This is the result of injecting the T-Virus into salamanders, and tampering with their DNA. They have an incredible growth rate, and can generate a large electric field several times more powerful than the animal it was based off. This is an infant, and does not possess this power until its fully grown.
Whilst in the Biohazard Containment Room, you see several of these little creature break free and scuttle around. It's best to just avoid these, as they have the ability to shock you but its not very damaging. One manages to escape the room, however, you never encounter it again in this form.