Final answer:
Erysipelas advancing edge usually has a demarcated border.
Step-by-step explanation:
Erysipelas is a type of skin infection caused by bacteria, usually Streptococcus pyogenes. The advancing edge of erysipelas typically has a demarcated border, which means it has a clearly defined boundary separating the affected area from the surrounding healthy skin. This demarcated border can be helpful in diagnosing erysipelas and distinguishing it from other skin infections.