Bordetella

Bordetella bronchiseptica ( Scanning electron micrograph )

Bordetellae are bacteria belonging to the genus Bordetella. It is Gram-negative, short rods shaped cells that usually grow obligately aerobic. Almost all species of parasite on humans, animals or birds, some of them are pathogens, the best known being the triggered mainly by Bordetella pertussis whooping cough.

Features

Appearance

The cells of Bordetella species are short to coccoid ( spherical ) rods in the Gram stain, they behave gram negative. In light microscopic image they appear individually, stored in pairs or in groups. Endospores are not formed. The cells carry pili ( fimbriae ) on their surface. Only a few species move independently, they are motile.

Growth and metabolism

It almost always is strictly aerobic bacteria, their metabolism is based on the breathing, they need oxygen to grow. An exception Bordetella petrii group which may also grow anaerobically. They multiply well at temperatures in the range of 30-37 ° C. The catalase test is positive. Bordetella species asaccharolytisch, i.e., they can not sugars (for example glucose) use. All types can utilize citrate under aerobic conditions as an energy source and to build cell- own substances.

Gelatin can not be degraded by hydrolysis, it also finds no Äskulinhydrolyse instead. The Voges - Proskauer test for acetoin formation and indole test negative. However, they may reduce the redox dye tetrazolium to its colored form. For many Bordetella species is suitable for the cultivation of Bordet - Gengou blood agar and the Regan - Lowe Nähmedium, wherein said activated carbon comprises (see evidence of B. parapertussis ).

The demarcation of the first discovered species is difficult because the three species in many metabolic and biochemical characteristics show similarities, they can be distinguished, however, by the following features. With the discovery of other Bordetella species, these distinguishing features have been enhanced.

For some tests, no data ( nd a ) are present in the species, a variable result is due to the fact that behave the bacterial strains of a species different.

Chemotaxonomic features

The GC content (the proportion of nucleobases guanine and cytosine ) is located in the bacterial DNA between 60 and 69 mole percent. The main menaquinone is Q -8. Vandamme et al examined as part of the first description of Bordetella trematum the composition of fatty acids in the membrane lipids and compared them with the known species. Thus, in Bordetella species no branched chain fatty acids occur. A few typical fatty acids in the cell membrane can not be determined, in large quantities, however, (in each case more than 30 %) are the fatty acids with the abbreviations C16: 0 ( palmitic or hexadecanoic acid ) and C17: 0 cyclo available. For C17: 0 cyclo is heptadecanoic acid containing in the carbon chain, a ring (as in the cycloalkanes ), such fatty acids are also typical of members of the genus Alicyclobacillus. Also is found in several species studied Bordetella Lactobacillsäure, but only in a small amount of 1-2%.

Pathogenicity

Bordetellae are often pathogenic ( " pathogenic " ) and infected the ciliated epithelium of the respiratory tract of mammals, humans and birds. Except as petrii ( risk group 1) All other species are represented by the Biological Agents in connection with the TRBA (Technical Rules for Biological Agents ) assigned 466 of risk group 2. In some species, however, is noted in the classification that it is pathogenic for humans and vertebrates, but that usually does not transfer between the two host groups occurred or that a man is not affected under natural conditions.

System

For the first time a bacterium of this genus ( Bordetella pertussis ) in 1906 by the Belgian microbiologist Jules Bordet and Octave Gengou was isolated. The first discovered species were often initially other genera ( eg, Bacillus, Haemophilus, or Alcaligenes ) assigned. In 1952 the establishment of the genus Bordetella by Manuel Moreno López to which the bacteria were then placed. The genus name honors Jules Bordet. Bordetella pertussis is the type species of the genus. Currently ( 2014) the genus includes the following species (species):

• Bordetella avium Kersters et al. 1984 - Host: birds, especially poultry, such as turkeys
• Bordetella bronchiseptica ( Ferry 1912) Moreno - López 1952 - Host: different mammals
• Bordetella hinzii Vandamme et al. 1995 - Host: poultry, nonpathogenic there, but occasionally triggers disease in people from
• Bordetella holmesii Weyant et al. 1995 - Host: man, in the blood
• Bordetella parapertussis ( Eldering & Kendrick 1938) Moreno - López 1952 - Host: Human, causative agent of whooping cough ( mild form )
• Bordetella pertussis ( Bergey et al 1923. ) Moreno - López 1952 - Host: Human, causative agent of whooping cough
• Bordetella petrii of Wintzingerode et al. 2001 - the only representative of the genus, which has been isolated from the environment and grow under anaerobic conditions,
• Bordetella trematum Vandamme et al. 1996 - Host: person, in open wounds and ear infections

B. pertussis, B. parapertussis and B. bronchiseptica have been known since the first half of the 20th century, they are also referred to as "classical " Bordetella species. They are genetically so closely related that they are discussed as a subspecies of the same species. Phylogenetic studies to elucidate the kinship relations of organisms to one another mainly include the sequencing of the 16S rRNA, a typical representative for prokaryotes the ribosomal RNA. This shows that the genus Bordetella forms a separate group with the genera Achromobacter and Alcaligenes as more closely related groups. Within the bordetellae example shows petrii trematum the largest deviations ( 97.9 to 98.6 % similarity in the sequence), followed by B. avium ( 98.7 to 98.8 %) and B..