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The Difference in Virulence between Clinically Recovered Staphylococcus Aureus and an Established Strain Applied to a Skin Ulcer Model
Author(s) -
Masahiro Tachi,
Shinichi Hirabayashi
Publication year - 2004
Publication title -
wound repair and regeneration
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.847
H-Index - 109
eISSN - 1524-475X
pISSN - 1067-1927
DOI - 10.1111/j.1067-1927.2004.abstractbg.x
Subject(s) - staphylococcus aureus , gram staining , strain (injury) , microbiology and biotechnology , granulation tissue , medicine , staining , virulence , staphylococcus , stain , wound healing , bacteria , surgery , pathology , biology , antibiotics , anatomy , gene , biochemistry , genetics
Aim: We attempted to establish a rat model by placing gauze on a wound bed. We then used this model to evaluate the virulence of an established strain of Staphylococcus Aureus and a clinical strain isolated from a patient with a wound infection. Methods: Using a 1.5 × 1.5 cm template, full thickness skin wounds were made through the panniculus carnosus on the backs of rats. A small piece of gauze was placed over each wound. The wound beds were inoculated with 1.5 × 10 6 cfu of Staphylococcus Aureus from the American Type Culture Collection, or 1.5 × 10 6 cfu of a clinical isolate. The wounds were debrided every 48 hours and samples taken to the laboratory for quantitative bacteriologic analysis. Specimens were fixed and stained by H/E and Gram staining. Results: The clinical strain of Staphylococcus Aureus resulted in bacterial counts (cfu per gram of tissue) exceeding 10 7 on days 2 to 6, while the established stain produced bacterial counts exceeding 10 7 cfu on days 2 to 4 only. Gram stain analysis revealed that the clinical strain penetrated deep granulation tissue, whereas, the established strain was present in small cell nests at the wound margins. Conclusion: A clinical strain isolated from a patient showed deeper penetration of the wound bed than an established strain, resulting in prolonged elevation of the bacterial count.