Which organism causes pertussis (whooping cough)?

Which organism causes pertussis (whooping cough)?

• A. Streptococcus pneumoniae
• B. Mycoplasma pneumoniae
• C. Haemophilus influenzae
• D. Bordetella pertussis

Answer: (D)

Pertussis is caused by Bordetella pertussis, a small gram-negative coccobacillus that adheres to the ciliated cells of the respiratory tract and releases toxins that disrupt normal mucociliary clearance. This toxin-mediated damage leads to the hallmark paroxysmal coughing spells and the characteristic "whoop" sound, especially in unvaccinated or young children. The illness typically progresses through stages: an initial catarrhal stage with mild, flu-like symptoms, followed by the paroxysmal stage of severe coughing fits, and then a recovery/convalescent phase as symptoms wane. Transmission occurs through respiratory droplets, which is why vaccination is crucial. The standard preventive measure is the DTaP vaccine in childhood with a Tdap booster later in life to maintain protection. If diagnosed early, macrolide antibiotics can reduce the duration of symptoms and especially help prevent spread to others. The other organisms listed are associated with different respiratory infections: Streptococcus pneumoniae commonly causes pneumococcal pneumonia and meningitis; Mycoplasma pneumoniae causes an atypical form of pneumonia; Haemophilus influenzae can cause epiglottitis, otitis media, and sinusitis. None of these produce the classic pertussis toxin–driven illness with the distinctive whooping cough.

Pertussis is caused by Bordetella pertussis, a small gram-negative coccobacillus that adheres to the ciliated cells of the respiratory tract and releases toxins that disrupt normal mucociliary clearance. This toxin-mediated damage leads to the hallmark paroxysmal coughing spells and the characteristic "whoop" sound, especially in unvaccinated or young children. The illness typically progresses through stages: an initial catarrhal stage with mild, flu-like symptoms, followed by the paroxysmal stage of severe coughing fits, and then a recovery/convalescent phase as symptoms wane.

Transmission occurs through respiratory droplets, which is why vaccination is crucial. The standard preventive measure is the DTaP vaccine in childhood with a Tdap booster later in life to maintain protection. If diagnosed early, macrolide antibiotics can reduce the duration of symptoms and especially help prevent spread to others.

The other organisms listed are associated with different respiratory infections: Streptococcus pneumoniae commonly causes pneumococcal pneumonia and meningitis; Mycoplasma pneumoniae causes an atypical form of pneumonia; Haemophilus influenzae can cause epiglottitis, otitis media, and sinusitis. None of these produce the classic pertussis toxin–driven illness with the distinctive whooping cough.