This bacteria is a facultative anaerobe that is gram-positive and is approximately 2 micrometers long. S. salivarius occurs in pairs and short chains. This organism is primarily an aerobe but it can perform anaerobic respiration as well. Usually, it inhabits the area between the obligate anaerobes and the aerobes, where oxygen is available but sometimes limited. This organism is only known to infect the upper-respiratory tract of humans, but on some rare occasions it can be spread to the circulatory system through abrasions on the gum. It is found worldwide and is associated with dental carries, as it can produce lactic acid through anaerobic respiration. The host range of S. salivarius is limited to humans. It is susceptible to the antibiotics penicillin and erythromycin. It can be rendered physically inactive at 121 degrees Celsius of moist heat or 160-170 degrees Celsius in dry heat. The optimal temperature for S. salivarus is body temperature 37 degrees Celsius.