Bordetella parapertussis
Bordetella parapertussis is a bacterium of the genus Bordetella, which can cause similar symptoms whooping cough or acute bronchitis. There are small, gram -negative rods, which can be difficult to remove from related species Bordetella pertussis (also a pathogen of whooping cough ) and distinguish Bordetella bronchiseptica. The cells grow strictly aerobic, so need oxygen for their growth. For the cultivation of blood agar is often used, a culture medium with an addition of blood, this can be a hemolysis observed. The genome of the bacterial strain Bordetella parapertussis 12822 2003 was completely sequenced.
- 3.1 Outer systematics
- 3.2 Internal systematics
- 3.3 Etymology
- 4.1 pathogenicity
- 4.2 Sources of infection
- 4.3 Treatment and prevention
- 5.1 Literature
- 5.2 Notes and references
Features
Appearance
The cells of Bordetella parapertussis are short to coccoid rods. They are gram- negative. The cells are 0.8 microns long and 0.4 microns wide. The type is - as Bordetella pertussis - not motile, so it can not move independently. Endospores are not formed. The cells carry pili ( fimbriae ) on their surface and are surrounded by a capsule. They appear like other members of the genus Bordetella in the light microscopic image separately, stored in pairs or in groups and can be difficult to differentiate from Haemophilus species.
On solid media, the cells grow to very small colonies, they are transparent. Compared to B. pertussis colonies are slightly larger. On blood agar hemolysis takes place, this is also true for the related species B. pertussis, B. bronchiseptica and. However colonies of B. parapertussis capable of forming on peptone -containing culture media that do not contain blood, brown pigments. On nutrient media which contain tyrosine (an amino acid ), pigment formation is observed.
Growth and metabolism
The metabolism of Bordetella parapertussis is based on the breathing, the species is strictly aerobic, that requires oxygen to grow. The oxidase test is negative, catalase can be demonstrated, however. Furthermore, the metabolism is marked as chemoorganotroph and heterotrophic, B. parapertussis using organic compounds as an energy source as well as for the construction of cellular materials. In this case, it is asaccharolytisch, i.e. they can not sugars (eg glucose ) use, instead, include amino acids to the substrates which are degraded. This must be considered when choosing the appropriate culture medium for culturing.
The optimum temperature for growth is 37 ° C. Growth is carried out in a temperature range of 15-37 ° C, it takes about 10 days at 15 ° C. until colonies are visible at 37 ° C is usually 3-4 days incubation. At 44 ° C no growth occurs. B. parapertussis may contain small amounts of sodium chloride (table salt) tolerate in the nutrient medium. Growth is at a level of 3 % of sodium chloride also possible in 4.5% NaCl growth is variable and is at a level of 6 % or more, no growth occurs. It is not halophilic, as it can proliferate in the absence of sodium chloride. In the presence of bile salts is carried out growth, a content of 10% can be tolerated, while carried out at a content of 40 % of bile salts in the culture medium no growth.
Biochemical characteristics, such as the enzymes present and the resulting metabolic properties can be used in a colorful series for the identification of B. parapertussis. Besides the positive catalase and negative oxidase test the following features can be used: you does not conduct nitrate reduction, ie nitrate is not reduced to nitrite. The urease test is positive, the type having the urease enzyme, and thus is capable of degrading urea. Contrast, can not be degraded by hydrolysis of gelatin, casein or starch. Nor is it to Äskulinhydrolyse capable. It has the enzyme arginine dihydrolase ( ADH) and can therefore degrade the amino acid arginine. It can also degrade the amino acids L- glutamic acid and L -proline.
Other organic compounds which may be utilized as an energy source for setting up of cellular materials are citrate and pyruvate. Hydrogen sulfide ( H2S) is not formed. The Voges - Proskauer test for acetoin formation and indole test negative. Since no carbohydrates are broken down, there is also no acid formation, thus the methyl red test is also negative. The demarcation of B. pertussis and B. bronchiseptica is difficult because the three species in many metabolic and biochemical characteristics show similarities, but they can be distinguished on the basis of certain characteristics (see table).
Serological characteristics
Bordetella parapertussis has - on their cell wall superposed - lipopolysaccharide (LPS). These are part of the outer membrane, that is typical of gram-negative bacteria. Lipopolysaccharides are composed of fat-like elements connected to oligosaccharides ( sugar components ), which act as an antigen and may be used for the detection of serologically because they differ from the LPS of the related species. Furthermore, proteins are a part of the outer membrane, they are often abbreviated as OMP, according to the English designation outer membrane protein. They also act as an antigen and cause agglutination when they meet with the appropriate antibodies. For B. parapertussis, the corresponding protein is designated as AGG 14 (AGG abbreviation for agglutinin ), while the B. pertussis AGG 1 is typical. And the fimbriae act as antigens, they are designated at B. parapertussis as AGG 8, 9 and 10.
Genetics
12822 ( out under the number ATCC BAA -587 ) The genome of the bacterial strain Bordetella parapertussis was taken in 2003 completely sequenced. It is a strain which was founded in 1993 from a diseased child with whooping cough in Germany isolated. The genome has a size of 4774 kilobase pairs (kb ), which corresponds approximately to the size of the genome of Escherichia coli. There is a circular bacterial chromosome. There are 4185 proteins annotated.
B. parapertussis 18323 and B. parapertussis Bpp5 - - By 2013, the genome of two other strains was sequenced and published. The genome size coincides with 4044 or 4900 kb slightly smaller or larger than in the first studied strain. The results of sequencing show a high GC content ( the fraction of nucleic bases guanine and cytosine) in the bacterial DNA, it is at about 68 mole percent. The strain B. parapertussis Bpp5 was isolated from a sheep. Here, the genome also contains a plasmid. Referred to as BPP5P1 plasmid has a genome size of 12.2 kb. The function of its genes has not yet been conclusively, it is believed that they encode for proteins, inter alia, that are involved in replication and cell division. A plasmid has been found in any other Bordetella strain.
Evidence
For the cultivation of simple culture media are only suitable, but it grows on MacConkey agar. Frequent blood agar is used. In this case, hemolysis can detect if sheep blood is used in horse blood, this is not the case. A variant is the Bordet - Gengou blood agar, which still contains potato extract and glycerin. By the addition of penicillin it acts selectively as many Gram-negative bacteria in the growth can be inhibited by the antibiotic during Bordetella parapertussis resistant. Even better is the Regan - Lowe - Nähmedium containing activated charcoal (English charcoal) and blood (eg, cephalexin ) the bordetellae in a mixed flora provides a selective advantage by the addition of an antibiotic from the group of cephalosporins. After incubation for 3-4 days at 37 ° C, colonies can be recognized. The grown-up on the culture media bacterial culture can then be investigated biochemically to distinguish pertussis example, B. parapertussis from B..
For the analysis of clinical samples is the sampling time is of crucial importance, as in whooping cough, especially at the stage catarrhale the pathogens present in quantities that allow a culture test. As a sample, a swab is used with a swab from the nasopharynx ( nasopharyngeal ). Cotton swabs are not suitable, calcium alginate is used instead as the material. The swab must ( the Regan - Lowe - Nähmedium example ) are transported to the laboratory in a special culture medium.
Sometimes B. parapertussis is also detected using the direct immunofluorescence. It is based on the antigen detection, the antibody used is labeled with a fluorescent dye. As test material, a swab is used that contains the bacteria. Here, false-positive results occur and should be confirmed with a second method by non- species-specific antibodies. On the other hand, false negative results may occur if the number of pathogens is below the detection limit of the method. The sensitivity of the direct immunofluorescence assay is ideally about 60%. The more frequently used in clinical diagnosis by detection of an elevated level of antibodies is not suitable for early diagnosis of B. parapertussis, since specific antibodies in the serum at the earliest convulsivum the transition to the stage can be detected. Also may be present by vaccination or an earlier disease antibodies against pertussis toxin. A standard ELISA test is not yet available.
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, duplicated ( amplified ) and detected. A PCR test is quick to perform and more sensitive compared to the cultural methods. The difficulty is to find an appropriate gene segment, which is typical for B. parapertussis, but not found in the related species. 2013 developed a method based on the real-time quantitative PCR (q -PCR), while a fluorescent dye to be detected is attached 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 detection of bacteria. Developed in France method aimed at the detection of B. parapertussis and B. bronchiseptica, which can be detected and thus distinguished.
Occurrence
The habitat of Bordetella parapertussis are the ciliated epithelial cells of the human respiratory tract. Also it has been found in sheep.
System
Outer systematics
Bordetella parapertussis is one of several species of the genus Bordetella in the family of Alcaligenaceae, this will be provided to the order of the Burkholderiales in the class of the Betaproteobacteria. The genus Haemophilus, which has morphology similar to the Bordetella is provided to the class of Gammaproteobacteria, as well as the genus Acinetobacter, the B. parapertussis earlier was also assigned.
Inside systematics
From the genus Bordetella are the species B. parapertussis, B. pertussis and B. bronchiseptica since the first half of the 20th century known, other species have been rediscovered since 1984, as B. avium. The first discovered species resemble each other strikingly, so that a classification is discussed as a subspecies. They are also referred to as "classical " bordetellae. A comprehensive genetic study of seven bacterial strains brought 2012 new insights into the phylogenetic relationships. Only about 50% of the " core genome " (English pan- genome ) occurs in all strains, this diversity in the genome is a known cause for different hosts or different pathogenicity.
B. parapertussis was first described in 1938 by Grace Eldering and Pearl Kendrick and designated as Bacillus parapertussis. In 1952 the establishment of the genus Bordetella by Manuel Moreno López to which the bacterium is then detected. B. parapertussis is known by several synonyms, based on the fact that the bacterium (such as Bacillus or Haemophilus ) initially this was assigned because of its similarity to representatives of other genera. Synonyms are Bacillus parapertussis Eldering & Kendrick 1938, Haemophilus parapertussis ( Eldering & Kendrick 1938) Wilson & Miles 1946, Acinetobacter parapertussis ( Eldering & Kendrick 1938) Steel & Cowan 1964. From the species B. parapertussis (as of 2014) have been three bacterial strains genetically examined here, the strain B. parapertussis Bpp5 on the specificity of a plasmid. The strain B. parapertussis ATCC 9797 is the type strain of the article have been deposited several bacterial strains of B. parapertussis in various collections of microorganisms.
Etymology
The genus name was chosen in honor of the Belgian microbiologist Jules Bordet. The species name refers to the similarity to B. pertussis, para ( a Greek prefix ) means "close ", while pertussis from the Latin prefix per ("very ", " extremely " ) and the Latin word pertussis ( genitive " cough " ) composed. Pertussis is the medical term for whooping cough.
Medical importance
Bordetella parapertussis is next to B. pertussis, the pathogen responsible for whooping cough. Approximately 5-20 % of cases can be attributed to B. pertussis, which so often is accompanied by a milder disease course. Whooping cough is a disease with high mortality, especially for children under six years of labor. Since 2013 is in accordance with § 7 of the Infection Protection Act, a reporting requirement in the direct or indirect detection of B. parapertussis when evidence of acute infection points.
Pathogenicity
Bordetella parapertussis is ( " pathogenic " ) pathogenic for humans, it is the Biostoffverordnung in connection with the TRBA (Technical Rules for Biological Agents ) assigned 466 of risk group 2. Furthermore, it is noted in the classification that it is pathogenic for humans and vertebrates, but that usually does not transfer between the two host groups is present, it is therefore not a zoonotic agents. A bacterial strain was isolated from sheep.
Bordetella pertussis has many virulence factors, such as the filamentous haemagglutinin (FHA) and the pertussis toxin (PT), this is a protein which acts as an adhesin and exotoxin. Which are virulence factors also present in B. parapertussis, is the subject of research. In the genome of genes have been identified which code for the pertussis toxin, but these are not expressed, the protein thus formed. However, there are the heat labile toxin bronchiseptica, invasive adenylate cyclase, the tracheal cytotoxin (TCT ) and acting as an antigen and endotoxin lipopolysaccharides from the outer membrane of B. parapertussis, B. pertussis and B..
Sources of infection
The human respiratory tract is the habitat of Bordetella parapertussis. The route of infection is an airborne infection, the transmission of the pathogen is by droplet, the aushustet the sick.
Treatment and prevention
The use of antibiotics is only useful in the early stages of the disease, as long as pathogens are excreted by the patient. Frequently Erythromycin is used to interrupt the chain of infection. Other macrolide antibiotics, such as azithromycin, clarithromycin and roxithromycin are effective. Microbiological examinations by an antibiogram have the sensitivity of Bordetella parapertussis also compared with aminoglycoside antibiotics ( streptomycin and neomycin ), tetracyclines such as chlortetracycline ( Aureomycin ) and oxytetracycline ( Terramycin ), chloramphenicol, novobiocin and oleandomycin result ( a macrolide ). On the other hand, it is resistant to penicillins.
As a preventive measure is vaccination, which is recommended by the Standing Committee on Vaccination at the Robert Koch Institute. It should be started immediately after completion of the second month of life and continued at regular intervals.