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Contamination of wounds with fecal bacteria in immuno-suppressed mice
Lisa Karner1, Susanne Drechsler1, Magdalena Metzger1
1Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Donaueschingenstraße 13, 1200, Vienna, Austria.
Abstract:
Immunocompromised patients are predisposed to chronically infected wounds. Especially ulcers in the dorsal region often experience secondary polymicrobial infections. However, current wound infection models mostly use single-strain bacteria. To mimic clinically occurring infections caused by fecal contamination in immunocompromised/immobile patients, which differ significantly from single-strain infections, the present study aimed at the establishment of a new mouse model using infection by fecal bacteria. Dorsal circular excision wounds in immunosuppressed mice were infected with fecal slurry solution in several dilutions up to 1:8,000. Impact of immunosuppressor, bacterial load and timing on development of wound infections was investigated. Wounds were analyzed by scoring, 3D imaging and swab analyses. Autofluorescence imaging was not successful. Dose-finding of cyclophosphamide-induced immunosuppression was necessary for establishment of bacterial wound infections. Infection with fecal slurry diluted 1:166 to 1:400 induced significantly delayed wound healing (p < 0.05) without systemic reactions. Swab analyses post-infection matched the initial polymicrobial suspension. The customized wound score confirmed significant differences between the groups (p < 0.05). Here we report the establishment of a simple, new mouse model for clinically occurring wound infections by fecal bacteria and the evaluation of appropriate wound analysis methods. In the future, this model will provide a suitable tool for the investigation of complex microbiological interactions and evaluation of new therapeutic approaches.
Insights
This study developed a new mouse model for chronic wound infections using fecal bacteria in immunocompromised mice. This model accurately mimics polymicrobial infections, aiding future therapeutic research.
Area of Science:
- Microbiology
- Immunology
- Wound Healing Research
Background:
- Immunocompromised patients frequently develop chronic, polymicrobial wound infections, particularly in dorsal ulcer regions.
- Existing animal models often utilize single bacterial strains, failing to replicate complex, polymicrobial infections seen in clinical settings.
- Fecal contamination is a common cause of infection in immobile or immunocompromised patients, necessitating a more relevant model.
Purpose of the Study:
- To establish and validate a novel mouse model for simulating polymicrobial wound infections using fecal bacteria.
- To investigate the influence of immunosuppression, bacterial load, and infection timing on wound development.
- To evaluate suitable methods for analyzing wound infections within this new model.
Main Methods:
- Dorsal circular excision wounds were created in immunosuppressed mice (cyclophosphamide-induced).
- Wounds were infected with varying dilutions of fecal slurry (up to 1:8,000).
- Wound healing was assessed using scoring, 3D imaging, and swab analyses; autofluorescence imaging was explored but unsuccessful.
Main Results:
- Dose-finding for cyclophosphamide was crucial for establishing infections.
- Fecal slurry dilutions of 1:166 to 1:400 significantly delayed wound healing (p < 0.05) without systemic effects.
- Swab analyses confirmed the presence of the initial polymicrobial fecal suspension in the wounds.
- A customized wound score effectively differentiated between experimental groups (p < 0.05).
Conclusions:
- A simple, effective mouse model for studying clinically relevant, fecal-driven polymicrobial wound infections has been successfully established.
- This model allows for the investigation of complex microbial interactions and the assessment of novel therapeutic strategies.
- The model provides a valuable tool for advancing research in chronic wound infections.
