Staphylococcus aureus, or staph, is a bacteria that is commonly found in the nose and on the skin of humans. While it is typically not harmful to humans, it is sometimes able to enter the body through an injury or broken skin, and get into the bloodstream. When this happens, it can cause a serious infection called sepsis. Sepsis can cause an individual to go into shock and bodily organs to stop functioning. Symptoms of sepsis include inflammation, fever or hypothermia, increased heart rate, and rapid breathing. A microscopic image of staphylococcus aureus is shown.

Which immune system component initially results in the inflammation and responds quickly when Staphylococcus aureus enters the bloodstream?
complement system
phagocytes
Langerhans cells
B lymphocytes