Bordetella is a genus of bacteria. The bacteria that belong to this genus are called bordetella. The best-known pathogen in this group of bacteria is Bordetella pertussis.
What are bordetella?
The first bacteria from the Bordetella genus were isolated in 1906 by microbiologists Octave Gengou and Jules Bordet. The group was not established until 1952 by Manuel Moreno Lopez. The genus, however, was named after Jules Bordet. Bordetells are gram-negative bacteria. They can be stained red in the Gram stain. Unlike Gram-positive bacteria, Gram-negative bacteria have an additional outer cell envelope. The distinction between gram-positive and gram-negative plays an important role in therapy when choosing the right antibiotic. The short rod-shaped bacteria grow obligately aerobically. This means that the bordetelles require oxygen to live. They convert this in energy metabolism. Bordetella petrii is an exception. This bacterium can also grow anaerobically. Bordetella proliferate especially in the temperature range of 30 to 37 °C. The bacteria are asaccharolytic, i.e. they cannot utilize sugars, but use citrate as an energy source. Almost all Bordetalla species live parasitically. Preferred hosts are humans, birds, and other animals. Some of the Bordetella are known pathogens. These include Bordetella pertussis, for example. Bordetella pertussis is the causative agent of whooping cough. Currently, the species Bordetella avium, Bordetella bronchiseptica, Bordetella hinzii, Bordetella holmesii, Bordetella parapertussis, Bordetella petrii, Bordetella trematum and Bordetella pertussis belong to the Bordetellen Many of them are important in veterinary medicine. The bacteria Bordetella pertussis, Bordetella parapertussis and Bordetelle bronchiseptica are referred to as classical Bordetella. They are genetically very closely related, so they are sometimes classified as subspecies of the same bacterial species.
Occurrence, distribution, and characteristics
Bordetella are found worldwide. Pertussis (whooping cough), caused by the pathogens Bordetella pertussis and Bordetella parapertussis, occurs year-round. However, there are more cases of the disease in autumn and winter. Humans are the only pathogen reservoir for Bordetella pertussis and Bordetella parapertussis. In addition, the pathogens are also found in sheep. The other bacteria from the Bordetella group are also found in birds and other mammals. Bordetella pertussis and Bordetella parapertussis are highly contagious. Infection occurs via droplet infection. Through close contact with infectious individuals, large contaminated droplets are transmitted within a distance of up to one and a half meters by sneezing, coughing, or talking. Contagiousness begins at the end of the incubation period, which usually lasts between nine and ten days. However, ranges of six to twenty days have been reported. Contagiousness can last for several months.
Diseases and symptoms
Bordetella pertussis and Bordetella parapertussis cause whooping cough (pertussis). The disease can be divided into three stages. The first stage, the catarrhal stage, lasts between one and two weeks. Infected individuals develop flu-like symptoms such as a mild cough, runny nose, fatigue and weakness. No fever or only a very mild fever occurs. The second stage is also called stage convulsivum. It lasts between four and six weeks and is characterized by the typical whooping cough. This intermittent, severe cough is also known as a staccato cough. The coughing episodes are followed by a so-called inspiratory dragging. Affected individuals try to breathe against the closed epiglottis at the end of the attack. This results in wheezing sounds. As part of the coughing attacks, sufferers often regurgitate viscous mucus. The coughing attacks may also be accompanied by vomiting. The cough occurs more frequently at night. During the day, there may be very many attacks. Fever is also very mild or completely absent at this stage. If higher fever is present, this can be taken as an indication of a secondary bacterial infection. Coughing in pertussis is not helped by cough suppressant medications. The final stage is the decrementi stage. It can last up to ten weeks. In this stage, the coughing attacks slowly subside.In adults or adolescents, whooping cough often progresses as a prolonged cough. However, the typical attacks of whooping cough are sometimes completely absent. Infants also show a different clinical picture. Infants and very young children unfortunately tend to suffer from sneezing attacks. These are not infrequently accompanied by respiratory arrest (apnea). Infants also have a very high risk of suffering severe complications. The most common and also most dangerous complication is pneumonia. It is usually caused by superinfection with Haemophilus influenzae. Other complications include middle ear infections, sinusitis, incontinence, and hernias caused by the high pressure during the coughing fits. In addition, rib fractures and bleeding in the conjunctiva and even the brain can occur. Antibiotic therapy does not affect the severity and duration of the coughing attacks in Bordetella pertussis or Bordetella parapertussis infections. This is because antibiotics are usually given too late and the respiratory epithelium has already been too severely damaged by the bacteria. Antibiotics are used only while the patient is still excreting bordetella. Various vaccines are available in Germany for the prophylaxis of pertussis. The Standing Commission on Vaccination (STIKO) stipulates vaccination against pertussis for the second month of life. Another vaccination is given between the 11th and 14th month of life.
