Infectious Disease Emergencies
This domain emphasizes recognition of time-critical infections and age-appropriate evaluation of fever. Candidates must understand the febrile infant workup stratified by age, the approach to sepsis (early recognition, cultures, antibiotics within the appropriate window), and the red flags of meningitis, including nuchal rigidity, altered mental status, and petechial rash. Know that young infants may present with nonspecific signs and that group B streptococcus and Escherichia coli are important neonatal pathogens.
Key concepts include the distinction between bacterial and viral syndromes, the role of vaccination status, and the recognition of toxic appearance as a trigger for aggressive evaluation. Understand empiric antibiotic selection principles and the importance of source control.
Traps: attributing a petechial rash to a benign cause without considering meningococcemia; delaying antibiotics for lumbar puncture in an unstable child; and missing that a well-appearing febrile infant younger than a threshold age still requires evaluation. Another trap is over-reliance on a single normal laboratory value.
Worked example: a toddler with fever, lethargy, and a rapidly spreading petechial rash should receive immediate resuscitation and empiric antibiotics targeting meningococcal disease, with lumbar puncture deferred if the child is unstable. Rule of thumb: a toxic-appearing child gets resuscitation and antibiotics before complete diagnostics, and age determines the fever workup threshold.