Infectious Diseases
Core concepts
Master congenital and perinatal infections (TORCH and beyond), their timing-dependent effects, and characteristic pathology. Early infection → malformation and growth restriction; late infection → active inflammation and organ damage. Know CMV (periventricular calcifications, inclusion-bearing cells), toxoplasmosis (diffuse calcifications), rubella (cataracts, cardiac defects, deafness), syphilis (osteochondritis, snuffles), and HSV/Zika patterns. Understand group B Streptococcus and E. coli as leading neonatal sepsis pathogens and the role of maternal colonization.
Be able to interpret placental inflammation (chorioamnionitis, villitis) as evidence of ascending vs hematogenous infection. Know the principles of neonatal sepsis evaluation and the limits of cultures.
Traps
Questions exploit calcification patterns (periventricular = CMV; diffuse = toxo) and timing (first trimester rubella vs later infection). Another trap: assuming all villitis is infectious-some is immune-mediated. Do not confuse ascending infection (membranes, cord) with hematogenous (villous) infection.
Worked example / rule of thumb
A growth-restricted infant with periventricular calcifications, hearing loss, and inclusion-bearing cells: CMV. Rule of thumb: "Ascending → membranes and cord; hematogenous → villi and fetus."