In the past decade, leptospirosis has emerged as a globally important infectious disease. It occurs in urban environments of industrialised and developing countries, as well as in rural regions worldwide. Mortality remains significant, related both to delays in diagnosis due to lack of infrastructure and adequate clinical suspicion, and to other poorly understood reasons that may include inherent pathogenicity of some leptospiral strains or genetically determined host immunopathological responses. Pulmonary haemorrhage is recognised increasingly as a major, often lethal, manifestation of leptospirosis, the pathogenesis of which remains unclear. The completion of the genome sequence of Leptospira interrogans serovar lai, and other continuing leptospiral genome sequencing projects, promise to guide future work on the disease. Mainstays of treatment are still tetracyclines and beta-lactam/cephalosporins. No vaccine is available. Prevention is largely dependent on sanitation measures that may be difficult to implement, especially in developing countries.

https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(03)00830-2.pdf

Leptospirosis: a zoonotic disease of global importance

The genome of the bacterium Borrelia burgdorferi B31, the aetiologic agent of Lyme disease, contains a linear chromosome of 910,725 base pairs and at least 17 linear and circular plasmids with a combined size of more than 533,000 base pairs. The chromosome contains 853 genes encoding a basic set of proteins for DNA replication, transcription, translation, solute transport and energy metabolism, but, like Mycoplasma genitalium, it contains no genes for cellular biosynthetic reactions. Because B. burgdorferi and M. genitalium are distantly related eubacteria, we suggest that their limited metabolic capacities reflect convergent evolution by gene loss from more metabolically competent progenitors. Of 430 genes on 11 plasmids, most have no known biological function; 39% of plasmid genes are paralogues that form 47 gene families. The biological significance of the multiple plasmid-encoded genes is not clear, although they may be involved in antigenic variation or immune evasion.

/pdf/genomic-sequence-of-a-lyme-disease-spirochaete-borrelia-44aw2zgpvd.pdf

Genomic sequence of a Lyme disease spirochaete, Borrelia burgdorferi

Global energy and environmental problems have stimulated increased efforts towards synthesizing biofuels from renewable resources. Compared to the traditional biofuel, ethanol, higher alcohols offer advantages as gasoline substitutes because of their higher energy density and lower hygroscopicity. In addition, branched-chain alcohols have higher octane numbers compared with their straight-chain counterparts. However, these alcohols cannot be synthesized economically using native organisms. Here we present a metabolic engineering approach using Escherichia coli to produce higher alcohols including isobutanol, 1-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol and 2-phenylethanol from glucose, a renewable carbon source. This strategy uses the host's highly active amino acid biosynthetic pathway and diverts its 2-keto acid intermediates for alcohol synthesis. In particular, we have achieved high-yield, high-specificity production of isobutanol from glucose. The strategy enables the exploration of biofuels beyond those naturally accumulated to high quantities in microbial fermentation.

Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels

Evidence-based guidelines for the management of patients with Lyme disease, human granulocytic anaplasmosis (formerly known as human granulocytic ehrlichiosis), and babesiosis were prepared by an expert panel of the Infectious Diseases Society of America. These updated guidelines replace the previous treatment guidelines published in 2000 (Clin Infect Dis 2000; 31[Suppl 1]:1-14). The guidelines are intended for use by health care providers who care for patients who either have these infections or may be at risk for them. For each of these Ixodes tickborne infections, information is provided about prevention, epidemiology, clinical manifestations, diagnosis, and treatment. Tables list the doses and durations of antimicrobial therapy recommended for treatment and prevention of Lyme disease and provide a partial list of therapies to be avoided. A definition of post-Lyme disease syndrome is proposed.

/pdf/the-clinical-assessment-treatment-and-prevention-of-lyme-xajvcef2ye.pdf

The Clinical Assessment, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: Clinical Practice Guidelines by the Infectious Diseases Society of America

Insulin resistance is a forerunner state of ischaemic cardiovascular disease and type 2 diabetes. Here we show how the human gut microbiome impacts the serum metabolome and associates with insulin resistance in 277 non-diabetic Danish individuals. The serum metabolome of insulin-resistant individuals is characterized by increased levels of branched-chain amino acids (BCAAs), which correlate with a gut microbiome that has an enriched biosynthetic potential for BCAAs and is deprived of genes encoding bacterial inward transporters for these amino acids. Prevotella copri and Bacteroides vulgatus are identified as the main species driving the association between biosynthesis of BCAAs and insulin resistance, and in mice we demonstrate that P. copri can induce insulin resistance, aggravate glucose intolerance and augment circulating levels of BCAAs. Our findings suggest that microbial targets may have the potential to diminish insulin resistance and reduce the incidence of common metabolic and cardiovascular disorders.

Human gut microbes impact host serum metabolome and insulin sensitivity

A review of reports on the genetic and phenotypic characteristics of strains of the spirochete which causes Lyme disease revealed that these organisms are representative of a new species of Borrelia. We propose the name Borrelia burgdorferi for this species. The type strain of B. burgdorferi is strain B31 (= ATCC 35210). In two separate studies the guanine-plus-cytosine content of the deoxyribonucleic acid of the type strain was determined to be 29.0 to 30.5 mol% (thermal denaturation method).

/pdf/borrelia-burgdorferi-sp-nov-etiologic-agent-of-lyme-disease-5c46o0jraj.pdf

Borrelia burgdorferi sp. nov.: Etiologic Agent of Lyme Disease

The minimal growth temperature of the pathogenic leptospires is between 13 and 15 C. The saprophytic leptospires have a minimal growth temperature between 5 and 10 C, or approximately 5 C below that of the pathogens. The capability of the saprophytic leptospires to grow at temperatures below those which allow the growth of the pathogenic leptospires provides a simple method of discrimination. With an inoculum yielding approximately 8 × 107 cells per ml in the test medium and an incubation temperature of 13 C, the saprophytic leptospires were easily differentiated from the pathogenic leptospires. All 13 saprophytic leptospires tested grew in the 10% rabbit serum medium at 13 C, whereas none of the 20 pathogens grew during the 30-day incubation period.

Differentiation of Pathogenic and Saprophytic Leptospires I. Growth at Low Temperatures

Serum specimens from 163 persons with Lyme disease, tick-borne or louse-borne relapsing fever, yaws, syphilis, leptospirosis, or Rocky Mountain spotted fever were analyzed to assess the specificity of indirect fluorescent antibody (IFA) tests, an enzyme-linked immunosorbent assay (ELISA), and microscopic agglutination (MA) procedures. Strong cross-reactivity occurred when sera from individuals with Lyme disease, tick-borne relapsing fever, and louse-borne relapsing fever were tested against heterologous Borrelia antigens. Antibodies to Borrelia burgdorferi bound to Treponema pallidum in immunofluorescence tests for syphilis. Sera from subjects with syphilis cross-reacted in IFA tests and the ELISA for Lyme disease. Immunoglobulin antibodies to Borrelia or Treponema spirochetes, however, did not react with serovars of Leptospira interrogans in MA or IFA tests, and the prevalence of false-positive results in the reciprocal analyses was negligible.

Cross-Reactivity in Serological Tests for Lyme Disease and Other Spirochetal Infections

We monitored the antibody responses of 55 treated patients with early Lyme disease and physician-documented erythema migrans. Six sequential serum samples were obtained from patients before, during, and until one year after antibiotic therapy and analyzed by in-house enzyme-linked immunosorbent (ELISA) and immunoblot assays. An immunoblot procedure utilizing a gradient gel and an image analysis system was developed. A relational database management system was used to analyze the results and provide criteria for early disease immunoblot interpretation. Recommended criteria for the immunoglobulin M (IgM) immunoblot are the recognition of two of three proteins (24, 39, and 41 kDa). The recommended criteria for a positive IgG immunoblot are the recognition of two of five proteins (20, 24 [> 19 intensity units], 35, 39, and 88 kDa). Alternatively, if band intensity cannot be measured, the 22-kDa protein can be substituted for the 24-kDa protein with only a small decrease in sensitivity. Monoclonal antibodies were used to identify all these proteins except the 35-kDa protein. With the proposed immunoblot interpretations, the sequential serum samples were examined. At visit 1, the day of diagnosis and initiation of treatment, 54.5% of the serum samples were either IgM or IgG positive. The peak antibody response, with 80% of the serum samples positive, occurred at visit 2, 8 to 12 days into treatment. The sensitivities of the IgM and IgG immunoblot for detecting patients that were seropositive into the study period were 58.5 and 54.6%, respectively, at visit 1 and 100% at visit 2. Twenty percent of the patients remained seronegative throughout the study. The specificities of the IgM and IgG immunoblots were 92 to 94% and 93 to 96%, respectively. The IgM immunoblot and ELISA were similar in sensitivities, whereas the IgG immunoblot had greater sensitivity than the IgG ELISA (P = 0.006).

Immunoblot interpretation criteria for serodiagnosis of early Lyme disease.

Borrelia burgdorferi, the causative agent of Lyme disease, was isolated from the liver of a passerine bird, Catharus fuscescens (veery), and from larval Ixodes dammini (tick) feeding on Pheucticus ludovicianus (rose-breasted grosbeak) and Geothlypis trichas (common yellowthroat). In indirect immunofluorescence antibody tests, isolates reacted with polyclonal and monoclonal (H5332) antibodies. Studies on the DNA composition of the veery liver isolate and the strain cultured from an I. dammini larva indicated that both were B. burgdorferi and not Borrelia anserina or Borrelia hermsii. The veery liver isolate infected hamsters and a chick. In contrast, B. anserina infected chicks but not hamsters. B. burgdorferi is unique among Borrelia spp. in being infectious to both mammals and birds. We suggest that the cosmopolitan distribution of B. burgdorferi may be caused by long-distance dispersal of infected birds that serve as hosts for ticks.

Russell C. Johnson

Papers

Borrelia burgdorferi sp. nov.: Etiologic Agent of Lyme Disease

Differentiation of Pathogenic and Saprophytic Leptospires I. Growth at Low Temperatures

Cross-Reactivity in Serological Tests for Lyme Disease and Other Spirochetal Infections

Immunoblot interpretation criteria for serodiagnosis of early Lyme disease.

Involvement of birds in the epidemiology of the Lyme disease agent Borrelia burgdorferi.