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Severe Dermatitis Associated with Spontaneous Staphylococcus xylosus Infection in Rag Mice
Nicole V Acuff1, Monica LaGatta1, Tamas Nagy2
1Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA.
Abstract:
Staphylococcus xylosus is a commensal bacterium found on the skin and mucosal surfaces of SPF mice. S. xylosus is rarely pathogenic, most often causing skin lesions and dermatitis in immunocompromised mice, particularly those with impaired NADPH oxidase function. Here we report spontaneous infection with S. xylosus in Rag1-/-Tpl2-/- mice. Infection was characterized by the presence of alopecia, crusts, and scaly skin. S. xylosus was detected in the feces, skin, lymph nodes, and lungs of Rag1-/-Tpl2-/- mice and led to mortality or euthanasia due to humane endpoints. C57BL/6 mice were culture-positive for S. xylosus on the skin, and Rag1-/- and Tpl2-/- mice were culture-positive on the skin and occasionally in the feces. However, S. xylosus did not cause clinical symptoms in C57BL/6, Rag1-/-, or Tpl2-/- mice. Compared with those in Rag1-/- mice, relative concentrations of circulating monocytes, but not neutrophils or lymphocytes, were increased in Rag1-/-Tpl2-/- mice, consistent with their increased incidence of clinical symptoms. Overall, this case study suggests a novel role for Tpl2 in T-cell-independent host resistance to the otherwise commensal organism S. xylosus.
Insights
A spontaneous Staphylococcus xylosus infection caused severe symptoms and mortality in Rag1-/-Tpl2-/- mice. This study highlights Tpl2
Area of Science:
- Immunology
- Microbiology
- Genetics
Background:
- Staphylococcus xylosus is a common skin commensal in mice.
- It rarely causes disease, typically in immunocompromised individuals with NADPH oxidase defects.
- Previous studies have not detailed S. xylosus infections in specific knockout mouse models.
Purpose of the Study:
- To investigate a spontaneous Staphylococcus xylosus infection in Rag1-/-Tpl2-/- mice.
- To characterize the clinical presentation and pathology of this infection.
- To explore the role of Tpl2 in host resistance to S. xylosus.
Main Methods:
- Observation of spontaneous S. xylosus infection in Rag1-/-Tpl2-/- mice.
- Clinical assessment including alopecia, crusts, and scaly skin.
- Bacterial culture from various tissues (skin, feces, lymph nodes, lungs).
- Hematological analysis comparing monocyte, neutrophil, and lymphocyte counts.
Main Results:
- Rag1-/-Tpl2-/- mice developed severe clinical signs including alopecia, crusts, and scaly skin.
- S. xylosus was disseminated in Rag1-/-Tpl2-/- mice, leading to mortality.
- Increased circulating monocytes were observed in Rag1-/-Tpl2-/- mice compared to Rag1-/- mice.
- C57BL/6, Rag1-/-, and Tpl2-/- mice showed no clinical symptoms despite S. xylosus colonization.
Conclusions:
- Tpl2 plays a role in host resistance against Staphylococcus xylosus.
- T-cell-independent mechanisms mediated by Tpl2 may be crucial for controlling this commensal bacterium.
- This case study suggests a novel function for Tpl2 in managing S. xylosus infections.
