Campylobacter coli

Campylobacter coli is a microaerophilic, gram-negative bacterium of the genus Campylobacter. It is closely related to Campylobacter jejuni, both types have been assigned to the genus Vibrio and before the pathogen Campylobacter enteritis, inflammatory diarrheal disease in humans. They are transmitted from animals on food and drinking water to the people.

The species comprises about 90 tribes. The genome of several strains was completely sequenced in 2013. In addition to the bacterial chromosome and plasmids within the cell may be included. A -studied plasmid contains several genes for antibiotic resistance, and that gives the bacteria resistance to gentamicin and other antibiotics.

• 3.1 Outer systematics
• 3.2 Internal systematics
• 3.3 Etymology

• 4.1 Sources of infection
• 4.2 infectious diseases
• 4.3 therapy

Features

Appearance

The cells of Campylobacter coli are slender, spirally curved rods that are 0.2-0.8 microns ( micrometers) thick and 1-5 microns long. Also, comma-shaped curved rods occur. Located at both poles, a single flagellum, thus a active cell movement possible. In the Gram stain they behave negatively. There shall be no Überdauerungsformen as endospores.

Growth and metabolism

Campylobacter coli is one of the microaerophilic bacteria. It requires oxygen for growth, but at lower concentrations than are contained in the air. He runs an aerobic metabolism and is catalase - positive and oxidase -positive. For the cultivation of a gas atmosphere is often used, the less of oxygen (O2), and more carbon dioxide (CO2 ) as the air. A gas mixture used for this purpose is composed of 5 % O2, 10 % CO2 and 85% nitrogen (N2). A similar gas atmosphere that is used in the analysis of Campylobacter coli, containing 5% O2, 3.5% CO2, 7.5% hydrogen (H2), and 84 % N2. Incubation usually takes place at 37 ° C, even at 42 ° C but growth still takes place, not at 25 ° C. He is counted among the thermophilic Campylobacter species.

Some enzymes that are used in metabolism to degrade certain substrates, as well as other metabolic reactions are detected as part of a "colorful series", to identify a bacterium. Campylobacter coli has catalase and oxidase, and, with the aid of the enzyme nitrate reductase (NADH ) (EC 1.7.1.1 ) to reduce nitrate to nitrite. It can grow in a nutrient medium containing 1% glycine and tolerates a proportion of glucose in the medium of up to 8 %. An important feature to distinguish the different Campylobacter species is the test of formation of hydrogen sulfide (H2S). This test can be performed with the TSI agar ( Triple Sugar Iron Agar, English for triple sugar iron agar ). Here Campylobacter coli shows no clear result, that is, it can be a positive or a negative result in the test occur. On nutrient media containing an addition of blood (so-called blood agar ), an alpha - hemolysis is observed.

Important for the effect as the pathogen is a resistance of the bacteria to antibiotics. In the U.S., the bacterial strains are examined from clinical samples and since 2002 also from meat samples from retail stores on a regular basis for resistance to aminoglycoside antibiotics towards since 1996. As a result of this monitoring was 2000 discovered against gentamicin resistant Campylobacter coli ( isolated from a human), followed by a 2007 isolate from chicken meat. 2010 11.3% of the people and 12.5 % of the isolated strains of meat samples were resistant to gentamicin. The insensitivity to nalidixic acid, the first antibiotic in a group of quinolones, was described in 1973 by Véron and Chatelain. They succeeded in cultivation on a blood agar supplemented with 40 ug / ml of nalidixic acid.

Genetics

The genome of three strains has been completely sequenced (as of 2013). The bacterial strain Campylobacter coli CVM N29710 used for an investigation was isolated from a poultry meat sample from the retail sector. The genome of the bacterial chromosome has a size of 1673 kilobase pairs (kb ), which is about 35% of the genome size of Escherichia coli. In addition to the chromosomes and two plasmids were sequenced, and the smaller with a size of 3.7 kb, the larger 55.1 kb. A total of 1694 proteins are annotated. The results of the sequencing show a GC content ( the proportion of nucleobases guanine and cytosine) in the bacterial DNA from 31.4 to 31.9 mole percent. This is within the range of 30-38 mole percent, which is typical for the genus Campylobacter, a representative of the class of Epsilonproteobacteria. Campylobacter coli and some related species were formerly attributed to the genus Vibrio. This counted for the class of Gammaproteobacteria bacteria exhibit a significantly higher GC content, eg 47 mole percent of Vibrio cholerae. This proves that Campylobacter coli is not more closely related vibrios.

The investigation of the isolated from poultry meat tribe also includes the present in the genome plasmids. One of the two plasmids contains several genes for antibiotic resistance, and that gives the bacteria resistance to multiple aminoglycoside antibiotics ( gentamicin, kanamycin, streptomycin, streptothricin ) and tetracyclines. The plasmid can be transferred from one bacterial cell to another, so that the resistance genes are transferred.

Pathogenicity

Campylobacter coli is determined by the Biological Agents in connection with the TRBA (Technical Rules for Biological Agents ) assigned 466 of risk group 2 and identified as zoonotic. Thus, attention is drawn to the possibility that an infection can be transmitted between animals and humans directly or indirectly.

The mechanisms of pathogenicity of the pathogen are still the subject of research. Campylobacter coli cytolethal distending toxin forms the so-called ( CDT), translated as cytolethales ( deadly for cells), intumescent toxin. This toxin consists of several units, one of which shows a DNase activity, and is therefore able to break down the DNA. CDT is engaged in the process of cell division, the result is increased, acting as inflated cells, for this phenomenon is the toxin designated. The coding for this virulence factor genes CDTA, CDTC CDTB and were the subject of an investigation published in 2010. Case 242 isolates from food and 112 isolates from clinical specimens were examined for these genes that. In all bacterial strains from clinical samples all three genes could be detected in the Lebensmittelisolaten the CDTA and CDTC genes in 99.4 % of the strains and the CDTB gene in 98.8 % of the strains were detected.

Evidence

Campylobacter coli is usually cultivated on or in complex nutrient media. These contain, for example meat extract and yeast extract, peptone, and sodium chloride (NaCl). This medium can be additionally treated with 10 % blood. Also suitable for cultivation of the Muller-Hinton agar supplemented with 5 % horse blood. The addition of blood allows the assessment of whether the bacterium performs hemolysis. The colonies grown on these media must be examined for further identification. Biochemical tests for identification include the catalase and oxidase test, and typical tests of a "colorful series". A work based on the rapid determination system in miniature (Analytical Profile Index ) for the determination of Campylobacter species is commercially available.

Serological tests for the identification can also be used that are based on antigen -antibody reaction. Antibodies required is obtained from the blood serum of mice immunized with the purified membrane proteins of the Campylobacter species. However, the antibodies are not specific to a single antigen. More specifically, the detection of certain parts of the bacterial genome by means of the PCR method is ( polymerase chain reaction). Here is a typical for the genus species-specific gene next to genes is determined. The detection is performed using the multiplex PCR method and allows the differentiation of Campylobacter coli and Campylobacter jejuni.

Occurrence

Campylobacter coli is normally found in the intestines of pigs and poultry and other birds. Occasionally he is also detectable in the human gut. In sheep and cattle would not normally be part of the intestinal flora.

System

Outer systematics

Campylobacter coli is a typical representative of the genus Campylobacter. Next to him are the species C. jejuni and C. lari of medical importance for humans, whereas C. fetus is more of veterinary importance. Campylobacter coli and Campylobacter jejuni are closely related and similar in many features, so that a distinction depending on the method of examination is not always possible. Therefore, they are recorded together as Campylobacter jejuni partially in medical microbiology. In another kind - Campylobacter hyoilei - is not yet clear whether he maintains the status as a distinct species, or whether it is a variant of Campylobacter coli.

Succeeded in 1973 the secure distinction from Vibrio and Campylobacter species, Campylobacter coli has been previously described as Vibrio coli. This is due to the appearance of cells that occur in addition to the spirally curved shape as a comma-shaped curved rods, which is typical of vibrios.

Inside systematics

The type includes about 90 tribes. The genome of several strains has already been completely sequenced or is being explored in other genome projects. Campylobacter coli ATCC 33559 is the species- typical strain. The far unidentified strains studied have two plasmids ( Campylobacter coli CVM N29710 ), a plasmid ( Campylobacter coli 15-537360 ) or no plasmid ( Campylobacter coli 76339 ).

Etymology

The genus name refers ( kampylos = crooked ancient Greek καμπὓλος, βακτηρΐα bacteria = rod) on the appearance of the bacterial cells, ie curved or bent rods. The species name refers to the occurrence, coli from the Latin meaning ' of the intestine " ( genitive ), thus refers to the gut as a habitat.

Medical importance

Sources of infection

The infection of Campylobacter coli is usually administered orally, in most cases happens uptake via contaminated food and drinking water. Infections while bathing in contaminated surface waters ( lakes and other standing waters in summer ) occur. Rarely done the direct fecal- oral transmission from person to person. Individual cases of transmission of diseased people to others in a community setting are documented, with Dauerausscheidern is usually not expected. In immunocompromised persons, it may lead to a long-term excretion. A direct smear infection occurs, especially in children. Often the infection occurs in the summer.

The bacteria can spend some time in the environment or in food to survive, while it does not multiply. Already receiving a rather small amount of Campylobacter coli sufficient to cause infection in children it is possible already at a dose of infection of approximately 500 bacterial cells. The amounts made ​​as sources of infection foods are mainly contaminated by excreting animals. Case studies are insufficiently heated or contaminated poultry meat has been recognized as the most important source of infection. Other sources of infection are unpasteurized milk, contaminated, not treated drinking water and raw ground beef. The transfer by pets (especially by falling sick puppies and cats ) or contact with their excreta ( faeces) is possible.

Infectious diseases

After an incubation period of 1 to 7 days, the following symptoms may be noticeable:

• Severe, colicky abdominal pain
• Watery diarrhea, often with mucus, sometimes with blood deposits
• Fever up to 40 ° C.

In Germany and Austria must be reported, it engages in Germany the Infection Protection Act (IfSG ). According to § 7 ​​of the Infection Protection Act, a reporting requirement for the positive detection of pathogens by -detecting lab with a roll-call notification of the patient. According to § 6 IfSG the disease as acute infectious gastroenteritis is reportable if an epidemic context, it is likely or is suspected. According to § 42 IfSG an activity and employment prohibition for the affected person is in certain food businesses.

Therapy

Most infections are self-limiting after a few days. Under certain circumstances, an antibiotic is needed here Erythromycin is the drug of choice. Quinolones are only moderately effective.