What bacteria is primarily responsible for erysipelas?

Erysipelas is a superficial skin infection characterized by well-defined, raised borders, often presenting with redness, swelling, and pain. The main causative agent of erysipelas is Streptococcus pyogenes, a bacterium belonging to Group A Streptococcus (GAS). This organism is known for causing various conditions, including pharyngitis, cellulitis, and skin infections like erysipelas.

The pathophysiology involves the invasion of the epidermis and dermis, often following a break in the skin. The immune response leads to the characteristic symptoms and signs associated with this infection, such as fever and systemic symptoms in addition to local redness and swelling.

In contrast, other bacteria mentioned do not typically cause erysipelas. While Staphylococcus aureus can cause skin infections, it is not the primary pathogen associated with this specific condition. Escherichia coli and Listeria monocytogenes have different clinical associations and are less commonly implicated in skin infections like erysipelas, which makes Streptococcus pyogenes the clear answer in this context.