What describes a contagious bacterial skin infection with pustules and crusty sores?

The correct answer is impetigo, which is a highly contagious bacterial skin infection commonly occurring in children. It is characterized by the formation of pustules or blisters that are filled with fluid, which eventually break open, leading to the development of crusty sores on the skin. This condition is often caused by bacteria such as Staphylococcus aureus or Streptococcus pyogenes.

Impetigo typically appears around the face, mouth, and nose but can occur anywhere on the body. The crusting and the presence of pus make it visually distinctive and easily recognizable. Quick treatment is important to prevent the spread of the infection to others and to help the sores heal more rapidly.

In contrast, MRSA (Methicillin-Resistant Staphylococcus Aureus) refers to a type of bacteria resistant to many antibiotics and can also cause skin infections, but it is not specifically characterized by pustules and crusty sores like impetigo is. Lacerations and abrasions, while they are skin injuries, do not describe infectious conditions and instead refer to cuts or scrapes on the skin. Therefore, impetigo is the most appropriate description for the contagious bacterial skin infection mentioned in the question.