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Ear tag induced Staphylococcus infection in mice
C E Cover1, C M Keenan, G E Bettinger
1Haskell Laboratory for Toxicology and Industrial Medicine, E.I. du Pont de Nemours and Company, Newark, DE 19714.
Laboratory Animals
|July 1, 1989
Summary
A 2-year oral toxicity study in mice revealed Staphylococcus aureus infection linked to ear tag insertion sites. This led to moist dermatitis, organ necrosis, and systemic illness, highlighting infection risks from animal identification methods.
Area of Science:
- Veterinary Pathology
- Microbiology
- Toxicology
Background:
- Animal identification methods, such as ear tags, are common in research settings.
- Staphylococcus aureus is a known skin commensal in laboratory mice.
- Wound contamination can lead to systemic bacterial infections.
Purpose of the Study:
- To investigate the cause of progressive dermatitis and systemic illness in mice during a 2-year oral toxicity study.
- To identify the etiological agent responsible for observed clinical and pathological findings.
Main Methods:
- Mice underwent a 2-year oral toxicity study.
- Clinical signs, gross necropsy findings, and histological changes were documented.
- Bacteriological cultures were performed on skin, kidneys, and heart blood.
Main Results:
- Mice developed progressive, moist dermatitis originating at metal ear tag sites.
- Clinical signs included pruritus, weight loss, rough coat, and morbidity.
- Necropsy revealed pale, granular kidneys; histology showed inflammation and necrosis in visceral organs and skin.
- Staphylococcus aureus was the predominant organism isolated from skin, kidneys, and blood.
Conclusions:
- The insertion of metal ear tags created wounds that served as the portal of entry for Staphylococcus aureus.
- Staphylococcus aureus infection led to dermatitis, visceral organ necrosis, and systemic illness in the study mice.
- This study underscores the potential for complications arising from animal identification procedures in research settings.