Rickettsia
Scientific classification
Kingdom: Bacteria Phylum: Proteobacteria Class: Alpha Proteobacteria Order: Rickettsiales Family: Rickettsiaceae Genus: Rickettsia da Rocha-Lima, 1916
Species
Rickettsia felis Rickettsia prowazekii Rickettsia rickettsii Rickettsia typhi Rickettsia conorii Rickettsia africae etc. Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Orders Alpha Proteobacteria    Caulobacterales - e. ... Families Rickettsiaceae Ehrlichiaceae Holosporaceae The Rickettsiales are an order of small proteobacteria. ... Genera Rickettsia Orientia Wolbachia The Rickettsiaceae are a family of bacteria, including most notably the genus Rickettsia. ... Binomial name Rickettsia prowazekii Epidemic typhus is a form of typhus caused by the bacillus Rickettsia prowazekii, carried by the human body louse Pediculus humanus. ... Binomial name Rickettsia rickettsii Rocky Mountain spotted fever is the most severe and most frequently reported rickettsial illness in the United States, and has been diagnosed throughout the Americas. ...

Rickettsia is a genus of non-motile, Gram-negative, non-sporeforming, highly pleomorphic bacteria that can present as cocci (0.1 μm in diameter), rods (1-4 μm long) or thread-like (10 μm long). Obligate intracellular parasites, the Rickettsia depend on entry, growth, and replication within the cytoplasm of eukaryotic host cells (typically endothelial cells).^[1] Because of this, Rickettsia cannot live in artificial nutrient environments and are grown either in tissue or embryo cultures (typically, chicken embryos are used). In the past they were regarded as microorganisms positioned somewhere between viruses and true bacteria. The majority of Rickettsia bacteria are susceptible to antibiotics of the tetracycline group. For other uses of the word, please see Genus (disambiguation). ... Motility is a biological term which refers to the ability to move spontaneously and independently. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family. ... This page is a candidate to be copied to Wiktionary. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... coccus (plural - cocci) are any spherical or near spherical bacteria. ... Organelles. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... It has been suggested that embryology be merged into this article or section. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Staphylococcus aureus - Antibiotics test plate. ... Tetracycline (INN) (IPA: ) is a broad-spectrum antibiotic produced by the streptomyces bacterium, indicated for use against many bacterial infections. ...

Rickettsia species are carried as parasites by many ticks, fleas, and lice, and cause diseases such as typhus, rickettsialpox, Brill-Zinsser disease, Boutonneuse fever, Rocky Mountain spotted fever, and endemic typhus in human beings. They have also been associated with a range of plant diseases. Like viruses, they grow only in living cells. The name rickettsia is often used for any member of the Rickettsiales. They are thought to be the closest living relatives to bacteria that were the origin of the mitochondria organelle that exist in most eukaryotic cells. A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Families Ixodidae - Hard ticks Argasidae - Soft ticks Nuttalliellidae Wikispecies has information related to: Ixodoidea Tick is the common name for the small arachnids that, along with other mites, constitute the order Acarina. ... Families Tungidae â€“ sticktight and chigoe fleas (chiggers) Pulicidae â€“ common fleas Coptopsyllidae Vermipsyllidae â€“ carnivore fleas Rhopalopsyllidae â€“ marsupial fleas Hypsophthalmidae Stephanocircidae Pygiopsyllidae Hystrichopsyllidae â€“ rat and mouse fleas Leptopsyllidae â€“ mouse and rat fleas Ischnopsyllidae â€“ bat fleas Ceratophyllidae:-fleas mainly associated with rodents Amphipsyllidae Malacopsyllidae Dolichopsyllidae â€“ rodent fleas Ctenopsyllidae Flea is the common name... Suborders Anoplura (sucking lice) Rhyncophthirina Ischnocera (avian lice) Amblycera (chewing lice) Lice (singular: louse) (order Phthiraptera) are an order of over 3000 species of wingless parasitic insects. ... The term disease refers to an abnormal condition of an organism that impairs function. ... It has been suggested that this article or section be merged with Epidemic typhus. ... Rickettsialpox is caused by bacteria found in the Rickettsia family (Rickettsia akari) but humans contract the disease through a much less direct route. ... Binomial name Rickettsia prowazekii Epidemic typhus is a form of typhus caused by the bacillus Rickettsia prowazekii, carried by the human body louse Pediculus humanus. ... Boutonneuse fever (also called Mediterranean Fever) is a fever as a result of a Rickettsial infection. ... Binomial name Rickettsia rickettsii Wolbach, 1919 Wikispecies has information related to: Ixodidae Wikispecies has information related to: Rickettsia Rocky Mountain spotted fever is the most severe and most frequently reported rickettsial illness in the United States, and has been diagnosed throughout the Americas. ... Endemic typhus is caused by certain species of Rickettsia - namely , transmitted by fleas infesting rats, and less often , transmitted by fleas carried by cats or opossums. ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus (from the Latin noun virus, meaning toxin or poison) is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the... Families Rickettsiaceae Ehrlichiaceae Holosporaceae The Rickettsiales are an order of small proteobacteria. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ...

Human pathogenesis

The Rickettsia human pathogens are generally grouped as follows:

Spotted fever group

• R. rickettsii (Western hemisphere)

Rocky Mountain spotted fever

• R. akari (USA, former Soviet Union)

Rickettsialpox

• R. conorii (Mediterranean countries, Africa, Southwest Asia, India)

Boutonneuse fever

• R. sibirica (Siberia, Mongolia, northern China)

Siberian tick typhus

• R. australis (Australia)

Australian tick typhus

• R. japonica (Japan)

Oriental spotted fever

Binomial name Rickettsia rickettsii Wolbach, 1919 Wikispecies has information related to: Ixodidae Wikispecies has information related to: Rickettsia Rocky Mountain spotted fever is the most severe and most frequently reported rickettsial illness in the United States, and has been diagnosed throughout the Americas. ... Rickettsialpox is caused by bacteria found in the Rickettsia family (Rickettsia akari) but humans contract the disease through a much less direct route. ... Boutonneuse fever (also called Mediterranean Fever) is a fever as a result of a Rickettsial infection. ...

Typhus group

• R. prowazekii (Worldwide)

Epidemic, recrudescent and sporadic typhus

• R. typhi (Worldwide)

Murine (endemic) typhus

Binomial name Rickettsia prowazekii Epidemic typhus is a form of typhus caused by the bacillus Rickettsia prowazekii, carried by the human body louse Pediculus humanus. ... It has been suggested that this article or section be merged with Epidemic typhus. ...

Scrub typhus group

• The causative agent of scrub typhus formerly known as R. tsutsugamushi has been reclassified into the genus Orientia.

Scrub typhus is a form of typhus caused by Orientia tsutsugamushi and transmitted by chiggers, which are found in areas of heavy scrub vegetation. ... Orientia is a genus of bacteria in family Rickettsiaceae. ...

Plant pathogenesis

The following plant diseases have been assocaited with Rickettsia-like organisms^[2].

• Beet latent Rosette RLO
• Citrus Greening bacterium
• Clover leaf RLO
• Grapevine infectious necrosis RLO
• Grapevine Pierce's RLO
• Grapevine yellos RLO
• Larch witche's broom disease
• Peach phoney RLO

Genomics

Certain segments of Rickettsial genomes resemble that of mitochondria.^[3] The deciphered genome of R. prowazekii is 1,111,523 bp long and contains 834 protein-coding genes.^[4] Unlike free-living bacteria, it contains no genes for anaerobic glycolysis or genes involved in the biosynthesis and regulation of amino acids and nucleosides. In this regard it is similar to mitochondrial genomes; in both cases, nuclear (host) resources are used. ATP production in Rickettsia is the same as that in mitochondria. In fact, of all the microbes known, the Rickettsia is probably the closest "relative" (in phylogenetic sense) to the mitochondria. Unlike the latter, the genome of R. prowazekii, however, contains a complete set of genes encoding for the tricarboxylic acid cycle and the respiratory-chain complex. Still, the genomes of the Rickettsia as well as the mitochondria are frequently said to be "small, highly derived products of several types of reductive evolution". In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Base pairs, of a DNA molecule. ... Phenylalanine is one of the standard amino acids. ... Nucleosides are glycosylamines made by attaching a nucleobase (often reffered to simply as bases) to a ribose ring. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...

The recent discovery of another parallel between Rickettsia and viruses may become a basis for fighting HIV infection.^[5] Human immune response to the scrub typhus pathogen, Orientia tsutsugamushi rickettsia, appears to provide a beneficial effect against HIV infection progress, negatively influencing the virus replication process. A probable reason for this actively studied phenomenon is a certain degree of homology between the rickettsia and the virus - namely, common epitope(s) due to common genome fragment(s) in both pathogens. Surprisingly, the other infection reported to be likely to provide the same effect (decrease in viral load) is the virus-caused illness dengue fever. Species Human immunodeficiency virus 1 Human immunodeficiency virus 2 Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). ... Scrub typhus is a form of typhus caused by Orientia tsutsugamushi and transmitted by chiggers, which are found in areas of heavy scrub vegetation. ... In biology, homology is any similarity between structures that is due to their shared ancestry. ... An epitope is the part of a macromolecule that is recognized by the immune system, specifically by antibodies, B cells, or cytotoxic T cells. ... Dengue fever (IPA: ) and dengue hemorrhagic fever (DHF) are acute febrile diseases, found in the tropics, with a geographical spread similar to malaria. ...

Naming

The genus Rickettsia is named after Howard Taylor Ricketts (1871–1910), who worked on and eventually died of typhus. Despite the similar name, Rickettsia bacteria do not cause rickets. The disease of rickets takes its name from the Greek word for spine, hrake, and is a vitamin deficiency disease, not an infectious disease. Howard Taylor Ricketts (1871-1910) was an American pathologist after whom the Rickettsiaceae family and the Rickettsiales are named. ... 1871 (MDCCCLXXI) was a common year starting on Sunday (see link for calendar). ... 1910 (MCMX) was a common year starting on Saturday (link will display calendar) of the Gregorian calendar or a common year starting on Sunday of the 13-day slower Julian calendar. ... Rickets is a softening of the bones in children potentially leading to fractures and deformity. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... Avitaminosis is any disease caused by chronic or long-term vitamin deficiency or caused by a defect in metabolic conversion, such as tryptophan to niacin. ...

References

1. ^ Walker DH (1996). Rickettsiae. In: Barron's Medical Microbiology (Barron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1. 
2. ^ Smith IM, Dunez J, Lelliot RA, Phillips DH, Archer SA (1988). European Handbook of Plant Diseases.. Blackwell Scientific Publications. ISBN 0-632-01222-6. 
3. ^ Emelyanov VV (2003). "Mitochondrial connection to the origin of the eukaryotic cell". Eur J Biochem 270 (8): 1599-618. PubMed. 
4. ^ Andersson SG, et al (1998). "The genome sequence of Rickettsia prowazekii and the origin of mitochondria". Nature 396 (6707): 133-40. PubMed. 
5. ^ Kannangara S, DeSimone JA, Pomerantz RJ (2005). "Attenuation of HIV-1 infection by other microbial agents". J Infect Dis 192 (6): 1003-9. PubMed.