Chlamydophila felis

Chlamydophila felis is a bacterium from the group of chlamydia and bacterial agents of cat flu, specifically the feline chlamydiosis. It was formerly considered a variant of the species Chlamydia psittaci, and established as a separate species in 1999. The genome of the strain Chlamydophila felis Fe/C-56 was completely sequenced in 2006.

• 3.1 Outer systematics
• 3.2 Internal systematics
• 3.3 Etymology

Features

Chlamydophila felis shows the typical characteristics of the group of chlamydia, so it can multiply within the cells of a host only intracellularly, ie. Like other chlamydiae it exists in the form of metabolically active elementary (EK ), which are important for the infection and as Netzkörperchen ( reticular, abbreviation RK ) live in the host cells. It is called a gram-negative bacterium, as it - is stained in the Gram staining by dyes used red - as elementary. This is normally caused by a thin murein layer (consisting of peptidoglycans ) in the cell walls, in contrast to the gram-positive bacteria have a thick murein layer. Genetic studies have demonstrated that the representatives of the family Chlamydiaceae possess genes that are required for the synthesis of peptidoglycan. However, the studies show that their cell walls contain only very small amounts or no peptidoglycan.

Because of the parasitic metabolism you can not cultivate the culture media commonly used in microbiology C. felis, instead you need cell cultures. Usually HeLa cells (human epithelial cells) in this case be used. For differentiation of Chlamydia species is the recognition of importance that C. felis can not produce glycogen as a storage material.

Genetics

The genome of the strain Chlamydophila felis Fe/C-56 was completely sequenced in 2006. This bacterial strain was isolated from a diseased conjunctivitis (eye inflammation) domestic cat. The genome has a size of 1174 kilobase pairs (kb ), which is only 25 % of the genome size of Escherichia coli. There are 1013 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 has this strain of C. felis to a plasmid with a genome size of 7.5 kb.

Pathogenicity

C. felis is assigned to 466 of the risk group 2 by the Biological Agents in connection with the TRBA and identified as zoonotic. This principle is pointed to the possibility that an infection can be transmitted between animals and humans directly or indirectly. In fact, some cases have been documented in which C. felis was transmitted from cats to humans.

Evidence

C. felis has - on its cell wall superposed - lipopolysaccharides. These compounds in grease-like elements connected to three sugar constituents act as an antigen and can be used serologically for the detection. More often, however, the proof is carried out in clinical diagnosis by an elevated titer of antibodies, but the antigens used in this case usually show other Chlamydophila or Chlamydia species on.

Much more specific detection of certain parts of the bacterial genome by means of the PCR method ( polymerase chain reaction). Here, gene segments, which are typical of the type of bacteria, reproduced and detected. A 2010 developed method is based on the Real Time Quantitative PCR ( q -PCR), while the fluorescent dye SYBR Green is used, which anneals to the gene segments and causes fluorescence. The strength of the fluorescence during a PCR cycle in real time recorded (hence the term real time) and used for the quantitative determination of the existing gene segments and thus a quantitative determination of the bacterial species. Developed in Japan procedure aims at the detection of Chlamydophila psittaci, but it can also be other animal pathogenic Chlamydophila species, including C. felis, so prove. It can also be used (for example, feces ), or cells infected clinical specimens, from which the extraction is carried out first of the DNA is performed with the Q -PCR.

Occurrence

The natural habitat of C. felis is the domestic cat, the pathogen is most detectable.

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 felis was the species Chlamydia psittaci ( now called Chlamydophila psittaci ) associated with the particularity that this bacterium is not as usually occurred in birds, but in cats. As a result of the investigations C. felis was classified as a separate species.

Inside systematics

The type Chlamydophila felis can be distinguished in several serotypes. So far is usual to distinguish different strains of bacteria. The investigations of Everett et al show that the tribes "FP Pring " and " FP Cello" have a plasmid, the trunk " FP Baker " is not. This strain is considered as the type strain for the species, it is also performed under the number ATCC VR -120. This strain is used as a live attenuated vaccine for the vaccination of cats.

Etymology

The species name refers to the occurrence, felis from the Latin meaning "cat" ( genitive ), thus refers to the domestic cat as the main host.

(Veterinary ) medical importance

C. felis is endemic in domestic cats and is with them a pathogen of conjunctivitis ( pink eye ) and rhinitis (runny nose ), more rarely, pneumonitis, especially in the context of cat flu.

The transferability to humans is possible, and so far only isolated cases have been scientifically documented. At a conjunctivitis in human patients Chlamydia trachomatis is often the pathogens. In a case study could be excluded through further examination of a patient with chronic conjunctivitis infection with C. trachomatis. This prompted the isolation of the pathogen and then the isolation of a bacterium from the cat of a patient. Both samples were found to Chlamydophila felis, so that a zoonotic disease is likely. The infection was successfully treated with the antibiotic doxycycline. In general for the treatment of infections with C. felis and related species used antibiotics from the group of tetracyclines and macrolides. Penicillin and other antibiotics with the same mode of action ( beta-lactam antibiotics) are ineffective because their site of action, the peptidoglycan, not with Chlamydophila is available.