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Characterization of pig skin microbiome and appraisal as an in vivo subcutaneous injection model
Sofia Wareham-Mathiassen1,2, Vera Pinto Glenting3, Lene Bay1
1Department of Immunology and Microbiology, Copenhagen University, Denmark.
Abstract:
Pig skin is commonly used in the medical industry as an injection model due to its compelling physiological affinity to human skin. However, the pig neck skin microflora remains largely uncharacterized, which may have undesirable implications for the translatability of results to humans. This study aimed to characterize pig neck skin microbiome with direct comparison with human skin microflora at emblematic injection sites to appraise its suitability as an injection model. Ten minipigs were sampled with tape strips and swabs and analysed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry and 16S/ITS high throughput sequencing and confocal laser scanning microscopy. Results were directly compared with previous investigations of human injection sites. Pig skin was dominated by phyla 94.8% Firmicutes, 3% Proteobacteria, and 2.2% Actinobacteria. Staphylococcus spp. prevailed (44.4%) at the genus level with S. capitis and S. chromogenes present in all samples. Pig skin revealed populations in the 104 colony-forming units (CFU)/cm2 range with 3% identified as Gram-negative and increased alpha diversity (compared with 102 CFU/cm2 and 10% in humans). While notable taxonomical differences on species levels were seen, pig skin encompassed 97.1% of genera found in human samples. The increased population and variation found support the pig neck as an imperfect but fidelitous subcutaneous injection model that can adequately challenge devices from a microbial standpoint.
Insights
Pig neck skin microbiome analysis reveals higher bacterial populations and diversity compared to humans. Despite differences, pig skin is a suitable injection model for medical devices.
Area of Science:
- Microbiology
- Dermatology
- Biomedical Engineering
Background:
- Pig skin is a common preclinical injection model due to physiological similarities with human skin.
- The microflora of pig neck skin, a frequent injection site, is not well-characterized.
- Understanding skin microflora is crucial for the translatability of preclinical results to human applications.
Purpose of the Study:
- To characterize the microbiome of pig neck skin.
- To compare pig neck skin microflora with human skin microflora at injection sites.
- To evaluate the suitability of pig neck skin as a subcutaneous injection model.
Main Methods:
- Sampling of ten minipigs using tape strips and swabs.
- Analysis via matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S/ITS high-throughput sequencing.
- Confocal laser scanning microscopy and direct comparison with existing human skin microflora data.
Main Results:
- Pig skin microbiome dominated by Firmicutes (94.8%), Proteobacteria (3%), and Actinobacteria (2.2%).
- Staphylococcus spp. (44.4%) were prevalent, with S. capitis and S. chromogenes found in all samples.
- Higher bacterial populations (104 CFU/cm2) and increased alpha diversity were observed in pigs compared to humans (102 CFU/cm2).
Conclusions:
- Pig neck skin exhibits significant microbial differences compared to human skin, particularly in population size and diversity.
- Despite species-level variations, pig skin shares 97.1% of genera with human skin samples.
- The pig neck serves as a viable, albeit imperfect, subcutaneous injection model for microbial challenge testing of medical devices.
