Murine model of cutaneous infection with gram-positive cocci.

Abstract

Staphylococcus aureus has remained an important cause of nosocomial wound infections, but standardized or reproducible systems for analyzing cutaneous infections caused by S. aureus do not exist. A variety of foreign materials, variable inocula, and skin traumas have been used to promote infection. To minimize these variables and ensure reproducibility, we chose a model using subcutaneous injections of a fixed quantity of dextran microbeads (Cytodex) as the foreign material added to standardized broth suspensions of S. aureus. Suspensions (0.2 ml) injected into an outbred strain of immunocompetent hairless mice generated reproducible, measurable lesions. With S. aureus Smith Diffuse, fluctuant, erythematous lesions with a peak diameter of 15 mm were observed; these lesions yielded purulent material containing gram-positive cocci and neutrophils and yielded growth of S. aureus on culture. Lesion size was proportional to the bacterial inoculum size. Histologic examination of excised lesions revealed typical abscesses. A second strain of S. aureus (SLC3) produced dermonecrosis instead of abscesses at an inoculum size of 10(7) CFU. Control injections with a sterile Cytodex suspension regularly produced nondraining, nonerythematous nodules with maximum diameters of less than or equal to 5 mm. Streptococcus pyogenes produced late-onset necrotic lesions and abscesses. Using a foreign substance, this model generates easily observed and reproducible cutaneous infection with S. aureus and streptococci that can potentially discriminate between inter- and intrastrain differences. Such a model could be used to test the pathogenicity of isogeneic strains of these bacterial species and to evaluate the efficacy of antimicrobial agents.

• Authors: C Bunce, L Wheeler, G Reed, J Musser, N Barg
• Journal: Infection and immunity (Infect Immun) Vol. 60 Issue 7 Pg. 2636-40 (Jul 1992) ISSN: 0019-9567 [Print] United States
• PMID: 1612733 (Publication Type: Comparative Study, Journal Article)

Topics

• Analysis of Variance
• Animals
• Disease Models, Animal
• Male
• Mice
• Skin Diseases, Infectious (pathology)
• Staphylococcal Skin Infections (pathology)
• Staphylococcus aureus
• Streptococcal Infections
• Streptococcus pyogenes (pathogenicity)