Pediatric Infectious Diseases and Immunology
Domain focus
Pediatric Infectious Diseases and Immunology tests age-specific fever evaluation, vaccine-preventable illness, antimicrobial choice and primary immunodeficiency red flags. Fever in infancy is a high-yield area.
Core rules
- A febrile infant under 3 months needs careful evaluation: temperature, urine, blood and, when indicated, cerebrospinal fluid cultures; treat ill-appearing infants empirically.
- In older children, focus on source, toxicity and risk factors rather than fever height alone.
- Use narrow antibiotics when possible and adjust to weight and renal function.
- Immunodeficiency red flags: recurrent severe or unusual infections, failure to thrive, family history, complications after live vaccines, or persistent lymphopenia.
- BCG protects against severe disseminated tuberculosis in children, not against pulmonary TB.
Worked example
A 6-week-old has temperature 38.4°C, poor feeding and lethargy. Obtain full sepsis evaluation including urine by catheter and CSF, give IV ampicillin plus gentamicin, and add acyclovir if vesicles, seizures or CSF pleocytosis suggest neonatal herpes. Admit and reassess cultures at 36–48 hours. Do not send the infant home solely because the examination is initially reassuring.
Traps
Missing meningitis because the fontanelle is flat; using oral amoxicillin for a toxic infant; ignoring asplenia prophylaxis; misreading BCG scarring as immunity to all TB; failing to adjust drug doses.