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Leptospira
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Tanu Sagar, Nitin Gupta, Rama Chaudhry
The genus Leptospira, along with the genera Leptonema and Turneriella, makes up the family Leptospiraceae, within the order Spirochaetales, class Spirochaetes, phylum Spirochaetes [1]. The classification and nomenclature of Leptospira are complex based on phenotypic characters and genetic relatedness. In phenotypic classification, which is based on antigenic relatedness, Leptospira is separated into two species: L. interrogans, containing all pathogenic strains, and L. biflexa, containing saprophytic strains isolated from the environment [2]. Both of these species are divided into several serovars defined by agglutination after cross-absorption with homologous antigen. Serovars are considered distinct if more than 10% of the homologous titer remains in at least one of the two antisera on repeated testing. Over 60 serovars of L. biflexa sensu lato and more than 200 serovars of L. interrogans sensu lato have been recorded. Serovars that are antigenically related have traditionally been grouped into serogroups [3].
Prognosis and Impact of Recurrent Uveitis, the Ophthalmic Infection Caused by Leptospira spp.
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Charles Solomon Akino Mercy, Kalimuthusamy Natarajaseenivasan
Leptospires belong to the order Spirochaetales, family Leptospiraceae, genus Leptospira. These bacteria are long thin, about 0.1 µm in diameter by 6–20 µm in length. Electron microscopy shows a cylindrical cell body (i.e., protoplasmic cylinder) wound helically around an axistyle (0.01–0.02 µm in diameter), which comprises two axial filaments (a spirochetal form of a modified flagellum) inserted subterminally at the extremities of the cell body, with their free ends directed toward the middle of the cell (Bharti et al. 2003). They are helical bacteria with tight coils and have a typical double-membrane structure in which the cytoplasmic membrane and peptidoglycan cell wall are closely associated and are overlaid by an outer membrane that contains porins that allow solute exchange between the periplasmic space and the environment. Within the outer membrane, the leptospiral lipopolysaccharide (LPS) constitutes the main antigen and has a composition similar to that of other Gram-negative bacteria with lower endotoxic activity. It is characterized by active motility due to the presence of two periplasmic flagella with polar insertions in the periplasmic space and exhibits two distinct forms of movement, translational and non-translational. Either or both the ends of the single organism are blended or hooked. The free living (L. biflexa) and parasitic leptospires (L. interrogans) are morphologically indistinguishable, although the morphology of individual isolates varies with subculture in vitro and can be restored by passage in hamsters. Both saprophytic and pathogenic leptospires are present in nature. However, pathogenic leptospires mostly present in renal tubules of animals, whereas saprophytic leptospires were found to be present in many types of wet or humid environments.
Presence of Leptospira spp. and absence of Bartonella spp. in urban rodents of Buenos Aires province, Argentina
Published in Pathogens and Global Health, 2022
Leptospira spp. and Bartonella spp. are important zoonotic agents with worldwide distribution [17–20, 2,21–23]. Numerous studies worldwide reported the association of these bacteria and urban rodents [2,21,23–25]. Leptospirosis is caused by spirochetal bacteria from the genus Leptospira (family Leptospiraceae), with 64 species classified into two clades: pathogenic, or P clade, which includes isolates that cause human or animal infections, and saprophytic, or S clade, which includes species isolated from the environment that do not cause infections [26]. Species clustering in the pathogenic clade are considered more relevant due to their ability to cause a wide range of clinical signs, including multiple organ failure and even death [5,27–31]. Urban rodents are the main source of infection for humans and other vulnerable vertebrate hosts for leptospirosis. Humans may become infected with Leptospira spp. by direct contact with an infected animal or by indirect contact with soil or water contaminated with urine from an infected animal [18,30,31].
Identification of Leptospira spp. from environmental sources in areas with high human leptospirosis incidence in the Philippines
Published in Pathogens and Global Health, 2019
Marjo V. Mendoza, Windell L. Rivera
All sequences obtained in this study were submitted to the NCBI GenBank database. Genbank accession numbers of isolates are listed in Table 2. Identity of isolates was determined using the Basic Local Alignment Search Tool in the NCBI database (https://blast.ncbi.nlm.nih.gov/Blast.cgi). To construct phylogenetic trees, reference sequences from known Leptospira spp. and Turneriella parva (which belongs to the same Family Leptospiraceae) were extracted from GenBank. Sequences of other Philippine isolates from previous studies were also included in the analysis. Partial 16S rRNA gene sequences of L. yanagawae (AB758728.1) and L. licerasiae (AB758738.1), both from Region III, L. meyeri (AB758717.1) from NCR, and L. kmetyi gene sequences (AB937994.1 and AB937993.1) from Region VIII were used. These isolates were also obtained from soil and water samples [20,25]. Sequences were aligned and trimmed using the ClustalW algorithm in Bioedit v 7.2.5 [26]. The optimal DNA substitution model was identified based on Bayesian Information Criterion (BIC) in jModeltest v 2.1.10 software [27]. Oversaturation in sequences was also measured using the Xia test implemented in DAMBE v 5.2.5. Phylogenetic trees were reconstructed using Maximum Likelihood (ML), Neighbor-Joining (NJ), and Bayesian Inference (BI) methods. ML was done with 1,000 bootstrap replicates in Phyml 3.1 program [28], NJ was done in PAUP* v 4.0b10 program, and BI was done with 10,000,000 generations in MrBayes v 3.1.2 program [29]. Tree constructions were based on the parameters of the optimal DNA substitution model identified, TrN+G, with unequal substitution rate and 0.1780 gamma distribution factor. NJ and ML trees were drawn in TreeExplorer v 2.12 software program [30]. BI tree was drawn in Treeview v 1.6.6 [31].