STAPHYLOCOCCUS-AUREUS INFECTION ON CUT WOUNDS IN THE MOUSE SKIN - EXPERIMENTAL STAPHYLOCOCCAL BOTRYOMYCOSIS

Staphylococcus aureus cells were inoculated on the cut wounds in the s kin of cyclophosphamide-treated mice. Biopsy specimens were taken from three mice at 1, 3, 6, 12, 24, 36, 48 and 60 h after the inoculation and were examined by light and electron microscopies. One hour after t he inoculation Staphylococcus aureus cells were seen around the cut wo und and deeper into the subcutaneous tissue. By 6 h after the inoculat ion, Staphylococcus aureus cells formed clusters of bacterial colonies . By 36 h after the inoculation inflammatory cells, mainly polymorphon uclear leukocytes and macrophages, were seen around the clusters. Elec tron microscopic examination revealed fibril-like structures around th e Staphylococcus aureus cells at 1 h. The Staphylococcus aureus cells were enclosed in membrane-like structures at 3 h. The membrane-like st ructures and the fibril-like structures were positive for Ruthenium re d. By 12 h after the inoculation, the membrane-like structures increas ed in thickness; and in electron density. Inflammatory cells were seen around but outside of the membrane-like structures at 24, 36 and 48 h . At 60 h the tissues around the membrane-like structures were degener ated and almost necrotic. These results suggest that Staphylococcus au reus cells may form biofilm in dermal or subcutaneous tissues in a neu tropenic condition.