Streptokinase actually indirectly breaks down blood clots via the activation of another enzyme known as plasminogen which ultimately cleaves into plasmin which is the "action taker" in breaking down clots. Since streptokinase is only an enzyme and not a weaken pathogen such as vaccines, streptococcus won't invade the host.Fibrinolytic produces plamin. IV administered for heart attack dissolves clots in walls of arteries. Enzymes don't cause disease. Virus or infection cause disease. Enzymes are specific, doesn't eat everything.