Spirochaeta, and the Brachyspiraceae, with the genus Braehyspira. The diversity of spirochetes in the crystalline style of each bivalve species was low. All clone sequences from crystalline styles of the oyster Crassostrea gigas clustered into the group of Cristispira species. Interestingly, these Cristispira spirochetes were previously found in Crassostrea virginica, another oyster species. The spirochete clones of each bivalve species formed distinct clusters. We therefore assume that the investigated bivalve species harbor distinct populations of spirochetes. Although spirochetes were not found in all the investigated samples, the occurrence of spirochetes was not random and implies a closer association between the bivalve species and the specific spirochete cluster.

Population Structure of the Lyme Borreliosis Spirochete Borrelia burgdorferi in the Western Black-Legged Tick ( Ixodes pacificus ) in Northern California

Factors potentially contributing to the lower incidence of Lyme borreliosis (LB) in the far-western than in the northeastern United States include tick host-seeking behavior resulting in fewer human tick encounters, lower densities of Borrelia burgdorferi-infected vector ticks in peridomestic environments, and genetic variation among B. burgdorferi spirochetes to which humans are exposed. We determined the population structure of B. burgdorferi in over 200 infected nymphs of the primary bridging vector to humans, Ixodes pacificus, collected in Mendocino County, CA. This was accomplished by sequence typing the spirochete lipoprotein ospC and the 16S-23S rRNA intergenic spacer (IGS). Thirteen ospC alleles belonging to 12 genotypes were found in California, and the two most abundant, ospC genotypes H3 and E3, have not been detected in ticks in the Northeast. The most prevalent ospC and IGS biallelic profile in the population, found in about 22% of ticks, was a new B. burgdorferi strain defined by ospC genotype H3. Eight of the most common ospC genotypes in the northeastern United States, including genotypes I and K that are associated with disseminated human infections, were absent in Mendocino County nymphs. ospC H3 was associated with hardwood-dominated habitats where western gray squirrels, the reservoir host, are commonly infected with LB spirochetes. The differences in B. burgdorferi population structure in California ticks compared to the Northeast emphasize the need for a greater understanding of the genetic diversity of spirochetes infecting California LB patients.

Diversity of Spirochetes in Endodontic Infections

The diversity of spirochetes in primary endodontic infections of teeth with chronic apical periodontitis or acute apical abscesses was investigated using 16S rRNA gene clone library analysis. The prevalences of three common cultivable oral Treponema species were also determined using species-specific nested PCR. All detected spirochetes belonged to the genus Treponema. Overall, 28 different taxa were identified from the 431 clones sequenced: 9 cultivable and validly named species, 1 cultivable as-yet-uncharacterized strain, and 18 as-yet-uncultivated phylotypes, 17 of which were novel. The large majority of clones (94%) were from cultivable named species. The numbers of Treponema species/phylotypes per selected positive sample ranged from 2 to 12. Species-specific nested PCR detected T. denticola, T. socranskii, and T. maltophilum in 59 (66%), 33 (37%), and 26 (29%) of the 90 cases of primary endodontic infections, respectively. Clone library analysis revealed diverse Treponema species/phylotypes as part of the microbiota associated with asymptomatic and symptomatic (abscess) endodontic infections. Although several as-yet-uncultivated Treponema phylotypes were disclosed, including novel taxa, cultivable named species were more abundant and frequently detected.

Coevolution of symbiotic spirochete diversity in lower termites.

The phylogenetic relationships of symbiotic spirochetes from five dry-wood feeding lower termites (Cryptotermes cavifrons, Heterotermes tenuis, Kalotermes flavicollis, Neotermes mona, and Reticulitermes grassei) was compared to those described in previous reports. The 16S rDNA bacterial genes were PCR-amplified from DNA isolated from intestinal samples using a spirochete-selective primer, and the 16S amplicons were cloned into Escherichia coli. Sequences of the cloned inserts were then used to determine closest relatives by comparison with published sequences. Clones sharing more than 97% sequence identity were grouped into the same phylotype. Forty-three new phylotypes were identified. These termite whole-gut-spirochetes fell into two previous defined clusters, designated as Treponema Clusters I and II, and one new Cluster III. Thirty-seven phylotypes were grouped in Cluster I. Cluster II comprised three phylotypes, two from Reticulitermes grassei (LJ029 and LJ012) and one from Heterotermes tenuis (LQ016). Three phylotypes, LK057, LK050 and LK028, were affiliated to Cluster III. Members of Cluster I showed the following characteristics: (i) spirochete phylotypes from a particular species of termite were more closely related to each other than to phylotypes of other termite species; (ii) spirochetes obtained from different genera of the same family, such as Cryptotermes sp., Kalotermes sp., and Neotermes sp., all from the family Kalotermitidae, were also related to each other. It was therefore concluded that spirochetes are specific symbionts that have coevolved with their respective species of termites, are stably harbored, and are closely related to members of the same termite family.

Genetic Diversity of Borrelia burgdorferi Sensu Stricto in Peromyscus leucopus , the Primary Reservoir of Lyme Disease in a Region of Endemicity in Southern Maryland

In the north central and northeastern United States, Borrelia burgdorferi sensu stricto, the etiologic agent of Lyme disease (LD), is maintained in an enzootic cycle between the vector, Ixodes scapularis, and the primary reservoir host, Peromyscus leucopus. Genetic diversity of the pathogen based on sequencing of two plasmid-located genes, those for outer surface protein A (ospA) and outer surface protein C (ospC), has been examined in both tick and human specimens at local, regional, and worldwide population scales. Additionally, previous studies have only been conducted with tick or human specimens at the local population level in areas with high LD transmission rates. This study examined the genetic diversity of circulating borreliae in the reservoir population from a large region of the western coastal plains of southern Maryland, where moderate numbers of human LD cases are reported. Six ospA mobility classes, including two that were not previously described, and eight ospC groups were found among the P. leucopus samples. Twenty-five percent of all specimens were infected with more than one ospA or ospC variant. The frequency distribution of variants was homogeneous, both locally and spatially. The spirochete diversity found in Maryland was not as high as that observed among northern tick populations, yet similar genotypes were observed in both populations. These results also show that mice are important for maintaining Borrelia variants, even rare variants, and that reservoir populations should therefore be considered when assessing the diversity of B. burgdorferi.

The diversity of periodontal spirochetes by 16S rRNA analysis.

The purpose of this study was to examine the diversity of spirochetes in the subgingival pocket of multiple subjects with a range of periodontal conditions, including two healthy, one adult periodontitis, three acute necrotizing ulcerative gingivitis, eight refractory periodontitis, and one human immunodeficiency virus (HIV) periodontitis. The 16S rRNA genes of spirochetes in plaque were amplified by polymerase chain reaction using spirochete selective primers. Over 500 clones were sequenced and subjected to phylogenetic analysis. The sequences clustered into the 10 known cultivated Treponema species and into 47 as-yet-uncultivated Treponema species. Most of these Treponema species were identified from multiple clones and subjects. The human periodontal pocket harbors a highly diverse treponeme population. Of the cultivated species, Treponema denticola, Treponema maltophilum and Treponema sp. Smibert-3 were most commonly encountered in diseased subjects but rarely in healthy subjects. Molecular tools based on the sequence data from this study will allow determination of the prevalence of cultivable and uncultivable treponemes in oral diseases.

Etiology of the acrodermatitis chronica atrophicans lesion in Lyme disease.

Spirochete diversity in acrodermatitis chronica atrophicans lesions in a closely defined central European site was compared to that in the local vector population, in human erythema migrans lesions, and in cerebrospinal fluid by amplifying and sequencing a segment of the gene of outer surface protein A directly from sampled tissues. Borrelia garinii, Borrelia afzelii, and Borrelia burgdorferi acutely infect human skin and invade internal tissues. Only B. afzelii, however, is associated with acrodermatitis chronica atrophicans lesions, persisting chronically where the skin has atrophied.