Septic infection is a type of infection of the skin caused by septic bacteria that can occur in any location. If folliculitis is left untreated and causes a septic infection, large nodules, pus, and pain may occur. Other skin wounds, such as mosquito bites or surgical wounds, or other trauma-induced skin breaks, may also become red, runny, painful, or may even cause fever or systemic infection if they are infected with septic bacteria.