Establishment of a simple superficial skin infection model in mice and verification of its effectiveness

The aim of this study is to establish a mouse model close to clinical simple superficial skin infection for the study of screening and therapeutic effect of topical antimicrobial agents as well as the pathogenic mechanisms. The skin barrier of BALB/c mice was disrupted with partial removal of the epidermal layer by tape stripping the topical skin in succession and TEWL values were measured to standardize the degree of barrier disruption. The topical skin was infected by Staphylococcus aureus pathogens(7. 5×10⁶ CFU/mL)or Streptococcus pyogenes(1. 5×10⁸ CFU/mL)after disruption of skin barrier. The sensitivity and effectiveness of superficial skin infection model was verified by treatment of skin lesions with ofloxacin gel. The results showed that tape- stripping 7 and 10 times respectively were optimal methods of destruction of skin barrier for superficial skin infection of Staphylococcus aureus and Streptococcus pyogenes. The CFU numbers recovered from the skin wound after application of 6 strains of Staphylococcus aureus and 3 strains of Streptococcus pyogenes were 4. 99±4. 74, 5. 52±5. 45, 4. 92±4. 56, 5. 24±4. 84, 5. 20±5. 01, 4. 94±4. 69, and 4. 82±4. 87, 5. 34±5. 45, 4. 63±4. 41 CFU/g, respectively. There is significant difference between the control groups and the model groups(P< 0. 01). The inhibition rates of bacterial growth in skin lesion after ofloxacin gel treatments were more than 80%. The results suggest that the established superficial skin infection model is sensitive and effective. It should be applicable to study the pathogenesis and evaluation of novel topical antimicrobial treatments of superficial skin infections caused by Staphylococcus aureus and Streptococcus pyogenes.