Bordetella pertussis

1. GC 101 (Diagnosis of Infections) — NPA/throat swab specimen rules: "Throat swabs in bacterial transport medium (NOT viral transport medium containing antibiotics) are most important for…Bordetella pertussis." Furthermore, "With the exception of Bordetella pertussis and Neisseria gonorrhoeae, swabs for culture of other pathogens should be refrigerated." This means B. pertussis swabs must be plated immediately — a classic MCQ trap ^[1].

2. GC 101 — PCR as most sensitive test: "Multiplex RT-PCR (most sensitive)" is emphasised across respiratory pathogen diagnosis. For B. pertussis, PCR on nasopharyngeal specimens is the gold standard diagnostic modality ^[1].

3. Felix Lai Paediatrics & Medicine Notes — DTaP-IPV vaccine schedule: "3 doses required at 2nd, 4th and 6th months respectively; Pertussis (aP) = Acellular" ^[2][4]. Know that the "a" in DTaP stands for acellular pertussis — contrasted with older whole-cell vaccines (wP) that had more side effects.

4. Felix Lai Paediatrics Notes — B. pertussis as a cause of bronchiolitis: "Occasionally a bacterial infection such as Mycoplasma pneumoniae or Bordetella pertussis" can cause bronchiolitis in children < 2 years ^[2]. This is a discriminator in a paediatric LRTI vignette — if the child has paroxysmal cough, apnoea, and marked lymphocytosis, think pertussis rather than RSV.

5. Ryan Ho Haematology — Pertussis in the d/dx of reactive lymphocytosis: Listed alongside infectious mononucleosis, HIV, and TB as a cause of reactive lymphocytosis that must be distinguished from ALL ^[3]. In an exam stem showing a child with extremely high WCC and lymphocyte-predominant picture, pertussis should be in the differential before jumping to leukaemia.

• Pertussis vs RSV bronchiolitis: Both present in infants with cough and respiratory distress. Pertussis → paroxysmal cough, inspiratory whoop, post-tussive vomiting, marked lymphocytosis; RSV → wheeze/crackles, seasonal (winter), antigen-detectable on NPA RV panel.
• Pertussis vs Chlamydia trachomatis afebrile pneumonia of infancy: Both cause cough in young infants. C. trachomatis → staccato cough (individual coughs separated by inspiration), age 2-4 months, conjunctivitis, eosinophilia. Pertussis → paroxysmal cough with whoop, lymphocytosis, no conjunctivitis.
• Lymphocytosis trap: Pertussis causes the highest WCC among infectious causes of lymphocytosis (can exceed 100 × 10⁹/L in infants). If a stem shows extreme lymphocytosis in an infant with cough, do NOT default to ALL — check for blasts on PBS.
• Specimen transport trap: B. pertussis is killed by antibiotics in viral transport medium and by cold temperatures — always use bacterial transport medium and plate promptly ^[1].
• Vaccine does not eliminate carriage: Acellular pertussis vaccine prevents severe disease but does not fully prevent nasopharyngeal colonisation or transmission — hence outbreaks can still occur in vaccinated populations.

No directly relevant past paper questions specifically testing Bordetella pertussis were identified in the indexed Fourth Summative past paper stems (2016–2025). The organism appears indirectly in differential diagnosis lists (e.g., reactive lymphocytosis d/dx in haematology contexts ^[3]) but no standalone pertussis-focused MCQ, SAQ, or minicase stem was retrieved from the provided past paper text.