Bordetella

Genus of bacteria

Bordetella is a genus of small, Gram-negative, aerobic coccobacilli of the family Alcaligenaceae. The genus is named after the Belgian bacteriologist Jules Bordet, who, along with Octave Gengou, first isolated the bacterium responsible for whooping cough. Bordetella species are known for their role in causing respiratory infections in humans and animals.

Characteristics

Bordetella species are characterized by their small size and coccobacillary shape. They are strictly aerobic, meaning they require oxygen for growth, and are non-motile. These bacteria are oxidase positive and catalase positive, which are important biochemical characteristics used in their identification.

Pathogenic Species

The genus Bordetella includes several species, some of which are pathogenic to humans and animals:

• Bordetella pertussis: This species is the causative agent of pertussis, commonly known as whooping cough, a highly contagious respiratory disease. Bordetella pertussis produces several virulence factors, including the pertussis toxin, which plays a crucial role in the pathogenesis of the disease.

• Bordetella parapertussis: This species can cause a milder form of whooping cough in humans. It is similar to Bordetella pertussis but lacks some of the virulence factors.

• Bordetella bronchiseptica: This species primarily infects animals, causing respiratory diseases such as kennel cough in dogs and atrophic rhinitis in pigs. It can occasionally infect humans, particularly those with compromised immune systems.

• Bordetella holmesii: This species has been associated with bacteremia and endocarditis in humans, particularly in individuals with underlying health conditions.

Bordetella bronchiseptica

Virulence Factors

Bordetella species produce a variety of virulence factors that contribute to their pathogenicity. These include:

• Pertussis toxin: A major virulence factor of Bordetella pertussis, this exotoxin interferes with the host's immune response and contributes to the characteristic symptoms of whooping cough.

• Adenylate cyclase toxin: This toxin is produced by Bordetella pertussis and Bordetella bronchiseptica. It increases intracellular cAMP levels, disrupting cellular functions and aiding in immune evasion.

• Filamentous hemagglutinin: This adhesin helps the bacteria attach to the ciliated epithelial cells of the respiratory tract.

• Tracheal cytotoxin: This toxin damages the ciliated epithelial cells, leading to the characteristic cough associated with pertussis.

Pertussis toxin

Epidemiology

Bordetella pertussis is a significant cause of morbidity and mortality worldwide, particularly in infants and young children. Vaccination programs have significantly reduced the incidence of pertussis, but outbreaks still occur, often due to waning immunity or vaccine hesitancy.

Bordetella bronchiseptica is widespread in animal populations and can be transmitted between animals and occasionally to humans. It is a common cause of respiratory infections in dogs and pigs.

Prevention and Treatment

Vaccination is the primary method of preventing Bordetella pertussis infections. The DPT vaccine (diphtheria, pertussis, and tetanus) is commonly used in childhood immunization programs. Antibiotics such as macrolides are effective in treating Bordetella infections, particularly if administered early in the course of the disease.

Related pages

• Whooping cough
• DPT vaccine
• Respiratory tract infection