SEARCH · PubMed Health

Results for “LEPTOSPIRA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed2006

Determining risk for severe leptospirosis by molecular analysis of environmental surface waters for pathogenic Leptospira.

BACKGROUND: Although previous data indicate that the overall incidence of human leptospirosis in the Peruvian Amazon is similar in urban and rural sites, severe leptospirosis has been observed only in the urban context. As a potential explanation for this epidemiological observation, we tested the hypothesis that concentrations of more virulent Leptospira would be higher in urban than in rural environmental surface waters. METHODS AND FINDINGS: A quantitative real-time PCR assay was used to compare levels of Leptospira in urban and rural environmental surface waters in sites in the Peruvian Amazon region of Iquitos. Molecular taxonomic analysis of a 1,200-bp segment of the leptospiral 16S ribosomal RNA gene was used to identify Leptospira to the species level. Pathogenic Leptospira species were found only in urban slum water sources (Fisher's exact test; p = 0.013). The concentration of pathogen-related Leptospira was higher in urban than rural water sources (approximately 10(3) leptospires/ml versus 0.5 x 10(2) leptospires/ml; F = 8.406, p < 0.05). Identical 16S rRNA gene sequences from Leptospira interrogans serovar Icterohaemorrhagiae were found in urban slum market area gutter water and in human isolates, suggesting a specific mode of transmission from rats to humans. In a prospective, population-based study of patients presenting with acute febrile illness, isolation of L. interrogans-related leptospires from humans was significantly associated with urban acquisition (75% of urban isolates); human isolates of other leptospiral species were associated with rural acquisition (78% of rural isolates) (chi-square analysis; p < 0.01). This distribution of human leptospiral isolates mirrored the distribution of leptospiral 16S ribosomal gene sequences in urban and rural water sources. CONCLUSIONS: Our findings data support the hypothesis that urban severe leptospirosis in the Peruvian Amazon is associated with higher concentrations of more pathogenic leptospires at sites of exposure and transmission. This combined quantitative and molecular taxonomical risk assessment of environmental surface waters is globally applicable for assessing risk for leptospiral infection and severe disease in leptospirosis-endemic regions.

Environment↗

PubMed2003

Leptospira interrogans activation of human peripheral blood mononuclear cells: preferential expansion of TCR gamma delta+ T cells vs TCR alpha beta+ T cells.

Innate and adaptive immune responses induced by leptospirosis have not been well characterized. In this study we show that in vitro exposure of naive human PBMC to Leptospira interrogans results in cell proliferation and the production of IFN-gamma, IL-12, and TNF-alpha. Cell proliferation was highest when using high numbers of Leptospira. Optimal cell proliferation occurred at 6-8 days, and the majority of cells contained in these cultures were gamma/delta T cells. These cultures showed a 10- to 50-fold expansion of gamma/delta T cells compared with the initial cellular input. Additionally, these cultures contained elevated numbers of NK cells. In contrast, exposure of PBMC to low numbers of Leptospira failed to induce gammadelta T cell or NK cell expansion, but induced significant alphabeta T cell expansion. Vgamma9/Vdelta2 were expressed on all gamma/delta T cells expanded by exposure of PBMC to Leptorspira: Leptospira stimulation of purified TCRgammadelta(+) T cells, obtained from 8-day cultures of Leptospira-stimulated PBMC, induced high levels of IFN-gamma production, but no cell proliferation, suggesting that such stimulation of gammadelta T cells did not depend on specialized accessory cells or Ag processing. Finally, in patients with acute leptospirosis, there was a significant (4- to 5-fold) increase in the number of peripheral blood TCRgammadelta(+) T cells. These results indicate that Leptospira can activate gammadelta T cells and alphabeta T cells and will guide further investigations into the roles of these T cell populations in host defense and/or the pathology of leptospirosis.

Antigen Presentation↗

PubMed2006

Duplex PCR-hybridization based detection of pathogenic Leptospira in environmental water samples obtained from endemic areas in northeast region of Thailand.

Leptospirosis, a major health problem worldwide, is known to be endemic in the northeastern part of Thailand with the risk of infection by exposure to pathogenic Leptospira in contaminated aquatic environment. A method based on PCR-hybridization detection of pathogenic Leptospira in water was established. The method included filtration of water sample through membrane filters of two pore sizes, DNA extraction from filters using a guanidine thiocyanate extraction method, a duplex-PCR assay with two primer pairs, and hybridization with a synthetic LipL32 DNA probe. The duplex-PCR allowed detection of two products of 279 bp for LipL32 gene and 430 bp for 16S rRNA gene. In water samples artificially seeded with serovar bratislava, at least 10(3) cells could be analyzed by PCR-agarose gel electrophoresis and 1-10 cells by PCR-Southern blot hybridization. The protocol was applied to the detection of pathogenic Leptospira in environmental waters collected from endemic areas in the northeast region of Thailand. Of 100 water samples analyzed, 23 samples were positive for pathogenic Leptospira with PCR performed with Southern blot hybridization only, but none was detected by PCR-agarose gel-electrophoresis. However, PCR performed with the chemiluminescent LipL32 probe using the Fluorescein ULS labeling facilitated the detection of low numbers of pathogenic Leptospira in water. This method should prove useful for monitoring of pathogenic Leptospira pollution in environmental waters, and has the potential to become a valuable tool to the surveillance of leptospirosis in endemic areas, thus leading to enhanced public health protection.

Animals↗

PubMed1990

[Detection of the microquantity DNA of Leptospira interrogans by polymerase chain reaction].

Leptospirosis is a severe zoonosis in the world. The methods for detecting leptospira are not sensitive and specific so far. The problems in early diagnosis and epidemiological identification of Leptospirosis remain unsolved. Two recombinant DNA fragments of serogroup Icterohaemorrhagiae, Leptospira were selected by repeated molecular cloning and screening in this study firstly. One of them can hybridize with the DNA of various serogroups of Leptospira interrogans; the other can only hybridize with the DNA of serogroup Icterohaemorrhagiae. After the nucleotides sequence analysis, from these 2 recombinant DNA fragments, 2 pairs of polymerase chain reaction (PCR) oligonucleotide primers were synthesized, named primer B 1, 2 and primer B 3, 4 PCRs were carried out with these 2 primers for detecting the microquantity (0.1 ng) of various serovars, serogroup of leptospires. All the DNA of Leptospira interrogans can be amplified by primer B 1, 2, and only the DNA of serogroup icterohaemorrhagiae, Leptospira reacted specially with primer B 3, 4. The DNA of non-pathogenetic Leptospira and some other microbes, however, had no amplification at all. This study is first reported at home and abroad. The results demonstrate that PCR is a very sensitive and specific technique of DNA amplification, which can be used as a powerful tool in the early diagnosis and epidemiological identification of leptospirosis.

Animals↗

PubMed1979

[Susceptibility and sensitivity of the Siberian lemming and Middendorff's vole to leptospirae of the grippotyphosa serogroup].

Siberian lemmings and Middendorf's voles were found to be susceptible to infection caused by Leptospira of the Grippotyphosa serogroup after the intraperitoneal injection of Leptospira culture, the application of the culture or infected urine to the skin, as well as after Leptospira-carrying animals were placed together with the animals to be infected. The infectious sensitivity of these animals to Leptospira was not high: leptospiruria was observed for 1-3 weeks; in some of the voles leptospiruria was slightly pronounced, whereas other voles had a great number of Leptospira in urine. Antibodies appeared in the blood on day 5 after infection, and their titers increased till days 61-63. In no case could Leptospira be isolated from the kidneys of the animals killed on days 61-83 of the experiment.

Animals↗

PubMed1995

Studies on the incidence of leptospirosis and possible transmission of Leptospira during leptospiraemia.

During the year 1991 and in the first half year of 1992 a total of 179 cases and 288 cases respectively were tested for the presence of Leptospira by dark ground microscopy and 86 cases (48%) and 157 cases (54.5%) were found to be positive for Leptospira in their blood samples only. The disease was endemic and more prevalent in the age group of 5 to 14 years and 15 to 54 years and affected both sexes. Clinical categorisation of 169 cases in 1991 and 266 cases in the first half of the year 1992 along with the dark ground microscopy results showed that there was no strict correlation between the concentration of Leptospira in the blood and the severity of infection. Epidemiological data regarding the occupation and the contacts indicated that students and medical staff accounted for more than fifty percent of leptospiral infection and there was the possibility of transmission of Leptospira during leptospiraemia. Dark ground microscopy studies on blood samples from 20 cases who came for repeat testing showed the presence of Leptospira in blood up to 43 days and suggested that the convalescent carrier may have a role in the transmission of Leptospira during Leptospiraemia.

Adolescent↗

PubMed2000

The maintenance of challenge strains used in the potency test for canine leptospira vaccines.

The challenge test for leptospira vaccines required by most licensing authorities is difficult to standardise and unreliable. One of the main contributory factors to this, is the difficulty in maintaining the virulence of the challenge strain. This paper describes work carried out to assess the practicality of storing challenge strains of Leptospira canicola and Leptospira icterohaemorrhagiae in liquid nitrogen. The effects of different concentrations of glycerol and dimethyl sulphoxide on the recovery of virulent and avirulent strains of Leptospira canicola and Leptospira icterohaemorrhagiae were investigated. Concentrations of cryopreservant above 5% increased the time taken for the leptospires to grow after recovery from vials stored in liquid nitrogen. In addition, the virulence of five challenge strains were shown to be little affected after 18 passages in vitro.

Animals↗

PubMed2003

Leptospira spp. possess a complete haem biosynthetic pathway and are able to use exogenous haem sources.

Unlike the spirochetes Borrelia burgdorferi and Treponema pallidum, Leptospira spp. contain genes encoding the enzymes for most biosynthetic pathways. In this study, we describe the first haem biosynthetic pathway genes in the order Spirochaetales. Sequence analysis of the L. interrogans genome shows that all haem biosynthetic genes (hemA, heml, hemB, hemC, hemE, hemN, hemY and hemH) are clustered in a 15 kb region of the CII secondary chromosome. Although no hemD homologue (encoding uroporphyrinogen III synthase) was found in the genome, the L. interrogans hemC gene (encoding porphobilinogen deaminase) was able to restore uroporphyrinogen III synthase activity in an Escherichia coli Delta hemD mutant, suggesting that the L. interrogans hemC gene encodes a bifunctional enzyme. Similarly, we show that the L. interrogans hemH gene (encoding ferrochelatase, the terminal enzyme of the haem biosynthetic pathway) is able to complement a ferrochelatase-defective E. coli Delta hemH mutant. Further investigation of ferrochelatases was undertaken in both saprophytic and pathogenic species of Leptospira. Ferrochelatase activity of 2.3 +/- 0.1 nmol h-1 mg-1 (in comparison with 0.25 +/- 0.02 nmol h-1 mg-1 in E. coli) was found in membrane fractions of pathogenic and saprophytic species, suggesting that ferrochelatase is a membrane-associated protein. Leptospira biflexa allelic exchange mutants containing an inactivated hemH gene were recovered only when exogenous haemin was present. The results indicate that haem is an essential growth factor for Leptospira, and that these spirochetes are capable of both de novo synthesis or uptake of haem. This may have implications in a better understanding of the pathogenesis of Leptospira.

Amino Acid Sequence↗

PubMed1983

Aminopeptidase activity of Leptospira strains.

A total of 15 cultures of Leptospira were examined for aminopeptidase activity using 22 aminoacyl-beta-naphthylamde substrates. Activity was demonstrated in each of the cultures. Extracts from serovars of Leptospira interrogans preferentially hydrolysed the same range of substrates. The level of hydrolysis of the preferred substrates for the seven strains of L. interrogans was distinctively higher than that demonstrated for the six Leptospira biflexa strains. Extracts from cultures of Leptospira illini and Leptospira parva sp. nov. exhibited profiles different to those demonstrated for the other 13 leptospiral cultures examined.

Aminopeptidases↗

PubMed1964

5-FLUOROURACIL AS A SELECTIVE AGENT FOR GROWTH OF LEPTOSPIRAE.

Johnson, Russell C. (University of Minnesota, Minneapolis), and Palmer Rogers. 5-Fluorouracil as a selective agent for growth of leptospirae. J. Bacteriol. 87:422-426. 1964.-The use of 5-fluorouracil (FU) as a selective agent for the growth of leptospirae was investigated. Both the growth rate and the final cell yield of Leptospira pomona were unaltered with FU added to the medium at concentrations varying from 50 to 1,000 mug/ml. Growth of this organism was initiated with as few as five organisms per ml in the FU medium. With C(14)-FU, it was demonstrated that FU was not incorporated into L. pomona nucleic acids. Other leptospirae tested grew normally in the presence of FU. By use of the FU medium, L. canicola was successfully isolated from contaminated urine of experimentally infected dogs. Also, contaminated cultures of leptospirae were purified by passage through the FU medium.

Animals↗

PubMed2000

Antibody isotypes in sera of equine fetuses aborted due to Leptospira interrogans serovar pomona-type kennewicki infection.

Leptospira-specific antibody isotypes in sera of late term equine fetuses aborted due to Leptospira interrogans serovar pomona-type kennewicki infection were characterized and compared with those of their dams. IgM was the dominant Leptospira-Specific isotype in both fetuses and mares. However, IgGa was the isotype in highest concentration in petal sera and strong Leptospira-specific IgGa but no IgGb and little or no IgG(T) were detected. In contrast, although IgGb was quantitatively the dominant isotype in mares serum, Leptospira-specific serum IgG in aborting mares was dominated by IgG(T) but also included large amounts of IgGa and IgGb. IgGa and IgGb were quantitatively the dominant isotypes in sera of fetuses and mares, respectively. Affinity purified IgGa from fetuses did not agglutinate leptospires but serum devoid of IgGa did, suggesting that IgM is the principal agglutinating antibody. It is concluded that the equine fetus is deficient in IgGb and IgG(T) synthesis.

Abortion, Veterinary↗

PubMed2004

Proposal to list ATCC 43642 as the type strain of Leptospira interrogans in the Approved Lists of Bacterial Names. Request for an opinion.

ATCC 23581(T) has been cited as the type strain of Leptospira interrogans since 1980. In 1986, the Centers for Disease Control informed the ATCC that this strain was Leptospira interrogans serovar budapest, not serovar icterohaemorrhagiae as deposited originally. An authentic culture of the Leptospira interrogans serovar icterohaemorrhagiae RGA(T) strain was then submitted and assigned ATCC 43642, which was designated as the type strain of Leptospira interrogans in an article by Yasuda et al. [Yasuda et al. (1987). Int J Syst Bacteriol 37, 407-415]. In this Request for an Opinion to the Judicial Commission, it is proposed that a correction be made in the Approved Lists of Bacterial Names to acknowledge ATCC 43642 as the type strain of Leptospira interrogans.

Leptospira interrogans serovar icterohaemorrhagiae↗

PubMed2006

New Leptospira serovar Sokoine of serogroup Icterohaemorrhagiae from cattle in Tanzania.

The prevalence of leptospirosis is generally high in domestic animals and rodents in Tanzania. Identification of Leptospira isolates from cattle was carried out to establish prevalent Leptospira serovars. Serological typing was done based on monoclonal antibodies and the standard cross-agglutination absorption test. Molecular typing involved pathogenic- and saprophytic-specific PCRs and a PCR specifically amplifying DNA from the species Leptospira kirschneri. DNA fingerprinting with primers derived from sequences of insertion elements IS1500 and IS1533 was carried out. Both serological and molecular characterization indicated that one of the Leptospira isolates, coded RM1, represents a new serovar of the species L. kirschneri of serogroup Icterohaemorrhagiae. The serovar name Sokoine is proposed for this new Leptospira isolate.

Agglutination Tests↗

PubMed2002

Rapid translocation of polarized MDCK cell monolayers by Leptospira interrogans, an invasive but nonintracellular pathogen.

Pathogenic spirochetes of the genus Leptospira are a major cause of human zoonotic infectious disease worldwide. After gaining entry through the skin, the organism causes disease by hematogenously disseminating to multiple organs. The mechanism by which it penetrates the mammalian cell barriers to disseminate is not well understood. In this study, we used a low-passage-number isolate of Leptospira interrogans to elucidate the invasive potential of this spirochete. Quantification of bacteria by dark-field microscopy revealed that pathogenic spirochetes were able to translocate through polarized MDCK cell monolayers at a rate significantly greater than that of nonpathogenic Leptospira or a recognized invasive bacterial pathogen, Salmonella: In contrast to Salmonella, L. interrogans did not alter transepithelial electrical resistance during cell translocation. Both transmission and scanning electron microscopy revealed tight association of the extracellular spirochetes with the host cell plasma membrane, without membrane perturbations suggestive of cytoskeletal rearrangement. Spirochetes were not observed within intercellular junctions or membrane-bound compartments inside cells. They were found within the cytoplasm of only 8% of the counted cells. These results indicate that Leptospira is an invasive but not a facultative intracellular organism. We propose that the rapid translocation of mammalian cells by pathogenic Leptospira is a mechanism designed to evade killing by host cells that permits the organism to quickly reach the bloodstream and disseminate to multiple organs.

Animals↗

PubMed2005

LruA and LruB, novel lipoproteins of pathogenic Leptospira interrogans associated with equine recurrent uveitis.

Recurrent uveitis as a sequela to Leptospira infection is the most common infectious cause of blindness and impaired vision of horses worldwide. Leptospiral proteins expressed during prolonged survival in the eyes of horses with lesions of chronic uveitis were identified by screening a phage library of Leptospira interrogans DNA fragments with eye fluids from uveitic horses. Inserts of reactive phages encoded several known leptospiral proteins and two novel putative lipoproteins, LruA and LruB. LruA was intrinsically labeled during incubation of L. interrogans in medium containing [14C]palmitic acid, confirming that it is a lipoprotein. lruA and lruB were detected by Southern blotting in infectious Leptospira interrogans but not in nonpathogenic Leptospira biflexa. Fractionation data from cultured Leptospira indicate that LruA and LruB are localized in the inner membrane. Uveitic eye fluids contained significantly higher levels of immunoglobulin A (IgA) and IgG specific for each protein than did companion sera, indicating strong local antibody responses. Moreover, LruA- and LruB-specific antisera reacted with equine ocular components, suggesting an immunopathogenic role in leptospiral uveitis.

Acylation↗

PubMed2006

Toll-like receptor 4 protects against lethal Leptospira interrogans serovar icterohaemorrhagiae infection and contributes to in vivo control of leptospiral burden.

The roles of innate immune responses in protection from or pathogenesis of severe leptospirosis remain unclear. We examined the role of Toll-like receptors (TLRs) in mouse infection and macrophage responses to Leptospira. C3H/HeJ mice (TLR4 deficient) and C3H/HeJ-SCID mice, but not C3H/OuJ mice (TLR4 intact), died after intraperitoneal infection with Leptospira interrogans serovar Icterohaemorrhagiae. Death in both C3H/HeJ mouse strains was associated with jaundice and pulmonary hemorrhage, similar to the patient from whom the isolate was obtained. In chronic sublethal infection, TLR4-deficient mice harbored more leptospires in liver, lung, and kidney than control mice. Heat-killed Leptospira stimulated macrophages to secrete proinflammatory cytokines, tumor necrosis factor alpha, interleukin-6, and macrophage inflammatory protein 2 not inhibited by polymyxin B, suggesting that leptospiral lipopolysaccharide (LPS) did not drive these responses. Anti-TLR4 and anti-MD-2 but not anti-CD14 monoclonal antibodies inhibited cytokine production. Peritoneal macrophages from CD14-/- and TLR2-/- mice exhibited no defect in cytokine responses to Leptospira compared to controls. Macrophages from C3H/HeJ, TLR4-/-, and MyD88-/- mice secreted far-lower levels of cytokines than wild-type macrophages in response to Leptospira. TLR4 plays a crucial role in protection from acute lethal infection and control of leptospiral burden during sublethal chronic infection. Cytokine responses in macrophages correlated with leptospiral clearance. These TLR4-dependent but CD14/TLR2-independent responses are likely mediated by a leptospiral ligand(s) other than LPS.

Adolescent↗

PubMed1997

Identification of pathogenic Leptospira genospecies by continuous monitoring of fluorogenic hybridization probes during rapid-cycle PCR.

Partial sequences of 23S rRNA gene PCR products from 23 strains of 6 pathogenic Leptospira genospecies and from 8 strains of the saprophytic Leptospira biflexa were determined. Sequence analyses enabled Leptospira genus-specific amplification primers and pathogen-specific fluorogenic adjacent hybridization probes to be designed and synthesized. A PCR protocol was developed in which changes in fluorescence emission resulting from specific annealing of fluorogenic adjacent hybridization probes to the target DNA were continuously monitored. Nine strains of the pathogenic Leptospira genospecies could be differentiated from Leptonema illini, Escherichia coli, and eight strains of Leptospira biflexa. The PCR method was rapid, requiring 18 min for the completion of 45 cycles. It was also simple and flexible, as DNA templates prepared by four different methods, including the simple boiling method, could be used without adverse effects. Two hundred copies of target, equivalent to 100 cells, could be detected.

Animals↗

PubMed2000

Detection of Leptospira spp. in the aqueous humor of horses with naturally acquired recurrent uveitis.

Leptospiral organisms have long been presumed to be associated with the presence of equine recurrent uveitis. This project was undertaken to determine the presence of Leptospira spp. in the aqueous humor of horses with uveitis to determine if there was an association with inflammation. Thirty horses were determined to have recurrent uveitis based on clinical evaluation or history. Sixteen horses were judged clinically and historically to be free of uveitis and were used as controls. Aqueous humor samples were cultured and evaluated by PCR for the presence of Leptospira DNA. Serum was collected and evaluated for the presence of antibodies against five serovars in a leptospirosis panel. Twenty-one of 30 horses with recurrent uveitis and one of 16 uveitis-free horses were positive by PCR for the presence of Leptospira DNA. Six of these 21 horses with uveitis were culture positive for leptospires from the aqueous humor. Serologic results did not correlate well with the presence of Leptospira DNA or organisms in the aqueous humor. Leptospira spp. are present in a high percentage of horses with naturally occurring recurrent uveitis.

Animals↗