Therapeutic Activity of Lysostaphin in Experimental Staphylococcal Infections

When tested in three experimental staphylococcal infections—acute peritonitis in mice, mouse leg edema produced by a localized infection, and dermal rabbit ear infections—lysostaphin demonstrated in vivo chemotherapeutic activity. Doses of less than 0.007 mg/kg (intraperitoneally) and 0.5 mg/kg (subcutaneously) of lysostaphin prevented death in 50% of the mice with acute staphylococcal peritonitis. A single intramuscular dose (0.15 mg/mouse) of lysostaphin suppressed the swelling produced by the injection of staphylococci into mouse legs to 50% of that produced in untreated animals. Lysostaphin (0.05% by weight) incorporated into gels and applied topically eradicated staphylococci from experimental skin lesions on the ears of rabbits. Lysostaphin was absorbed and transported by the body fluids from the point of injection to the site of the infection producing a desirable antistaphylococcal effect.