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Furuncle-like lesions in mouse experimental skin infections with Staphylococcus aureus
Abstract:
The pathomechanism of furuncle has not been fully elucidated and should be investigated using an appropriate animal model. We observed the invasion of Staphylococcus aureus cells into hair follicles in mice, using a strain of S. aureus isolated from human furunculosis. Light microscopical examination revealed that S. aureus cells attached to corneocytes at 6 h after inoculation, proliferated around the ostium of the hair follicle and invaded the hair follicle at 12 h after inoculation. Electron microscopically, S. aureus cells attached to the horny layer of hair follicle with long, thick, string-like structures. At 12 h after inoculation, S. aureus cells invaded in a file between the inner root sheath and outer root sheath. We could not induce direct invasion from the follicle ostium. Our findings suggest that there are some regions of the hair follicle through which S. aureus cells can relatively easily invade deeper into the follicle. The most important question is what confines the invasion and inflammation of S. aureus to the hair follicle. We suggest that there is some locus minoris for invasion into hair follicles by S. aureus, such as an interface between the two sheaths.
Insights
Staphylococcus aureus invades hair follicles through specific regions, not directly from the opening. This study identifies potential invasion points for furuncle development.
Area of Science:
- Microbiology
- Dermatology
- Pathology
Background:
- The precise mechanisms driving furuncle pathogenesis remain incompletely understood.
- Investigating furuncle development requires a suitable animal model to elucidate pathomechanisms.
Purpose of the Study:
- To investigate the pathomechanism of furuncle development using an animal model.
- To observe the invasion process of Staphylococcus aureus into hair follicles.
Main Methods:
- Utilized a mouse model inoculated with Staphylococcus aureus isolated from human furunculosis.
- Employed light and electron microscopy to examine bacterial invasion at 6 and 12 hours post-inoculation.
- Focused on bacterial attachment, proliferation, and invasion pathways within the hair follicle structure.
Main Results:
- Staphylococcus aureus attached to corneocytes within 6 hours and proliferated around the hair follicle ostium.
- Bacterial invasion into the hair follicle occurred by 12 hours, with cells forming string-like structures on the horny layer.
- Invasion was observed between the inner and outer root sheaths; direct invasion from the ostium was not induced.
Conclusions:
- Staphylococcus aureus invades hair follicles via specific, less resistant regions, rather than directly through the ostium.
- The interface between the inner and outer root sheaths is suggested as a potential locus minoris for bacterial invasion.
- Further research is needed to understand factors limiting invasion and inflammation to the hair follicle.