Chlamydophila psittaci
Chlamydophila psittaci ( staining by direct immunofluorescence with fluorescent antibodies (FA) )
Chlamydophila psittaci, formerly known as Chlamydia psittaci is a bacterium from the group of chlamydia and the causative agent of ornithosis. The genome of nine strains of Chlamydophila psittaci 2012 has been completely sequenced.
- 3.1 Outer systematics
- 3.2 Internal systematics
- 3.3 Etymology
- 5.1 Literature
- 5.2 Notes and references
Features
Chlamydophila psittaci shows the typical characteristics of the group of chlamydia. Like all Chlamydia psittaci C. can only intracellularly, i.e., multiply within the cells of a host, as the bacteria can not synthesize nucleotides. The other biological properties correlate well with other chlamydiae (qv). A special feature is that C. psittaci can remain infectious in the form of small Überdauerungsformen, so-called elementary bodies for weeks outside a host organism.
Genetics
The genome of Chlamydophila psittaci 6BC strain of 2011 was completely sequenced. The genome has a size of 1179 kilobase pairs (kb ), which is only 25 % of the genome size of Escherichia coli. There are 975 proteins annotated. The small genome size is an indication of the parasitic life, the bacterium has over time lost the ability to synthesize a number of metabolites, as it receives this by the host cells. The results of sequencing shows a GC content ( the fraction of nucleic bases guanine and cytosine) in the bacterial DNA of about 39 mole percent. In addition to the bacterial chromosome of this strain of C. psittaci has also a plasmid with a genome size of 7.5 kb.
2012 was followed by a genetic study of all nine known strains ( nine different genotypes) of C. psittaci. The size of the genome varies 1141-1172 kb, except for one strain of bacteria all exhibit also an extrachromosomal plasmid. The GC content in the bacterial DNA is 38.7 to 39.1 mole percent.
Pathogenicity
C. psittaci is assigned to 466 of the Risk Group 3 by the Biological Agents in connection with the TRBA and identified as zoonotic. A transmission of C. psittaci from animals to humans is readily possible.
Evidence
The detection of certain parts of the bacterial genome may be carried out using the PCR method ( polymerase chain reaction). A 2010 developed method is based on the Real Time Quantitative PCR ( q -PCR) and allows the quantitative determination of C. psittaci and other animal pathogens Chlamydophila species, such as C. felis.
Occurrence
The natural reservoir of C. psittaci are birds, especially parrots (see name). In these, the infection can cause serious illness or death, or even cause only minor symptoms or remain inapparent. The 2012 known genotypes of C. psittaci were isolated from the following birds: cockatoos, parakeets, lories and other parrots, pigeons, ducks, geese, turkeys and ratites. Some strains were also found in humans, domestic cattle and muskrats.
System
Outer systematics
The systematics of the order Chlamydiales - and thus also of the genera Chlamydia and Chlamydophila - has fundamentally changed by the work of Everett, inter alia, from the year 1999. Before Chlamydophila psittaci was called Chlamydia psittaci and Chlamydia trachomatis together formed with the genus Chlamydia. However, genetic studies showed significant differences between the two types, so that a new genus Chlamydophila was established with C. psittaci as the type species. By publication in the International Journal of Systematic and Evolutionary Microbiology ( IJSEM ), a new taxon, such as genus or species is validated, ie is determined valid. Although this was done for Chlamydophila psittaci in 1999, can be found partly in the literature still the obsolete name.
Inside systematics
Chlamydophila psittaci The type can be distinguished in several bacterial strains. To elucidate the evolutionary history - and the family relationships of organisms to each other - we examined the DNA sequences in bacteria and in addition, the 16S rRNA, a typical representative for prokaryotes the ribosomal RNA. In the studies by Everett et al 1999 eight strains were distinguished and named eight serovars. The results show that the genes of the 16S rRNA gene of these strains differ by less than 0.6 % of each other. The strain 6BC is considered as the type strain for the species, it is also performed under the number ATCC VR -125. The genetic studies of Van Lent et al 2012 were nine bacterial strains to reason that are regarded as representatives of nine genotypes. These correspond to the serovars, except that with genotype E / B, another is added. The names of the strains are, however, different, because they are included in part is not in the significant collections of microorganisms (such as the ATCC). Thus, the results can not easily be compared. All strains studied are (for the host animals ) to be regarded as pathogenic, and as a pathogen readily transmissible to humans.
Etymology
The species name refers to the occurrence, psittaci from the Latin meaning " the parrot " ( genitive ), thus refers to the parrots ( Psittaciformes ) as the main host.
Clinical Significance
In Germany, an estimated 200 people a year suffer from the ornithosis. As a rule, these are decorative bird owners or breeders. For this and for workers in poultry farms is the ornithosis ( psittacosis or ) recognized as an occupational disease.