Candidatus Neoehrlichia mikurensis
| " Candidatus Neoehrlichia mikurensis" | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| " Candidatus Neoehrlichia mikurensis" | ||||||||||||
| Kawahara et al. 2004 |
" Candidatus Neoehrlichia mikurensis" is a pathogenic ("disease-causing") bacterium . An infection can lead to Neoehrlichiose lead. It belongs to the family of the Anaplasmataceae in the order of the Rickettsiales , to which the Rickettsia are also counted. " Candidatus Neoehrlichia mikurensis" was found in rats and ticks , among others . The obligate intracellular living bacterium cannot yet be cultivated. According to the rules for the nomenclature of bacteria, it is therefore not assigned to a species , but described as a Candidatus .
features
These are gram-negative cells that appear cocci-shaped to changing shapes . Their size is 0.5 to 1.2 μm in diameter. They live intracellularly , in rats membrane-bound in the cytoplasm of endothelial cells . With the help of transmission electron microscopy , the cells in animal spleen tissue can be observed. In addition to the cell membrane , the bacterium also has another, outer membrane that appears wavy. Because of the intracellular way of life, the bacteria cannot be cultivated on the nutrient media that are commonly used .
Occurrence
" Candidatus Neoehrlichia mikurensis" was first detected in brown rats ( Rattus norvegicus ) from the Japanese island of Mikura . Also in ticks of the species Ixodes ovatus the bacterium in Japan was found. In addition to various types of ticks as vectors , the bacterium can also be found in reservoir hosts. In addition to the brown rat, other rodents are considered hosts as they commonly serve as hosts to the common wood tick ( Ixodes ricinus ) and related species.
An investigation carried out in Budapest ( Hungary ) between 2009 and 2011 on hedgehogs living in the city showed the occurrence of “ approx. Neoehrlichia mikurensis ". The hedgehogs are the species Erinaceus roumanicus , the northern white-breasted hedgehog . This means that animal species other than rodents can also be viewed as a possible reservoir for the bacterium.
Studies by the Institute for Medical Microbiology at the University of Zurich have shown that “ Approx. Neoehrlichia mikurensis “was detected in 5 to 10% of ticks in the greater Zurich area in 2012 . Based on the diseases of people as a result of infections with “ Approx. Neoehrlichia mikurensis “the geographical occurrence in Switzerland , Sweden , Germany , the Czech Republic and the People's Republic of China has been proven.
Systematics
The scientists who “ Approx. Neoehrlichia mikurensis ”, based on phylogenetic studies , propose a classification in the Anaplasmataceae family . The family is currently (as of 2014) assigned to five genera : Aegyptianella , Anaplasma , Ehrlichia , Neorickettsia and Wolbachia . As the generic name Neorickettsia was assigned based on the already existing generic name Rickettsia , Neoehrlichia is supposed to show the relationship to Ehrlichia .
Since the representatives of these genera all live intracellularly and therefore cannot be cultivated on common nutrient media, the ultrastructure (e.g. with the help of electron microscopy ) and the sequencing of genes are used for identification and classification . To do this, u. a. determines the nucleotides of 16S rRNA, a typical representative of ribosomal RNA for prokaryotes . Based on these results, a phylogenetic tree was created based on the neighbor joining method . The bacterial strain designated as TK4456 in the course of the study and two similar strains isolated from a brown rat in the People's Republic of China and from the common wood tick ( Ixodes ricinus ) in the Netherlands show their own clade . Representatives of the genus Ehrlichia are the closest relatives.
The obligate intracellular living pathogen cannot be cultivated so far and therefore cannot be described as a valid species according to the bacteriological code , but only as a Candidatus .
Medical importance
In 2010, scientists from the Institute for Medical Microbiology at the University of Zurich diagnosed a person with " Candidatus Neoehrlichia mikurensis" for the first time. Based on the infectious disease ehrlichiosis , which is caused by related bacteria of the genus Ehrlichia , they called the disease neoehrlichiosis. Related bacteria of the genus Anaplasma cause human granulocytic anaplasmosis .
The symptoms of neoehrlichiosis are unspecific: malaise, muscle and joint pain , high fever of up to 40 ° C (similar to relapsing fever ) and weight loss. Other symptoms described in the literature include: a. Headache , cough , nausea and vomiting . The duration of the fever is given as up to eight months. Laboratory diagnostics show anemia ( anemia ).
According to a medical study, the pathogen can cause inflammation in people with haematological or autoimmune diseases , which could be mistaken for symptoms of the original disease or atherosclerosis .
" Candidatus Neoehrlichia mikurensis" was detected in 5 to 10% of ticks in the greater Zurich area in 2012 . However, it has not yet been clarified whether or in how many cases the bacterium is transmitted in a tick bite and leads to an infection. Diseases resulting from infections with “ Approx. Neoehrlichia mikurensis ”could be detected in people from Switzerland, Sweden, Germany, the Czech Republic and the People's Republic of China. A DNA test is used to detect the bacterium in the patient's blood to confirm the infection.
Therapies with antibiotics led to a complete recovery in Swiss patients. The antibiotic doxycycline was administered, which is also used to treat Lyme disease .
Individual evidence
- ↑ a b c d e Makoto Kawahara, Yasuko Rikihisa, Emiko Isogai, Mamoru Takahashi, Hitoko Misumi, Chiharu Suto, Shinichiro Shibata, Chunbin Zhang and Masayoshi Tsuji: Ultrastructure and phylogenetic analysis of 'Candidatus Neoehrlichia mikurensis, isolated from the family in the wild rats and found in Ixodes ovatus ticks. International Journal of Systematic and Evolutionary Microbiology vol. 54 no. 5, 2004, pp. 1837-1843 doi: 10.1099 / ijs.0.63260-0
- ↑ a b c d e f G. Földvári G, S. Jahfari u. a .: Candidatus Neoehrlichia mikurensis and Anaplasma phagocytophilum in urban hedgehogs. In: Emerging Infectious Diseases. Volume 20, No. 3, March 2014, doi: 10.3201 / eid2003.130935 . online .
- ↑ a b c d e Jörg Zittlau: New pathogen discovered in ticks. In: RP Online website . June 4, 2014, accessed July 14, 2014 .
- ↑ a b c d e f g New tick disease in Switzerland. (No longer available online.) In: Press release from the University of Zurich . October 31, 2012, archived from the original on July 11, 2014 ; Retrieved July 14, 2014 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b A. Grankvist, PO Andersson u. a .: Infections with the tick-borne bacterium "Candidatus Neoehrlichia mikurensis" mimic noninfectious conditions in patients with B cell malignancies or autoimmune diseases. In: Clinical Infectious Diseases . Volume 58, No. 12, June 2014, pp. 1716-1722, ISSN 1537-6591 . doi: 10.1093 / cid / ciu189 . PMID 24647019 .
- ^ Jean Euzéby, Aidan C. Parte: Family Anaplasmataceae. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved July 14, 2014 .
- ^ Jean Euzéby, Aidan C. Parte: Some names included in the category Candidatus. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved July 14, 2014 .
