Animals Anti-Bacterial Agents--therapeutic use Anti-Inflammatory Agents--therapeutic use Cefaclor--therapeutic use Clarithromycin--therapeutic use Dermatitis, Atopic--complications Dexamethasone--therapeutic use Histocompatibility Antigens Class II--metabolism Immunosuppressive Agents--therapeutic use Male Mast Cells--immunology Mice Mice, Inbred Strains Skin--immunology Staphylococcal Skin Infections--complications Staphylococcus aureus Time Factors