Pimple-like sores on the legs are most commonly minor skin infections, according to TeensHealth. Staphylococcus and streptococcal bacteria are two of the most prevalent types of bacteria to infect the skin, and both create sores that fill with pus before popping. Both of these types of bacteria are found on the body and in the environment, and they typically enter through a small break on the skin's surface.
Staphylococcus bacteria, or staph, can be found around the nose, mouth, genitals and anus, according to TeensHealth. Most staph skin infections are minor and can be spread through skin-to-skin contact or skin contact with a contaminated object. Warm and humid environments contribute to the growth of the staph bacteria, making it prevalent in locker rooms and gyms. A staph infection can become serious if it moves into the bloodstream or other parts of the body, or when the bacteria causing the infection is resistant to some types of antibiotics. Staph infections are treated using topical and oral antibiotics.
Group A streptococcal bacteria, or strep, can also cause a pimple-like outbreak on the skin, according to the Cleveland Clinic. Spread in the same way as staph bacteria, strep bacteria that causes skin infections is slightly different than the strep bacteria that causes a sore throat. Strep infections are treated using both oral and topical antibiotics.