Streptococci are the bacteria that can cause a strep throat disease. It is classified as a contagious disease that is caused by an infection with the streptococcal bacteria. When this bacteria infects the area of throat, swelling and inflammation of the mucous membranes lining of the throat and tonsils occur. This disease is common for school-aged children and teens. Upon the diagnosis of the disease, medications (e.g. antibiotics) should be given to prevent further potential complications of the disease.