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The natural history of murine intra-abdominal abscess formation
W G Cheadle1, M J Hershman, J D Pietsch
1Price Institute of Surgical Research, Department of Surgery, University of Louisville, School of Medicine, KY 40292.
Abstract:
We determined the natural history of experimental abscess formation and had a secondary interest in the effect of muramyl dipeptide. Swiss-Webster mice were injected intraperitoneally with autoclaved mouse fecal suspension and either Bacteroides fragilis (10(8) colony-forming units [cfu]/mL) alone or Escherichia coli (10(4) cfu/mL), enterococcus (10(3) cfu/mL), and B fragilis (10(5) cfu/mL) after pretreatment with muramyl dipeptide or saline solution. All deaths occurred within 48 hours of injection and surviving mice, including those bearing abscesses, appeared to be healthy throughout the study. The number of mice with abscesses and the number of abscesses per group were at their maximum at two to four weeks. Groups with live bacteria had a substantial reduction in the number of abscesses between eight and 26 weeks, compared with two- and four-week values. Manual rupture of palpably large eight-week-old abscesses in 21 mice produced only one death and at autopsy two weeks later, all of the mice showed multiple smaller abscesses. Abscess formation appeared to be beneficial and the natural history of such may include spontaneous resolution without mortality.
Insights
Muramyl dipeptide did not alter abscess formation in mice. Abscesses naturally resolved over time, suggesting spontaneous resolution is a key part of abscess natural history.
Area of Science:
- Microbiology
- Immunology
- Pathology
Background:
- Abscesses are localized collections of pus, often caused by bacterial infections.
- Understanding the natural progression of abscesses is crucial for developing effective treatment strategies.
Purpose of the Study:
- To determine the natural history of experimental abscess formation in mice.
- To investigate the effect of muramyl dipeptide on abscess development and resolution.
Main Methods:
- Swiss-Webster mice were injected with bacterial suspensions (Bacteroides fragilis, Escherichia coli, enterococcus) to induce abscesses.
- Mice were pretreated with either muramyl dipeptide or saline solution.
- Abscess formation, size, and resolution were monitored over 26 weeks.
Main Results:
- Abscess formation peaked at two to four weeks post-injection.
- Groups receiving live bacteria showed a significant reduction in abscesses between eight and 26 weeks.
- Manual rupture of large abscesses led to smaller, multiple abscesses, with low mortality.
- Muramyl dipeptide did not significantly alter abscess formation or resolution.
Conclusions:
- Experimental abscesses in mice exhibit a natural history characterized by initial formation followed by spontaneous resolution.
- Abscess resolution can occur without mortality, indicating a potentially beneficial role in the host's response.
- Muramyl dipeptide does not appear to influence the natural course of abscess formation or resolution in this model.