Sepsis: bacterial embolus of purulent focus intermittently enters the blood circulation and is brought to other parts of the body, resulting in metastatic abscess.
Toxicology: In the infected part, a large number of toxins and decomposition products of tissue destruction produced by pathogenic bacteria enter the blood circulation, causing systemic poisoning reaction, but pathogenic bacteria do not invade the blood circulation.
Bacteremia: A small amount of pathogenic bacteria invade the blood circulation and are quickly eliminated by the human defense system, causing no or only a slight and short-term systemic reaction.