ABSTRACT
Objective To establish a stable animal model for sequentially dynamic and direct monitoring of the skin wound infection. Methods The mice with full-thickness skin incisions were replicated. After immediate subcutaneous suture,the mice were randomly divided into four groups,ie,Group A was inoculated with 50 μl sterile PBS solution),Groups B,C and D were inoculated with 50 μl suspension containing 1 × 106,1 × 108 and 1 × 1010 colony forming unit (CFU)/ml bioluminescent methicillin-resistant staphylococcus aureus (MRSA) respectively.Then,the diet behavior of each group was observed and the mean weight and mortality of each group were also recorded at different time points.The bioluminescent intensity of fluoresce in the wounds was recorded at different time points by using the charge-coupled device (CCD) based imaging system.Local wound tissues were incised at 24 hours after inoculation for HE staining so as to observe wound inflammatory reaction in each group.Wound healing time of each group was also recorded. Results ( 1 ) Average weight:Groups A and B showed unobvious changes in weight; Group C lightened until day 3 after inoculation and then recovered gradually to the preinoculation level at day 14; Group D lightened gradually until death.(2)Mortality:Groups A and B had no death; Group C had 10％ deaths at day 14; Group D had 100％ deaths.(3) Bioluminescent intensity of wounds:Groups A and B showed a gradual weakened luminescence since the day of inoculation and had almost complete disappearance at days 5 and 7 respectively; there was no sign of obvious increase or decrease in Group C from the day of inoculation till day 14 ; Group D had a gradual increase since the day of inoculation and the luminous area expanded until the death.(4) HE staining at 24 hours after inoculation:all the four groups showed inflammatory cell infiltration,especially in Groups C and D.(5) Wound healing time:wound healed at days 5 and 7 after inoculation in Groups A and B; the wounds showed no healing even at day 14 in the Group C,but the wounds length and area did not show obvious enlargement or diminishment ; the wounds extended gradually until the death in the Group D,since the day of inoculation. Conclusions The inoculation of 50 μl suspension with 1 × 108 CFU/ml bioluminescent MRSA to full-thickness skin incision rats allows direct,real-time dynamic and continuous detection of the occurrence and development of the wound infections.The infection model is easy to make and has stability and high repeatability.