Bordetella parapertussis

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Bordetella parapertussis
Systematics
Department : Proteobacteria
Class : Betaproteobacteria
Order : Burkholderiales
Family : Alcaligenaceae
Genre : Bordetella
Type : Bordetella parapertussis
Scientific name
Bordetella parapertussis
( Eldering & Kendrick 1938) Moreno-Lopez 1952

Bordetella parapertussis is a bacterium from the genus Bordetella that can cause whooping cough-like clinical pictures or acute bronchitis . They are small, gram-negative rods that are difficult to distinguish from the related species Bordetella pertussis (also a pathogen causing whooping cough) and Bordetella bronchiseptica . The cells grow strictly aerobically , so they need oxygen to multiply. Blood agar is oftenusedfor cultivation, a nutrient medium with the addition of blood, here hemolysis can be observed. The genome of the bacterial strain Bordetella parapertussis 12822 was completely sequenced in 2003.

features

Appearance

The cells of Bordetella parapertussis are short to cocoid rods . They are gram negative . The cells are 0.8 μm long and 0.4 μm wide. Like Bordetella pertussis , the species is not motile , so it cannot move on its own. Endospores are not formed. The cells have pili (fimbriae) on their surface and are surrounded by a capsule . Like other representatives of the Bordetella genus, they appear individually, in pairs or in groups in the light microscope image and are difficult to distinguish from Haemophilus species.

On solid culture media , the cells grow into very small colonies , these are transparent. Compared to B. pertussis , the colonies are slightly larger. On blood agar a place hemolysis place, this also applies to the related species B. pertussis and B. bronchiseptica . However, B. parapertussis colonies may form brown pigments on peptone- containing culture media that do not contain blood . Pigment formation can also be observed on culture media that contain tyrosine (an amino acid ).

Growth and metabolism

The metabolism of Bordetella parapertussis is based on breathing , the species is strictly aerobic , so it needs oxygen to grow. The oxidase test is negative, but catalase can be detected. Furthermore, the metabolism is to be characterized as chemoorganotrophic and heterotrophic , B. parapertussis uses organic compounds as an energy source and also to build up the cell's own substances. It is asaccharolytic, i.e. H. it cannot utilize sugar (e.g. glucose ); instead, amino acids are among the substrates that are broken down. This must be taken into account when choosing the right nutrient medium for cultivation.

The optimal temperature for growth is 37 ° C. Growth takes place in a temperature range of 15-37 ° C, at 15 ° C it takes about 10 days until colonies are recognizable, at 37 ° C incubation is usually 3-4 days . No growth occurs at 44 ° C. B. parapertussis can tolerate small amounts of sodium chloride (table salt) in the nutrient medium. Growth is possible with a content of 3% sodium chloride, with 4.5% NaCl the growth is variable and with a content of 6% or more there is no more growth. It is not halophilic as it can reproduce in the absence of sodium chloride. Growth also takes place in the presence of bile salts , a content of 10% is tolerated, while no more growth occurs with a content of 40% bile salts in the nutrient medium.

Biochemical characteristics, such as the enzymes present and the resulting metabolic properties, can be used in a colorful series to identify B. parapertussis . In addition to the positive catalase and negative oxidase tests, the following features can be used: It does not reduce nitrate, i. H. Nitrate is not reduced to nitrite . The urease test is positive, the species has the enzyme urease and is therefore able to break down urea . In contrast, gelatine , casein or starch cannot be broken down by hydrolysis . Nor is it capable of aesculin hydrolysis . It has the enzyme arginine dihydrolase (ADH) and can therefore break down the amino acid arginine . It can also break down the amino acids L - glutamic acid and L - proline .

Further organic compounds that can be used as an energy source and to build up the cells' own substances are citrate and pyruvate . Hydrogen sulfide (H 2 S) is not formed. The Voges-Proskauer test for acetoin formation and the indole test are negative. Since no carbohydrates are broken down, there is no acid formation either, so the methyl red test is also negative. Differentiation from B. pertussis and B. bronchiseptica is difficult because the three species show similarities in many metabolic-physiological and biochemical characteristics, but they can be differentiated on the basis of some characteristics (see overview ).

Serological characteristics

Bordetella parapertussis has - deposited on its cell wall - lipopolysaccharides (LPS). These are part of the outer membrane , which is typical for gram-negative bacteria. The lipopolysaccharides consist of fat-like components, combined with oligosaccharides (sugar components), which act as antigen and can be used serologically for the detection, as they differ from the LPS of the related species. Proteins are also part of the outer membrane; they are often abbreviated as OMP, after the English term outer membrane proteins . They also act as an antigen and cause agglutination when they meet the appropriate antibodies . In B. parapertussis the corresponding protein is referred to as AGG 14 (AGG an abbreviation for agglutinin), while AGG 1 is typical for B. pertussis . And the fimbriae also act as antigens; they are named AGG 8, 9 and 10 in B. parapertussis .

genetics

The genome of the Bordetella parapertussis 12822 bacterial strain (also known as ATCC BAA-587) was completely sequenced in 2003 . This is a strain that was isolated in 1993 from a child with whooping cough in Germany. The genome has a size of 4774 kilobase pairs (kb), which roughly corresponds to the genome size of Escherichia coli . It exists as a circular bacterial chromosome . There are 4185 proteins annotated .

By 2013, the genome of two other strains - B. parapertussis 18323 and B. parapertussis Bpp5 - had been sequenced and published. At 4044 and 4900 kb, the genome size is somewhat smaller or larger than that of the strain examined first. The results of the sequencing show a high GC content (the proportion of the nucleobases guanine and cytosine ) in the bacterial DNA ; it is around 68 mol percent. The B. parapertussis Bpp5 strain was isolated from a sheep . Here the genome also includes a plasmid . The plasmid designated BPP5P1 has a genome size of 12.2 kb. The function of its genes has not yet been conclusively clarified; it is assumed that they may a. code for proteins involved in replication and cell division . A plasmid has not yet been found in any other Bordetella strain.

proof

Regan-Lowe nutrient medium with activated charcoal and an addition of Cefalexin , in this example you can see colonies of Bordetella pertussis .

For cultivation simple culture media are only suitable, but it grows on MacConkey agar . Often, blood agar used. Haemolysis can be detected if sheep blood is used, but this is not the case with horse blood. One variant is the Bordet Gengou blood agar, which also contains potato extract and glycerine . The addition of penicillin makes it more selective , as the antibiotic inhibits the growth of many Gram-negative bacteria, while Bordetella parapertussis is resistant . The Regan-Lowe sewing medium, which contains activated carbon ( English charcoal ) and blood and which, by adding an antibiotic from the group of cephalosporins ( e.g. cefalexin ), gives the brothels a selective advantage in a mixed flora, is even more suitable . Colonies can be seen after incubation for 3-4 days at 37 ° C. The bacterial culture grown on the nutrient media can then be examined biochemically in order, for example , to differentiate B. parapertussis from B. pertussis .

The time at which the sample is taken is of decisive importance for the examination of clinical samples, since in whooping cough, especially in the catarrhal stage, the pathogens are present in the quantities that enable cultural detection. As the sample is a smear with a swab from the nasopharynx ( nasopharynx used). Cotton swabs are not suitable, calcium alginate is used as the material instead. The swabs must be transported to the laboratory in a special nutrient medium (e.g. Regan-Lowe suturing medium).

Sometimes B. parapertussis is also detected with the help of direct immunofluorescence . It is based on the antigen detection, the antibody used is a fluorescent dye labeled . A smear containing the bacteria is used as the test material. False positive results can occur here due to non-species-specific antibodies , which should be confirmed with a second method. On the other hand, false negative results can also occur if the number of pathogens is below the detection limit of the method. The sensitivity of the direct immunofluorescence test is ideally around 60%. The detection by means of an increased titer of antibodies, which is more frequently used in clinical diagnostics, is not suitable for the early diagnosis of B. parapertussis , since specific antibodies can only be detected in the serum at the earliest when the convulsive stage is reached. Antibodies to the pertussis toxin may also be present from a vaccination or previous illness. A standardized ELISA test is also not yet available.

The detection of certain parts of the bacterial genome using the PCR method ( polymerase chain reaction ) is much more specific . In this process, gene segments that are typical for the type of bacteria are duplicated ( amplified ) and detected. A PCR test can be carried out quickly and is more sensitive compared to the cultural methods. The difficulty here is to find a suitable gene segment that is typical of B. parapertussis but does not occur in the related species. A method developed in 2013 is based on Real Time Quantitative PCR ( q-PCR ), in which a fluorescent dye is attached to the gene segments to be detected and causes fluorescence. The strength of the fluorescence is recorded in real time during a PCR cycle (hence the term real time ) and is used for the quantitative determination of the gene segments present and thus a quantitative recording of the bacterial species. The method developed in France aims to detect B. parapertussis and B. bronchiseptica , which can be detected and distinguished from one another.

Occurrence

The habitat of Bordetella parapertussis are the ciliate-bearing epithelial cells of the human respiratory tract . It has also been found in sheep.

Systematics

External system

Bordetella parapertussis is one of several species from the genus Bordetella in the family of the Alcaligenaceae , this is placed in the order of the Burkholderiales in the class of the Betaproteobacteria . The genus Haemophilus , which has morphological similarity to the Bordetellen, is placed in the class of Gammaproteobacteria , as is the genus Acinetobacter , to which B. parapertussis was previously assigned.

Internal system

From the genus Bordetella , the species B. parapertussis , B. pertussis and B. bronchiseptica have been known since the first half of the 20th century; further species have been newly discovered since 1984, e.g. B. B. avium . The species discovered first are strikingly similar, so that classification as subspecies is being discussed. They are also known as “classic” brothels. A comprehensive genetic study of seven bacterial strains in 2012 brought 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 considered to be the cause of different hosts or different pathogenicity factors .

B. parapertussis was first described by Grace Eldering and Pearl Kendrick in 1938 and named Bacillus parapertussis . In 1952 the genus Bordetella was established by Manuel Moreno López , to which the bacterium was then placed. B. parapertussis is known by several synonyms based on the fact that the bacterium was initially assigned to these genera because of its similarity to representatives of other genera (such as Haemophilus or Bacillus ). Synonyms are Bacillus parapertussis Eldering & Kendrick 1938, Haemophilus parapertussis (Eldering & Kendrick 1938) Wilson & Miles 1946, Acinetobacter parapertussis (Eldering & Kendrick 1938) Steel & Cowan 1964. Three bacterial strains of the species B. parapertussis have been genetically (as of 2014) examined, the B. parapertussis Bpp5 strain has the peculiarity of a plasmid. The strain B. parapertussis ATCC 9797 is the type strain of the species. Several bacterial strains of B. parapertussis are deposited in various collections of microorganisms .

etymology

The generic 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 "next to", while pertussis is derived from the Latin prefix per ("very", "extreme") and the Latin word tussis ( genitive "cough") ) composed. Pertussis is also the medical term for whooping cough.

Medical importance

Bordetella parapertussis is, along with B. pertussis, the pathogen causing whooping cough. About 5–20% of the cases can be traced back to B. parapertussis , whereby a milder course of the disease is often associated. Whooping cough is a highly lethal disease, especially important for children under six years of age. Since 2013, according to Section 7 of the Infection Protection Act, there has been an obligation to notify the direct or indirect detection of B. parapertussis , provided the evidence indicates an acute infection .

Pathogenicity

Bordetella parapertussis is pathogenic for humans ("pathogenic"); it is assigned to risk group 2 by the Biological Agents Ordinance in conjunction with the TRBA ( Technical Rules for Biological Agents) 466 . The classification also states that it is pathogenic for humans and vertebrates, but that normally there is no transmission between the two host groups, meaning that it is not a zoonotic agent . One strain of bacteria was isolated from sheep.

Bordetella pertussis has numerous virulence factors , such as filamentous hemagglutinin (FHA) and pertussis toxin (PT), a protein that acts as an exotoxin and adhesin . What virulence factors are also present in B. parapertussis is the subject of research. Genes were identified in the genome that code for the pertussis toxin, but these are not expressed , so the protein is not produced. In contrast, the heat-labile toxin, the invasive adenylate cyclase , the tracheal cytotoxin (TCT) and the lipopolysaccharides acting as antigen and endotoxin are found from the outer membrane in B. parapertussis , B. pertussis and B. bronchiseptica .

Sources of infection

The human respiratory tract is the habitat of Bordetella parapertussis . The path of infection is a droplet infection , the pathogen is transmitted through droplets that the sick person coughs up.

Therapy and prevention

The use of antibiotics only makes sense in the early stages of the disease, as long as pathogens are still being excreted by the patient. Erythromycin is often used to break the chain of infection. Other macrolide antibiotics such as azithromycin , clarithromycin, and roxithromycin are also effective. Microbiological tests using an antibiogram have also shown the sensitivity of Bordetella parapertussis to aminoglycoside antibiotics ( streptomycin and neomycin ), tetracyclines such as chlortetracycline (aureomycin) and oxytetracycline (terramycin), chloramphenicol , novobiocin and oleandomycin . On the other hand, it is resistant to penicillins .

The vaccination against Bordetella pertussis , which is recommended by the Standing Vaccination Commission at the Robert Koch Institute , is a preventive measure . It should begin immediately after completing the 2nd month of life and be continued at regular intervals. There is no protective vaccination against Bordetella parapertussis as a preventive measure.

Reporting requirement

In Germany, direct or indirect evidence is subject to notification by name in accordance with Section 7 of the Infection Protection Act if the evidence indicates an acute infection. Laboratories etc. are required to report ( Section 8 IfSG).

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literature

  • Horst Finger, Carl Heinz Wirsing von König: Bordetella (Chapter 31) . In: Samuel Baron (Ed.): Medical Microbiology . 4th edition. University of Texas Medical Branch at Galveston, Galveston (TX), USA 1996, ISBN 0-9631172-1-1 ( NCBI Bookshelf ).

Individual evidence

  1. ↑ a b c d e f g h i j Herbert Hof, Rüdiger Dörries: Dual series: Medical microbiology . 3. Edition. Thieme Verlag, Stuttgart 2005, ISBN 978-3-13-125313-2 , p. 408-411 .
  2. ↑ a b c d e f g h Horst Finger, Carl Heinz Wirsing von König: Bordetella (Chapter 31) . In: Samuel Baron (Ed.): Medical Microbiology . 4th edition. University of Texas Medical Branch at Galveston, Galveston (TX), USA 1996, ISBN 0-9631172-1-1 .
  3. ↑ a b c d e f g h i Mardjan Arvand: Bordetellen . In: Helmut Hahn, Stefan HE Kaufmann, Thomas F. Schulz, Sebastian Suerbaum (eds.): Medical microbiology and infectious diseases . 6th edition. Springer Verlag, Heidelberg 2009, ISBN 978-3-540-46359-7 , p. 302-307 .
  4. ↑ a b c d e f g h R. Johnson, PHA Sneath: Taxonomy of Bordetella and Related Organisms of the Families Achromobacteraceae, Brucellaceae, and Neisseriaceae. In: International Journal of Systematic Bacteriology. Volume 23, No. 4, October 1973, pp. 381-404, ISSN  0020-7713 . doi : 10.1099 / 00207713-23-4-381 .
  5. ↑ F. von Wintzingerode, A. Schattke u. a .: Bordetella petrii sp. nov., isolated from an anaerobic bioreactor, and emended description of the genus Bordetella. In: International journal of systematic and evolutionary microbiology. Volume 51, No. 4, July 2001, pp. 1257-1265, ISSN  1466-5026 . doi : 10.1099 / 00207713-51-4-1257 . PMID 11491321 .
  6. ↑ a b c K. Kersters, K.-H. Hinz u. a .: Bordetella avium sp. nov., Isolated from the Respiratory Tracts of Turkeys and Other Birds. In: International Journal of Systematic Bacteriology. Volume 34, No. 1, January 1984, pp. 56-70, ISSN  0020-7713 . doi : 10.1099 / 00207713-34-1-56 .
  7. ↑ Bordetella parapertussis 12,822th In: Website Genomes Online Database (GOLD) . Retrieved February 25, 2014 .
  8. ↑ a b Bordetella parapertussis. In: National Center for Biotechnology Information (NCBI) Genome website . Retrieved February 25, 2014 .
  9. ↑ a b c d e J. Park, Y. Zhang u. a .: Comparative genomics of the classical Bordetella subspecies: the evolution and exchange of virulence-associated diversity amongst closely related pathogens. In: BMC genomics. Volume 13, October 2012, p. 545, ISSN  1471-2164 . doi : 10.1186 / 1471-2164-13-545 . PMID 23051057 . PMC 3533505 (free full text).
  10. ↑ a b c d e pertussis (whooping cough) - RKI guide for doctors. In: Website of the Robert Koch Institute (RKI) . June 26, 2013, accessed February 27, 2014 .
  11. ↑ A. Tizolova, D. Brun et al. a .: Development of real-time PCR assay for differential detection of Bordetella bronchiseptica and Bordetella parapertussis. In: Diagnostic microbiology and infectious disease. [electronic publication before printing] January 2014, ISSN  1879-0070 . doi : 10.1016 / j.diagmicrobio.2013.12.020 . PMID 24525142 .
  12. ^ A b c Jean Euzéby, Aidan C. Parte: Genus Bordetella. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved February 26, 2014 .
  13. ^ Jean Euzéby, Aidan C. Parte: Phylum "Proteobacteria". In: List of Prokaryotic names with Standing in Nomenclature Systematics of Bacteria (LPSN) . Retrieved February 26, 2014 .
  14. ↑ M. Moreno-López: El genero Bordetella [The genus Bordetella]. In: Microbiologia Española. Volume 5, 1952, pp. 177-181.
  15. ↑ Taxonomy Browser Bordetella parapertussis. In: National Center for Biotechnology Information (NCBI) website . Retrieved February 26, 2014 .
  16. ↑ Strain Passport Bordetella pertussis. In: StrainInfo website (information collected about bacterial strains in over 60 biological resource centers (BRCs)). Retrieved February 26, 2014 .
  17. ↑ TRBA (Technical Rules for Biological Agents) 466: Classification of prokaryotes (Bacteria and Archaea) into risk groups. In: Website of the Federal Institute for Occupational Safety and Health (BAuA). April 25, 2012, p. 42 , accessed January 7, 2014 .