A quantitative model for subcutaneous abscess formation in mice

Area of Science:

• Microbiology
• Immunology
• Pathology

Background:

• Subcutaneous encapsulated abscesses are common infections.
• Developing a reliable experimental model is crucial for studying abscess pathogenesis.
• Quantitative assessment methods are needed for accurate analysis.

Purpose of the Study:

• To establish a reproducible experimental model of subcutaneous encapsulated abscesses.
• To enable quantitative measurements of abscess formation and development.
• To characterize the histological and microbiological features of these abscesses.

Main Methods:

• Subcutaneous inoculation of bacterial (Bacteroides fragilis, Staphylococcus aureus) and/or autoclaved mouse caecal contents into two mouse strains.
• Quantitative assessment of bacterial concentrations in pus.
• Histological analysis and planimetric measurement of abscess components (capsule, neutrophil band, total abscess area).

Main Results:

• Large, encapsulated abscesses formed consistently by Day 4 when inocula contained B. fragilis or S. aureus with caecal contents.
• High bacterial concentrations (10(10.1+/-0.02) for B. fragilis, 10(8.4+/-0.1) for S. aureus) were observed in pus by Day 6.
• Abscesses showed spontaneous drainage by 10-15 days and healed within 4-6 weeks, with reproducible histological features.

Conclusions:

• A reliable experimental model for subcutaneous encapsulated abscesses has been developed.
• The model allows for reproducible quantitative measurements of abscess formation and progression.
• This model can be utilized for further investigations into abscess pathogenesis and therapeutic strategies.