Low dose of protein A pretreatment can alleviate the inflammatory reaction and the bio-safety was evaluated in vivo.

BACKGROUND Staphylococcal protein A (SPA) is a protein of Staphylococcus aureus. Up to now, there have been many studies on the biological activities of SPA. Some reported effects of SPA pretreatment on septic shock in mouse models but there is no study which reports the role of SPA pretreatment on the infected incision. METHODS According to count results, bacterial suspension was set at a density of ∼1.8 × 10(9) colony forming units/mL. BALB/c mice were anesthetized via intraperitoneal injection with pentobarbital sodium. A longitudinal skin incision was made on the medial side of the right thigh. The length of the incision was 5 mm, and the depth was ∼3 mm. The bacterial suspension was gradually dripped and embrocated onto the incision surface to make the wound infection model. Before making the wound infection model for 48 hours and 24 hours, mice were retreated with SPA via intraperitoneal injection. Rats were intraperitoneally injected with SPA 1 mg/kg and the control group was injected with sterile saline to evaluate the biological safety of the best pretreatment dose. RESULTS A 1-mL bacterial suspension can be utilized to make the wound infection model of BALB/c mouse lower limb. SPA pretreatment can reduce the inflammatory reactions in wound methicillin-resistant Staphylococcus aureus infection mouse model and the best pretreatment dose is 1 mg/kg. Intraperitoneal injection 1 mg/kg SPA does not destroy the functions of the organs. A 1-mg/kg SPA pretreatment can also reduce the inflammatory reactions in wound various bacterial infection mouse models. CONCLUSION SPA pretreatment can effectively decrease the infected severity of a wound infected by various bacteria in a BALB/c mouse model. The best pretreatment dose is 1 mg/kg, and this dose does not damage organ function in rats up to a point.