Background: Microbial dysbiosis occurs on cutaneous squamous cell carcinoma (cSCC) in humans, and Staphylococcus aureus is present with increasing relative abundance from normal skin to actinic keratosis to cSCCs. Pathogenic bacteria on the skin can induce inflammation and promote tumorigenesis. cSCC also affects mammalian pets, and there is a need to establish preclinical animal models to test novel therapies. Therefore, the aim of this study was to provide microbiome data for cSCC in cats and dogs.
Methods: We collected nasal planum skin swabs and matched faecal samples from 39 domestic cats and dogs for 16S amplicon sequencing. Thirteen pets had cSCC on (8 on the nasal planum, remainder on leg, mandible, neck, tail, and abdomen) and 26 pets were healthy. The pets with cSCC also had swabs taken adjacent to the lesion, and peri-lesionally.
Results: The microbial profile of the nasal planum in healthy pets was diverse, with an average Shannon index of 3.8, whereas cSCC had a lower average index of 1.5. The pathogenic bacteria S. aureus was abundant on the cSCC lesions and was associated with an overall decrease in commensal species, whereas healthy nasal plana did not exhibit S. aureus colonisation. Peri-lesional swabs typically displayed commensal bacteria, indicating that S. aureus colonisation is site specific to the cSCC. cSCC swabs typically clustered together on ordination plots, whereas healthy swabs were scattered. Additionally, we observed a positive correlation between cSCC stage and S. aureus colonisation.
Conclusion: These findings are consistent with studies of the human cSCC microbiome. Therefore, cats and dogs can serve as an animal model to test new therapies designed to restore microbial dysbiosis. Furthermore, in attempts to decrease S. aureus colonisation and restore eubiosis on cSCC, we have commenced a clinical trial in humans using various topical therapies on actinic keratosis, including topical probiotics.