There are two types of strep bacteria that can cause strep skin infections. Group A strep is the most common cause. Group B is the other cause.
Group A strep (GAS)
Group A strep (GAS) can cause a wide range of skin infections. Examples are impetigo, cellulitis, erysipelas, and necrotizing fasciitis. It can also cause infections in the upper respiratory tract.
GAS is contagious and can be spread through respiratory droplets. It can also be spread through contact with infected skin, sores, saliva, and nasal discharge.
Group B strep (GBS)
Group B strep (GBS) is commonly found in the gastrointestinal and genital tracts. It is usually harmless. But it can cause skin and soft tissue infections.