Bordetella

Bordetella pertussis

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Diagram of the pertussis toxin structure

Bordetella pertussis is a Gram-negative, aerobic, pathogenic bacterium of the genus Bordetella. It is the causative agent of whooping cough (pertussis), a highly contagious respiratory disease. The bacterium is known for its ability to produce a variety of virulence factors, including the well-known pertussis toxin.

Characteristics

Bordetella pertussis is a small, encapsulated coccobacillus. It is non-motile and strictly aerobic, requiring oxygen for growth. The bacterium is fastidious, meaning it requires specific nutrients and conditions to grow in laboratory settings. It is typically cultured on Bordet-Gengou agar or Regan-Lowe medium.

Pathogenesis

Bordetella pertussis infects the respiratory tract of humans, its only known host. The infection process begins when the bacterium attaches to the cilia of the epithelial cells in the upper respiratory tract. This attachment is mediated by several adhesins, including filamentous hemagglutinin and pertactin.

Once attached, Bordetella pertussis releases toxins that interfere with the host's immune response and damage the respiratory epithelium. The most notable of these toxins is the pertussis toxin, which disrupts cellular signaling pathways and contributes to the characteristic symptoms of whooping cough.

Clinical Manifestations

The disease caused by Bordetella pertussis is characterized by severe coughing fits, which can be followed by a "whooping" sound as the patient breathes in. The disease progresses through three stages:

• Catarrhal stage: Resembles a common cold with mild cough and runny nose.
• Paroxysmal stage: Severe coughing fits occur, often with the characteristic "whoop."
• Convalescent stage: Gradual recovery with decreasing cough severity.

Diagnosis

Diagnosis of Bordetella pertussis infection is typically confirmed through laboratory tests. These may include:

• Polymerase chain reaction (PCR) testing of nasopharyngeal swabs.
• Culture of the bacterium from respiratory specimens.
• Serological tests to detect antibodies against pertussis antigens.

Prevention and Treatment

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Bordetella pertussis under a microscope

Prevention of Bordetella pertussis infection is primarily achieved through vaccination. The DPT vaccine (diphtheria, pertussis, and tetanus) is administered to children to provide immunity against the disease. Booster vaccines are also recommended for adolescents and adults.

Treatment of whooping cough involves the use of antibiotics, such as azithromycin or erythromycin, to reduce the severity and duration of symptoms. Supportive care, including hydration and oxygen therapy, may be necessary in severe cases.

Related Pages

• Whooping cough
• Pertussis toxin
• DPT vaccine
• Bordetella