Pathogens

Bordetella parapertussis – Infection, Transmission & Diseases

Bordetella parapertussis

The germ Bordetella parapertussis belongs to the genus Bordetella and is difficult to distinguish from the related germ Bordetella pertussis .

What is Bordetella parapertussis?

The bacterium Bordetella parapertussis owes its name to its genetic and biochemical similarity to the related germ Bordetella pertussis. The genus name Bordetella was used to commemorate the microbiologist Jules Bordet.

The germ has a short and coccoid rod shape. It is approximately 400 nanometers wide and 800 nanometers long and non-motile. It is gram-negative and therefore only has a murein shell with an overlying lipid layer.

Bordetella parapertussis has an aerobic metabolism and is unable to replicate without oxygen . The metabolism of the germ is therefore based on respiration.

Pili, which are also called fimbriae, are deposited on the bacterial envelope. Pili are burr-like branches that enable the bacterium to adhere to various surfaces. Endospores are not formed by the germ. Transmission only takes place via droplet infection by means of secretions ejected when coughing .

Amino acids , which are obtained through chemoorganotrophic specialization, are required to build up the cell’s own substances and as a source of energy . Citrates and puyruvates can also be included. The germ cannot utilize sugar and is therefore asaccharolytic. Sodium chloride and bile salts are tolerated by the germ in small amounts.

Enriching the culture media with 3% sodium chloride has no effect on the replication of the pathogen. Higher values ​​can block auto-replication. A bile salt content of up to 10% is easily tolerated. A value of 40% blocks replication completely.

A complete sequencing of the genome of the species Bordetella parapertussis was carried out in 2003. A strain isolated from a child in 1993 was used for this purpose. The size of the genome, at 4774 kilobase pairs, is roughly comparable to the size of the genome of the bacterial species Escherichia coli . Two other strains were sequenced by 2013. In the case of the strain Bpp5, which was isolated from a sheep, a plasmid with an unknown utility could be identified in the germ for the first time.

Occurrence, Distribution & Properties

Bordetella parapertussis only colonizes the epithelial cells of the respiratory tract. This is the tract that houses the airways and thus enables oxygen uptake .

The only way for the bacterium to find new hosts is through droplet infection .

For the metabolism of the germ, which is based on aerobic processes, the optimal conditions are created in the oxygen-rich respiratory tract.

Diseases & Ailments

Bordetella parapertussis and Bordetella pertussis are typical triggers of whooping cough. The germs trigger a moderate form of whooping cough and are responsible for 5-20% of the cases registered annually. The possibility of a really serious illness with fatal consequences exists in children up to the age of six. Due to the high risk of infection, an obligation to report the disease was introduced in 2013.

Classic whooping cough is divided into three stages, but infected people of all ages can also have atypical and persistent courses. After an incubation period of about 7-14 days, the catarrhal stage sets in. It is characterized by flu-like symptoms, a slight fever and an unproductive dry cough . The catarrhal stage lasts about two weeks, and infection via droplet infection is most likely here.

In the second stage, the convulsive stage, the typical symptoms of whooping cough appear. There is a rapid succession of attacks of coughing with a deep mucous tone, often with tongue sticking out and glassy sputum . There is also retching, which can lead to vomiting .

After the coughing fit, there is often a strong whoop in the lungs, which can also be heard in a reduced form during normal breathing of the infected person. The convulsive stage is the longest stage of whooping cough and can last from two to six weeks.

The third stage, the stage decrementi, describes the slow disappearance of the disease. The coughing attacks decrease and the deep and mucous sound recedes. Overall, the patient finds it much easier to cough. Gag reflexes and mucous sputum no longer occur to the same extent and the overall appearance of the disease slowly flattens out.

Since the lipopolysaccharides typical of gram-negative germs are stored on the cell wall and generate antibodies , an infection can be traced via these antibodies. The antibodies can also differentiate between the species Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica, since the lipopolysaccharides (LPS) of the individual species differ.

The proteins of the outer membrane and the fimbriae are suitable as further antigens (antibody generators). The proteins trigger agglutination (clumping) when they meet the corresponding antibodies.

A biochemical differentiation of the germs relevant to human medicine is difficult. However, the serological finding of the corresponding immunoglobulins (antibodies) offers the possibility of identifying the exact type of Bordetella germ. Unfortunately, this differentiation is not possible in the early stages of the infection, since no corresponding antibodies are formed here.

To make matters worse, active immunoglobulins can be confused with immunoglobulins from a past infection or vaccination . An uncertain diagnosis can be remedied by a subsequent polymerase chain reaction (PCR). For this purpose, gene segments that are present in smears of the patient are duplicated. These can then provide confirmation of the suspicion.

Another problem with Bordetella germs in the PCR is the genetic similarity of parapertussis and pertussis. Gene sequences that are characteristic of the individual bacterial strains are very difficult to identify. Further examination methods to improve the PCR, such as fluorescent light to better identify the gene sequences, are part of modern research.

Increased titer values ​​in combination with a positive PCR test offer at least a very high probability that it is the proven Bordetella species.

 

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.